proc(category27-allgemeinwissen.html) - phpMan

PROC(5)                    Linux Programmer's Manual                   PROC(5)

NAME
       proc - process information pseudo-file system
DESCRIPTION
       The proc file system is a pseudo-file system which is used as an inter-
       face to kernel data structures.  It is commonly mounted at /proc.  Most
       of  it  is  read-only,  but  some  files  allow  kernel variables to be
       changed.
       The following outline gives a quick tour through the /proc hierarchy.
       /proc/[pid]
              There is a numerical subdirectory for each running process;  the
              subdirectory is named by the process ID.  Each such subdirectory
              contains the following pseudo-files and directories.
       /proc/[pid]/auxv (since 2.6.0-test7)
              This contains the contents of the  ELF  interpreter  information
              passed  to the process at exec time.  The format is one unsigned
              long ID plus one unsigned long value for each entry.   The  last
              entry contains two zeros.
       /proc/[pid]/cgroup (since Linux 2.6.24)
              This  file  describes  control  groups to which the process/task
              belongs.  For each cgroup hierarchy there is one entry  contain-
              ing colon-separated fields of the form:
                  5:cpuacct,cpu,cpuset:/daemons
              The colon-separated fields are, from left to right:
                  1. hierarchy ID number
                  2. set of subsystems bound to the hierarchy
                  3. control  group  in  the  hierarchy  to  which the process
                     belongs
              This file is present only if the CONFIG_CGROUPS kernel  configu-
              ration option is enabled.
       /proc/[pid]/cmdline
              This holds the complete command line for the process, unless the
              process is a zombie.  In the latter case, there  is  nothing  in
              this  file:  that  is, a read on this file will return 0 charac-
              ters.  The command-line arguments appear in this file as  a  set
              of  strings  separated by null bytes ('\0'), with a further null
              byte after the last string.
       /proc/[pid]/coredump_filter (since kernel 2.6.23)
              See core(5).
       /proc/[pid]/cpuset (since kernel 2.6.12)
              See cpuset(7).
       /proc/[pid]/cwd
              This is a symbolic link to the current working directory of  the
              process.   To  find out the current working directory of process
              20, for instance, you can do this:
                  $ cd /proc/20/cwd; /bin/pwd
              Note that the pwd command is often a shell built-in,  and  might
              not work properly.  In bash(1), you may use pwd -P.
              In  a  multithreaded process, the contents of this symbolic link
              are not available if the  main  thread  has  already  terminated
              (typically by calling pthread_exit(3)).
       /proc/[pid]/environ
              This file contains the environment for the process.  The entries
              are separated by null bytes ('\0'), and there may be a null byte
              at  the  end.   Thus, to print out the environment of process 1,
              you would do:
                  $ strings /proc/1/environ
       /proc/[pid]/exe
              Under Linux 2.2 and later, this file is a symbolic link contain-
              ing  the actual pathname of the executed command.  This symbolic
              link can be dereferenced normally; attempting to  open  it  will
              open  the  executable.  You can even type /proc/[pid]/exe to run
              another copy of the same executable as is being run  by  process
              [pid].   In  a  multithreaded process, the contents of this sym-
              bolic link are not available if the main thread has already ter-
              minated (typically by calling pthread_exit(3)).
              Under  Linux 2.0 and earlier /proc/[pid]/exe is a pointer to the
              binary which was executed, and appears as a  symbolic  link.   A
              readlink(2)  call  on this file under Linux 2.0 returns a string
              in the format:
                  [device]:inode
              For example, [0301]:1502 would be inode 1502 on device major  03
              (IDE,  MFM,  etc. drives) minor 01 (first partition on the first
              drive).
              find(1) with the -inum option can be used to locate the file.
       /proc/[pid]/fd/
              This is a subdirectory containing one entry for each file  which
              the process has open, named by its file descriptor, and which is
              a symbolic link to the actual file.  Thus, 0 is standard  input,
              1 standard output, 2 standard error, etc.
              For  file descriptors for pipes and sockets, the entries will be
              symbolic links whose content is the file type with the inode.  A
              readlink(2) call on this file returns a string in the format:
                  type:[inode]
              For  example, socket:[2248868] will be a socket and its inode is
              2248868.  For sockets, that inode  can  be  used  to  find  more
              information in one of the files under /proc/net/.
              For  file  descriptors  that  have no corresponding inode (e.g.,
              file descriptors produced by epoll_create(2),  eventfd(2),  ino-
              tify_init(2),  signalfd(2), and timerfd(2)), the entry will be a
              symbolic link with contents of the form
                  anon_inode:<file-type>
              In some cases, the file-type is surrounded by square brackets.
              For example, an epoll file descriptor will have a symbolic  link
              whose content is the string anon_inode:[eventpoll].
              In  a  multithreaded process, the contents of this directory are
              not available if the main thread has already  terminated  (typi-
              cally by calling pthread_exit(3)).
              Programs  that  will take a filename as a command-line argument,
              but will not take input from standard input if  no  argument  is
              supplied,  or that write to a file named as a command-line argu-
              ment, but will not send their output to standard  output  if  no
              argument  is  supplied, can nevertheless be made to use standard
              input or standard out using /proc/[pid]/fd.  For example, assum-
              ing  that -i is the flag designating an input file and -o is the
              flag designating an output file:
                  $ foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...
              and you have a working filter.
              /proc/self/fd/N is approximately the same as /dev/fd/N  in  some
              UNIX and UNIX-like systems.  Most Linux MAKEDEV scripts symboli-
              cally link /dev/fd to /proc/self/fd, in fact.
              Most systems provide symbolic links /dev/stdin, /dev/stdout, and
              /dev/stderr, which respectively link to the files 0, 1, and 2 in
              /proc/self/fd.  Thus the example command above could be  written
              as:
                  $ foobar -i /dev/stdin -o /dev/stdout ...
       /proc/[pid]/fdinfo/ (since kernel 2.6.22)
              This  is a subdirectory containing one entry for each file which
              the process has open, named by its file  descriptor.   The  con-
              tents  of  each file can be read to obtain information about the
              corresponding file descriptor, for example:
                  $ cat /proc/12015/fdinfo/4
                  pos:    1000
                  flags:  01002002
              The pos field is a decimal number showing the current file  off-
              set.   The flags field is an octal number that displays the file
              access mode and file status flags (see open(2)).
              The files in this directory are readable only by  the  owner  of
              the process.
       /proc/[pid]/io (since kernel 2.6.20)
              This file contains I/O statistics for the process, for example:
                  # cat /proc/3828/io
                  rchar: 323934931
                  wchar: 323929600
                  syscr: 632687
                  syscw: 632675
                  read_bytes: 0
                  write_bytes: 323932160
                  cancelled_write_bytes: 0
              The fields are as follows:
              rchar: characters read
                     The number of bytes which this task has caused to be read
                     from storage.  This is simply the sum of bytes which this
                     process  passed  to read(2) and similar system calls.  It
                     includes things such as terminal I/O and is unaffected by
                     whether or not actual physical disk I/O was required (the
                     read might have been satisfied from pagecache).
              wchar: characters written
                     The number of bytes which this task has caused, or  shall
                     cause  to be written to disk.  Similar caveats apply here
                     as with rchar.
              syscr: read syscalls
                     Attempt to count the number of read I/O  operations--that
                     is, system calls such as read(2) and pread(2).
              syscw: write syscalls
                     Attempt to count the number of write I/O operations--that
                     is, system calls such as write(2) and pwrite(2).
              read_bytes: bytes read
                     Attempt to count the number of bytes which  this  process
                     really  did  cause  to be fetched from the storage layer.
                     This is accurate for block-backed filesystems.
              write_bytes: bytes written
                     Attempt to count the number of bytes which  this  process
                     caused to be sent to the storage layer.
              cancelled_write_bytes:
                     The big inaccuracy here is truncate.  If a process writes
                     1MB to a file and then deletes the file, it will in  fact
                     perform  no writeout.  But it will have been accounted as
                     having caused 1MB of write.  In other words:  this  field
                     represents  the number of bytes which this process caused
                     to not happen, by truncating pagecache.  A task can cause
                     "negative"  I/O  too.   If this task truncates some dirty
                     pagecache, some I/O which another task has been accounted
                     for (in its write_bytes) will not be happening.
              Note:  In  the  current implementation, things are a bit racy on
              32-bit systems: if process A reads  process  B's  /proc/[pid]/io
              while  process  B  is  updating  one  of  these 64-bit counters,
              process A could see an intermediate result.
       /proc/[pid]/limits (since kernel 2.6.24)
              This file displays the soft limit, hard limit, and units of mea-
              surement  for  each  of the process's resource limits (see getr-
              limit(2)).  Up to and including Linux 2.6.35, this file is  pro-
              tected  to  allow  reading  only by the real UID of the process.
              Since Linux 2.6.36, this file is readable by all  users  on  the
              system.
       /proc/[pid]/map_files/ (since kernel 3.3)
              This  subdirectory  contains  entries  corresponding  to memory-
              mapped files (see mmap(2)).  Entries are named by memory  region
              start  and  end address pair (expressed as hexadecimal numbers),
              and are symbolic links to the mapped files themselves.  Here  is
              an example, with the output wrapped and reformatted to fit on an
              80-column display:
                  $ ls -l /proc/self/map_files/
                  lr--------. 1 root root 64 Apr 16 21:31
                              3252e00000-3252e20000 -> /usr/lib64/ld-2.15.so
                  ...
              Although these entries are present for memory regions that  were
              mapped  with  the MAP_FILE flag, the way anonymous shared memory
              (regions created with the MAP_ANON | MAP_SHARED flags) is imple-
              mented  in  Linux  means  that  such regions also appear on this
              directory.  Here is an example where  the  target  file  is  the
              deleted /dev/zero one:

                  lrw-------. 1 root root 64 Apr 16 21:33
                              7fc075d2f000-7fc075e6f000 -> /dev/zero (deleted)
              This  directory  appears  only  if the CONFIG_CHECKPOINT_RESTORE
              kernel configuration option is enabled.
       /proc/[pid]/maps
              A file containing the currently mapped memory regions and  their
              access  permissions.   See  mmap(2) for some further information
              about memory mappings.
              The format of the file is:
       address           perms offset  dev   inode       pathname
       00400000-00452000 r-xp 00000000 08:02 173521      /usr/bin/dbus-daemon
       00651000-00652000 r--p 00051000 08:02 173521      /usr/bin/dbus-daemon
       00652000-00655000 rw-p 00052000 08:02 173521      /usr/bin/dbus-daemon
       00e03000-00e24000 rw-p 00000000 00:00 0           [heap]
       00e24000-011f7000 rw-p 00000000 00:00 0           [heap]
       ...
       35b1800000-35b1820000 r-xp 00000000 08:02 135522  /usr/lib64/ld-2.15.so
       35b1a1f000-35b1a20000 r--p 0001f000 08:02 135522  /usr/lib64/ld-2.15.so
       35b1a20000-35b1a21000 rw-p 00020000 08:02 135522  /usr/lib64/ld-2.15.so
       35b1a21000-35b1a22000 rw-p 00000000 00:00 0
       35b1c00000-35b1dac000 r-xp 00000000 08:02 135870  /usr/lib64/libc-2.15.so
       35b1dac000-35b1fac000 ---p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so
       35b1fac000-35b1fb0000 r--p 001ac000 08:02 135870  /usr/lib64/libc-2.15.so
       35b1fb0000-35b1fb2000 rw-p 001b0000 08:02 135870  /usr/lib64/libc-2.15.so
       ...
       f2c6ff8c000-7f2c7078c000 rw-p 00000000 00:00 0    [stack:986]
       ...
       7fffb2c0d000-7fffb2c2e000 rw-p 00000000 00:00 0   [stack]
       7fffb2d48000-7fffb2d49000 r-xp 00000000 00:00 0   [vdso]
              The address field is the address space in the process  that  the
              mapping occupies.  The perms field is a set of permissions:
                   r = read
                   w = write
                   x = execute
                   s = shared
                   p = private (copy on write)
              The  offset  field  is the offset into the file/whatever; dev is
              the device (major:minor); inode is the inode on that device.   0
              indicates that no inode is associated with the memory region, as
              would be the case with BSS (uninitialized data).
              The pathname field will usually be the file that is backing  the
              mapping.  For ELF files, you can easily coordinate with the off-
              set field by looking at the Offset  field  in  the  ELF  program
              headers (readelf -l).
              There are additional helpful pseudo-paths:
                   [stack]
                          The  initial  process's  (also  known  as  the  main
                          thread's) stack.
                   [stack:<tid>] (since Linux 3.4)
                          A thread's stack (where the <tid> is a  thread  ID).
                          It corresponds to the /proc/[pid]/task/[tid]/ path.
                   [vdso] The virtual dynamically linked shared object.
                   [heap] The process's heap.
              If  the pathname field is blank, this is an anonymous mapping as
              obtained via the mmap(2) function.  There  is  no  easy  way  to
              coordinate  this back to a process's source, short of running it
              through gdb(1), strace(1), or similar.
              Under Linux 2.0 there is no field giving pathname.
       /proc/[pid]/mem
              This file can be used to access the pages of a process's  memory
              through open(2), read(2), and lseek(2).
       /proc/[pid]/mountinfo (since Linux 2.6.26)
              This  file contains information about mount points.  It contains
              lines of the form:
              36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
              (1)(2)(3)   (4)   (5)      (6)      (7)   (8) (9)   (10)         (11)
              The numbers in  parentheses  are  labels  for  the  descriptions
              below:
              (1)  mount  ID:  unique  identifier  of the mount (may be reused
                   after umount(2)).
              (2)  parent ID: ID of parent mount (or of self for  the  top  of
                   the mount tree).
              (3)  major:minor:  value of st_dev for files on file system (see
                   stat(2)).
              (4)  root: root of the mount within the file system.
              (5)  mount point: mount point relative to the process's root.
              (6)  mount options: per-mount options.
              (7)  optional  fields:  zero  or  more  fields   of   the   form
                   "tag[:value]".
              (8)  separator: marks the end of the optional fields.
              (9)  file   system  type:  name  of  file  system  in  the  form
                   "type[.subtype]".
              (10) mount source: file system-specific information or "none".
              (11) super options: per-super block options.
              Parsers should ignore all unrecognized  optional  fields.   Cur-
              rently the possible optional fields are:
                   shared:X          mount is shared in peer group X
                   master:X          mount is slave to peer group X
                   propagate_from:X  mount  is  slave and receives propagation
                                     from peer group X (*)
                   unbindable        mount is unbindable
              (*) X is the closest dominant peer  group  under  the  process's
              root.  If X is the immediate master of the mount, or if there is
              no dominant peer group under the same root, then only the  "mas-
              ter:X" field is present and not the "propagate_from:X" field.
              For  more  information  on  mount  propagation  see:  Documenta-
              tion/filesystems/sharedsubtree.txt in the  Linux  kernel  source
              tree.
       /proc/[pid]/mounts (since Linux 2.4.19)
              This  is a list of all the file systems currently mounted in the
              process's mount namespace.  The format of  this  file  is  docu-
              mented  in  fstab(5).  Since kernel version 2.6.15, this file is
              pollable: after opening the file for reading, a change  in  this
              file  (i.e., a file system mount or unmount) causes select(2) to
              mark  the  file  descriptor  as  readable,   and   poll(2)   and
              epoll_wait(2) mark the file as having an error condition.
       /proc/[pid]/mountstats (since Linux 2.6.17)
              This  file exports information (statistics, configuration infor-
              mation) about the mount points  in  the  process's  name  space.
              Lines in this file have the form:
              device /dev/sda7 mounted on /home with fstype ext3 [statistics]
              (       1      )            ( 2 )             (3 ) (4)
              The fields in each line are:
              (1)  The  name  of the mounted device (or "nodevice" if there is
                   no corresponding device).
              (2)  The mount point within the file system tree.
              (3)  The file system type.
              (4)  Optional statistics and  configuration  information.   Cur-
                   rently  (as  at Linux 2.6.26), only NFS file systems export
                   information via this field.
              This file is readable only by the owner of the process.
       /proc/[pid]/ns/ (since Linux 3.0)
              This is a subdirectory containing one entry for  each  namespace
              that  supports  being  manipulated by setns(2).  For information
              about namespaces, see clone(2).
       /proc/[pid]/ns/ipc (since Linux 3.0)
              Bind mounting this file (see mount(2)) to somewhere else in  the
              filesystem  keeps  the IPC namespace of the process specified by
              pid alive even if all processes currently in the namespace  ter-
              minate.
              Opening this file returns a file handle for the IPC namespace of
              the process specified by pid.  As long as this  file  descriptor
              remains  open,  the IPC namespace will remain alive, even if all
              processes in the namespace terminate.  The file  descriptor  can
              be passed to setns(2).
       /proc/[pid]/ns/net (since Linux 3.0)
              Bind  mounting this file (see mount(2)) to somewhere else in the
              filesystem keeps the network namespace of the process  specified
              by pid alive even if all processes in the namespace terminate.
              Opening  this  file returns a file handle for the network names-
              pace of the process specified by pid.   As  long  as  this  file
              descriptor  remains  open,  the  network  namespace  will remain
              alive, even if all processes in the  namespace  terminate.   The
              file descriptor can be passed to setns(2).
       /proc/[pid]/ns/uts (since Linux 3.0)
              Bind  mounting this file (see mount(2)) to somewhere else in the
              filesystem keeps the UTS namespace of the process  specified  by
              pid  alive even if all processes currently in the namespace ter-
              minate.
              Opening this file returns a file handle for the UTS namespace of
              the  process  specified by pid.  As long as this file descriptor
              remains open, the UTS namespace will remain alive, even  if  all
              processes  in  the namespace terminate.  The file descriptor can
              be passed to setns(2).
       /proc/[pid]/numa_maps (since Linux 2.6.14)
              See numa(7).
       /proc/[pid]/oom_adj (since Linux 2.6.11)
              This file can be used to adjust the score used to  select  which
              process  should  be  killed in an out-of-memory (OOM) situation.
              The kernel uses this value for  a  bit-shift  operation  of  the
              process's  oom_score value: valid values are in the range -16 to
              +15, plus the special  value  -17,  which  disables  OOM-killing
              altogether  for  this  process.   A positive score increases the
              likelihood of this process being killed  by  the  OOM-killer;  a
              negative score decreases the likelihood.
              The default value for this file is 0; a new process inherits its
              parent's  oom_adj  setting.   A  process  must   be   privileged
              (CAP_SYS_RESOURCE) to update this file.
              Since  Linux  2.6.36, use of this file is deprecated in favor of
              /proc/[pid]/oom_score_adj.
       /proc/[pid]/oom_score (since Linux 2.6.11)
              This file displays the current score that the  kernel  gives  to
              this process for the purpose of selecting a process for the OOM-
              killer.  A higher score means that the process is more likely to
              be  selected by the OOM-killer.  The basis for this score is the
              amount of memory used by the  process,  with  increases  (+)  or
              decreases (-) for factors including:
              * whether  the  process  creates a lot of children using fork(2)
                (+);
              * whether the process has been running a long time, or has  used
                a lot of CPU time (-);
              * whether the process has a low nice value (i.e., > 0) (+);
              * whether the process is privileged (-); and
              * whether the process is making direct hardware access (-).
              The  oom_score  also  reflects  the  adjustment specified by the
              oom_score_adj or oom_adj setting for the process.
       /proc/[pid]/oom_score_adj (since Linux 2.6.36)
              This file can be used to adjust the badness  heuristic  used  to
              select which process gets killed in out-of-memory conditions.
              The  badness  heuristic  assigns  a value to each candidate task
              ranging from 0 (never kill) to 1000 (always kill)  to  determine
              which  process  is targeted.  The units are roughly a proportion
              along that range of allowed  memory  the  process  may  allocate
              from, based on an estimation of its current memory and swap use.
              For example, if a task is using all allowed memory, its  badness
              score  will be 1000.  If it is using half of its allowed memory,
              its score will be 500.
              There is an additional factor included  in  the  badness  score:
              root processes are given 3% extra memory over other tasks.
              The  amount  of "allowed" memory depends on the context in which
              the OOM-killer was called.  If it is due to the memory  assigned
              to  the  allocating  task's  cpuset being exhausted, the allowed
              memory represents the set of mems assigned to that  cpuset  (see
              cpuset(7)).   If  it  is  due  to  a  mempolicy's  node(s) being
              exhausted, the allowed memory represents the  set  of  mempolicy
              nodes.   If  it  is  due to a memory limit (or swap limit) being
              reached, the allowed memory is that configured limit.   Finally,
              if  it  is  due  to  the  entire system being out of memory, the
              allowed memory represents all allocatable resources.
              The value of oom_score_adj is added to the badness score  before
              it  is  used to determine which task to kill.  Acceptable values
              range    from     -1000     (OOM_SCORE_ADJ_MIN)     to     +1000
              (OOM_SCORE_ADJ_MAX).   This  allows  user  space  to control the
              preference for OOM-killing, ranging  from  always  preferring  a
              certain  task  or completely disabling it from OOM-killing.  The
              lowest possible value, -1000, is equivalent  to  disabling  OOM-
              killing  entirely  for  that task, since it will always report a
              badness score of 0.
              Consequently, it is very simple for user  space  to  define  the
              amount   of  memory  to  consider  for  each  task.   Setting  a
              oom_score_adj value of +500, for example, is roughly  equivalent
              to  allowing  the  remainder  of  tasks sharing the same system,
              cpuset, mempolicy, or memory  controller  resources  to  use  at
              least  50%  more  memory.   A  value of -500, on the other hand,
              would be roughly equivalent to discounting  50%  of  the  task's
              allowed  memory  from  being  considered  as scoring against the
              task.
              For    backward    compatibility    with    previous    kernels,
              /proc/[pid]/oom_adj can still be used to tune the badness score.
              Its value is scaled linearly with oom_score_adj.
              Writing to /proc/[pid]/oom_score_adj or /proc/[pid]/oom_adj will
              change the other with its scaled value.
       /proc/[pid]/root
              UNIX  and  Linux  support  the idea of a per-process root of the
              file system, set by the chroot(2) system call.  This file  is  a
              symbolic  link  that points to the process's root directory, and
              behaves as exe, fd/*, etc. do.
              In a multithreaded process, the contents of this  symbolic  link
              are  not  available  if  the  main thread has already terminated
              (typically by calling pthread_exit(3)).
       /proc/[pid]/smaps (since Linux 2.6.14)
              This file shows memory consumption for  each  of  the  process's
              mappings.   For each of mappings there is a series of lines such
              as the following:
                  08048000-080bc000 r-xp 00000000 03:02 13130      /bin/bash
                  Size:               464 kB
                  Rss:                424 kB
                  Shared_Clean:       424 kB
                  Shared_Dirty:         0 kB
                  Private_Clean:        0 kB
                  Private_Dirty:        0 kB
              The first of these lines shows the same information as  is  dis-
              played for the mapping in /proc/[pid]/maps.  The remaining lines
              show the size of the mapping, the amount of the mapping that  is
              currently  resident in RAM, the number of clean and dirty shared
              pages in the mapping, and the number of clean and dirty  private
              pages in the mapping.
              This file is present only if the CONFIG_MMU kernel configuration
              option is enabled.
       /proc/[pid]/stat
              Status information about the process.  This is  used  by  ps(1).
              It is defined in /usr/src/linux/fs/proc/array.c.
              The  fields,  in order, with their proper scanf(3) format speci-
              fiers, are:
              pid %d      (1) The process ID.
              comm %s     (2) The filename of the executable, in  parentheses.
                          This  is  visible  whether  or not the executable is
                          swapped out.
              state %c    (3) One character from the string "RSDZTW"  where  R
                          is  running, S is sleeping in an interruptible wait,
                          D is waiting in uninterruptible  disk  sleep,  Z  is
                          zombie,  T is traced or stopped (on a signal), and W
                          is paging.
              ppid %d     (4) The PID of the parent.
              pgrp %d     (5) The process group ID of the process.
              session %d  (6) The session ID of the process.
              tty_nr %d   (7) The controlling terminal of the  process.   (The
                          minor  device number is contained in the combination
                          of bits 31 to 20 and 7 to 0; the major device number
                          is in bits 15 to 8.)
              tpgid %d    (8)  The  ID  of the foreground process group of the
                          controlling terminal of the process.
              flags %u (%lu before Linux 2.6.22)
                          (9) The kernel flags word of the process.   For  bit
                          meanings,  see  the PF_* defines in the Linux kernel
                          source file include/linux/sched.h.   Details  depend
                          on the kernel version.
              minflt %lu  (10) The number of minor faults the process has made
                          which have not required loading a memory  page  from
                          disk.
              cminflt %lu (11)  The  number of minor faults that the process's
                          waited-for children have made.
              majflt %lu  (12) The number of major faults the process has made
                          which have required loading a memory page from disk.
              cmajflt %lu (13)  The  number of major faults that the process's
                          waited-for children have made.
              utime %lu   (14) Amount of  time  that  this  process  has  been
                          scheduled  in  user  mode,  measured  in clock ticks
                          (divide  by  sysconf(_SC_CLK_TCK)).   This  includes
                          guest time, guest_time (time spent running a virtual
                          CPU, see below), so that applications that  are  not
                          aware  of the guest time field do not lose that time
                          from their calculations.
              stime %lu   (15) Amount of  time  that  this  process  has  been
                          scheduled  in  kernel  mode, measured in clock ticks
                          (divide by sysconf(_SC_CLK_TCK)).
              cutime %ld  (16) Amount of time that this  process's  waited-for
                          children  have been scheduled in user mode, measured
                          in clock  ticks  (divide  by  sysconf(_SC_CLK_TCK)).
                          (See  also  times(2).)   This  includes  guest time,
                          cguest_time (time spent running a virtual  CPU,  see
                          below).
              cstime %ld  (17)  Amount  of time that this process's waited-for
                          children have been scheduled in  kernel  mode,  mea-
                          sured      in     clock     ticks     (divide     by
                          sysconf(_SC_CLK_TCK)).
              priority %ld
                          (18) (Explanation for Linux 2.6) For processes  run-
                          ning  a  real-time  scheduling policy (policy below;
                          see  sched_setscheduler(2)),  this  is  the  negated
                          scheduling priority, minus one; that is, a number in
                          the range -2 to  -100,  corresponding  to  real-time
                          priorities  1  to 99.  For processes running under a
                          non-real-time scheduling policy,  this  is  the  raw
                          nice  value  (setpriority(2))  as represented in the
                          kernel.  The kernel stores nice values as numbers in
                          the range 0 (high) to 39 (low), corresponding to the
                          user-visible nice range of -20 to 19.
                          Before Linux 2.6, this was a scaled value  based  on
                          the scheduler weighting given to this process.
              nice %ld    (19) The nice value (see setpriority(2)), a value in
                          the range 19 (low priority) to -20 (high priority).
              num_threads %ld
                          (20) Number of threads in this process (since  Linux
                          2.6).   Before kernel 2.6, this field was hard coded
                          to 0 as a placeholder for an earlier removed field.
              itrealvalue %ld
                          (21) The time in jiffies before the next SIGALRM  is
                          sent to the process due to an interval timer.  Since
                          kernel 2.6.17, this field is no  longer  maintained,
                          and is hard coded as 0.
              starttime %llu (was %lu before Linux 2.6)
                          (22) The time the process started after system boot.
                          In  kernels  before  Linux  2.6,  this   value   was
                          expressed in jiffies.  Since Linux 2.6, the value is
                          expressed    in    clock    ticks     (divide     by
                          sysconf(_SC_CLK_TCK)).
              vsize %lu   (23) Virtual memory size in bytes.
              rss %ld     (24)  Resident Set Size: number of pages the process
                          has in real memory.  This is just  the  pages  which
                          count  toward text, data, or stack space.  This does
                          not include pages which have not been  demand-loaded
                          in, or which are swapped out.
              rsslim %lu  (25)  Current  soft limit in bytes on the rss of the
                          process; see the description of RLIMIT_RSS in  getr-
                          limit(2).
              startcode %lu
                          (26) The address above which program text can run.
              endcode %lu (27) The address below which program text can run.
              startstack %lu
                          (28)  The address of the start (i.e., bottom) of the
                          stack.
              kstkesp %lu (29) The current value of ESP  (stack  pointer),  as
                          found in the kernel stack page for the process.
              kstkeip %lu (30) The current EIP (instruction pointer).
              signal %lu  (31)  The  bitmap of pending signals, displayed as a
                          decimal number.  Obsolete, because it does not  pro-
                          vide   information   on   real-time   signals;   use
                          /proc/[pid]/status instead.
              blocked %lu (32) The bitmap of blocked signals, displayed  as  a
                          decimal  number.  Obsolete, because it does not pro-
                          vide   information   on   real-time   signals;   use
                          /proc/[pid]/status instead.
              sigignore %lu
                          (33)  The  bitmap of ignored signals, displayed as a
                          decimal number.  Obsolete, because it does not  pro-
                          vide   information   on   real-time   signals;   use
                          /proc/[pid]/status instead.
              sigcatch %lu
                          (34) The bitmap of caught signals,  displayed  as  a
                          decimal  number.  Obsolete, because it does not pro-
                          vide   information   on   real-time   signals;   use
                          /proc/[pid]/status instead.
              wchan %lu   (35)  This  is the "channel" in which the process is
                          waiting.  It is the address of a  system  call,  and
                          can be looked up in a namelist if you need a textual
                          name.  (If you have an  up-to-date  /etc/psdatabase,
                          then try ps -l to see the WCHAN field in action.)
              nswap %lu   (36) Number of pages swapped (not maintained).
              cnswap %lu  (37) Cumulative nswap for child processes (not main-
                          tained).
              exit_signal %d (since Linux 2.1.22)
                          (38) Signal to be sent to parent when we die.
              processor %d (since Linux 2.2.8)
                          (39) CPU number last executed on.
              rt_priority %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
                          (40) Real-time scheduling priority, a number in  the
                          range  1 to 99 for processes scheduled under a real-
                          time policy, or 0, for non-real-time processes  (see
                          sched_setscheduler(2)).
              policy %u (since Linux 2.5.19; was %lu before Linux 2.6.22)
                          (41)  Scheduling policy (see sched_setscheduler(2)).
                          Decode using the SCHED_* constants in linux/sched.h.
              delayacct_blkio_ticks %llu (since Linux 2.6.18)
                          (42) Aggregated block I/O delays, measured in  clock
                          ticks (centiseconds).
              guest_time %lu (since Linux 2.6.24)
                          (43) Guest time of the process (time spent running a
                          virtual CPU for a guest operating system),  measured
                          in clock ticks (divide by sysconf(_SC_CLK_TCK)).
              cguest_time %ld (since Linux 2.6.24)
                          (44)  Guest time of the process's children, measured
                          in clock ticks (divide by sysconf(_SC_CLK_TCK)).
       /proc/[pid]/statm
              Provides information about memory usage, measured in pages.  The
              columns are:
                  size       (1) total program size
                             (same as VmSize in /proc/[pid]/status)
                  resident   (2) resident set size
                             (same as VmRSS in /proc/[pid]/status)
                  share      (3) shared pages (i.e., backed by a file)
                  text       (4) text (code)
                  lib        (5) library (unused in Linux 2.6)
                  data       (6) data + stack
                  dt         (7) dirty pages (unused in Linux 2.6)
       /proc/[pid]/status
              Provides   much  of  the  information  in  /proc/[pid]/stat  and
              /proc/[pid]/statm in a format that's easier for humans to parse.
              Here's an example:
                  $ cat /proc/$$/status
                  Name:   bash
                  State:  S (sleeping)
                  Tgid:   3515
                  Pid:    3515
                  PPid:   3452
                  TracerPid:      0
                  Uid:    1000    1000    1000    1000
                  Gid:    100     100     100     100
                  FDSize: 256
                  Groups: 16 33 100
                  VmPeak:     9136 kB
                  VmSize:     7896 kB
                  VmLck:         0 kB
                  VmHWM:      7572 kB
                  VmRSS:      6316 kB
                  VmData:     5224 kB
                  VmStk:        88 kB
                  VmExe:       572 kB
                  VmLib:      1708 kB
                  VmPTE:        20 kB
                  Threads:        1
                  SigQ:   0/3067
                  SigPnd: 0000000000000000
                  ShdPnd: 0000000000000000
                  SigBlk: 0000000000010000
                  SigIgn: 0000000000384004
                  SigCgt: 000000004b813efb
                  CapInh: 0000000000000000
                  CapPrm: 0000000000000000
                  CapEff: 0000000000000000
                  CapBnd: ffffffffffffffff
                  Cpus_allowed:   00000001
                  Cpus_allowed_list:      0
                  Mems_allowed:   1
                  Mems_allowed_list:      0
                  voluntary_ctxt_switches:        150
                  nonvoluntary_ctxt_switches:     545
              The fields are as follows:
              * Name: Command run by this process.
              * State: Current state of the process.  One of "R (running)", "S
                (sleeping)", "D (disk  sleep)",  "T  (stopped)",  "T  (tracing
                stop)", "Z (zombie)", or "X (dead)".
              * Tgid: Thread group ID (i.e., Process ID).
              * Pid: Thread ID (see gettid(2)).
              * PPid: PID of parent process.
              * TracerPid: PID of process tracing this process (0 if not being
                traced).
              * Uid, Gid: Real, effective, saved set,  and  file  system  UIDs
                (GIDs).
              * FDSize: Number of file descriptor slots currently allocated.
              * Groups: Supplementary group list.
              * VmPeak: Peak virtual memory size.
              * VmSize: Virtual memory size.
              * VmLck: Locked memory size (see mlock(3)).
              * VmHWM: Peak resident set size ("high water mark").
              * VmRSS: Resident set size.
              * VmData, VmStk, VmExe: Size of data, stack, and text segments.
              * VmLib: Shared library code size.
              * VmPTE: Page table entries size (since Linux 2.6.10).
              * Threads: Number of threads in process containing this thread.
              * SigQ:  This  field  contains  two slash-separated numbers that
                relate to queued signals for the real user ID of this process.
                The  first  of these is the number of currently queued signals
                for this real user ID, and the second is the resource limit on
                the  number  of  queued  signals  for  this  process  (see the
                description of RLIMIT_SIGPENDING in getrlimit(2)).
              * SigPnd, ShdPnd: Number of signals pending for thread  and  for
                process as a whole (see pthreads(7) and signal(7)).
              * SigBlk,   SigIgn,   SigCgt:  Masks  indicating  signals  being
                blocked, ignored, and caught (see signal(7)).
              * CapInh, CapPrm,  CapEff:  Masks  of  capabilities  enabled  in
                inheritable,  permitted,  and  effective  sets  (see capabili-
                ties(7)).
              * CapBnd: Capability Bounding  set  (since  kernel  2.6.26,  see
                capabilities(7)).
              * Cpus_allowed:  Mask  of  CPUs  on  which  this process may run
                (since Linux 2.6.24, see cpuset(7)).
              * Cpus_allowed_list: Same as  previous,  but  in  "list  format"
                (since Linux 2.6.26, see cpuset(7)).
              * Mems_allowed:  Mask  of  memory  nodes allowed to this process
                (since Linux 2.6.24, see cpuset(7)).
              * Mems_allowed_list: Same as  previous,  but  in  "list  format"
                (since Linux 2.6.26, see cpuset(7)).
              * voluntary_context_switches,     nonvoluntary_context_switches:
                Number of voluntary and involuntary  context  switches  (since
                Linux 2.6.23).
       /proc/[pid]/task (since Linux 2.6.0-test6)
              This  is  a  directory  that  contains one subdirectory for each
              thread in the process.  The name of  each  subdirectory  is  the
              numerical  thread  ID  ([tid])  of  the  thread (see gettid(2)).
              Within each of these subdirectories, there is  a  set  of  files
              with the same names and contents as under the /proc/[pid] direc-
              tories.  For attributes that are shared by all threads, the con-
              tents  for each of the files under the task/[tid] subdirectories
              will be the same as in the  corresponding  file  in  the  parent
              /proc/[pid]  directory (e.g., in a multithreaded process, all of
              the task/[tid]/cwd  files  will  have  the  same  value  as  the
              /proc/[pid]/cwd  file  in the parent directory, since all of the
              threads in a process share a working directory).  For attributes
              that are distinct for each thread, the corresponding files under
              task/[tid] may have different values (e.g.,  various  fields  in
              each  of  the  task/[tid]/status files may be different for each
              thread).
              In a multithreaded process, the contents of the /proc/[pid]/task
              directory  are not available if the main thread has already ter-
              minated (typically by calling pthread_exit(3)).
       /proc/apm
              Advanced power management version and battery  information  when
              CONFIG_APM is defined at kernel compilation time.
       /proc/bus
              Contains subdirectories for installed busses.
       /proc/bus/pccard
              Subdirectory  for  PCMCIA  devices  when CONFIG_PCMCIA is set at
              kernel compilation time.
       /proc/bus/pccard/drivers
       /proc/bus/pci
              Contains various bus subdirectories and pseudo-files  containing
              information  about  PCI  busses,  installed  devices, and device
              drivers.  Some of these files are not ASCII.
       /proc/bus/pci/devices
              Information about PCI devices.  They  may  be  accessed  through
              lspci(8) and setpci(8).
       /proc/cmdline
              Arguments  passed  to the Linux kernel at boot time.  Often done
              via a boot manager such as lilo(8) or grub(8).
       /proc/config.gz (since Linux 2.6)
              This file exposes the configuration options that  were  used  to
              build  the  currently running kernel, in the same format as they
              would be shown in the .config file that resulted when  configur-
              ing  the  kernel  (using make xconfig, make config, or similar).
              The file contents are compressed;  view  or  search  them  using
              zcat(1), zgrep(1), etc.  As long as no changes have been made to
              the following file, the contents of /proc/config.gz are the same
              as those provided by :
                  cat /lib/modules/$(uname -r)/build/.config
              /proc/config.gz  is  provided  only  if the kernel is configured
              with CONFIG_IKCONFIG_PROC.
       /proc/cpuinfo
              This is a collection of CPU and  system  architecture  dependent
              items,  for  each  supported architecture a different list.  Two
              common  entries  are  processor  which  gives  CPU  number   and
              bogomips;  a  system  constant  that is calculated during kernel
              initialization.  SMP machines have  information  for  each  CPU.
              The lscpu(1) command gathers its information from this file.
       /proc/devices
              Text  listing  of  major numbers and device groups.  This can be
              used by MAKEDEV scripts for consistency with the kernel.
       /proc/diskstats (since Linux 2.5.69)
              This file contains disk I/O statistics  for  each  disk  device.
              See  the  Linux kernel source file Documentation/iostats.txt for
              further information.
       /proc/dma
              This is a list of the registered ISA DMA (direct memory  access)
              channels in use.
       /proc/driver
              Empty subdirectory.
       /proc/execdomains
              List of the execution domains (ABI personalities).
       /proc/fb
              Frame buffer information when CONFIG_FB is defined during kernel
              compilation.
       /proc/filesystems
              A text listing of the file systems which are  supported  by  the
              kernel,  namely file systems which were compiled into the kernel
              or  whose  kernel  modules  are  currently  loaded.   (See  also
              filesystems(5).)   If a file system is marked with "nodev", this
              means that it does not require a  block  device  to  be  mounted
              (e.g., virtual file system, network file system).
              Incidentally,  this  file  may  be used by mount(8) when no file
              system is specified and it didn't manage to determine  the  file
              system type.  Then file systems contained in this file are tried
              (excepted those that are marked with "nodev").
       /proc/fs
              Empty subdirectory.
       /proc/ide
              This directory exists on systems with the IDE  bus.   There  are
              directories  for  each  IDE  channel and attached device.  Files
              include:
                  cache              buffer size in KB
                  capacity           number of sectors
                  driver             driver version
                  geometry           physical and logical geometry
                  identify           in hexadecimal
                  media              media type
                  model              manufacturer's model number
                  settings           drive settings
                  smart_thresholds   in hexadecimal
                  smart_values       in hexadecimal
              The hdparm(8) utility provides access to this information  in  a
              friendly format.
       /proc/interrupts
              This  is  used to record the number of interrupts per CPU per IO
              device.  Since Linux 2.6.24, for the i386 and  x86_64  architec-
              tures,  at  least, this also includes interrupts internal to the
              system (that is, not associated with a device as such), such  as
              NMI  (nonmaskable  interrupt),  LOC (local timer interrupt), and
              for SMP systems, TLB (TLB flush  interrupt),  RES  (rescheduling
              interrupt),  CAL  (remote function call interrupt), and possibly
              others.  Very easy to read formatting, done in ASCII.
       /proc/iomem
              I/O memory map in Linux 2.4.
       /proc/ioports
              This is a list of currently registered Input-Output port regions
              that are in use.
       /proc/kallsyms (since Linux 2.5.71)
              This  holds  the  kernel exported symbol definitions used by the
              modules(X) tools to dynamically link and bind loadable  modules.
              In  Linux  2.5.47 and earlier, a similar file with slightly dif-
              ferent syntax was named ksyms.
       /proc/kcore
              This file represents the physical memory of the  system  and  is
              stored  in the ELF core file format.  With this pseudo-file, and
              an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB can be
              used to examine the current state of any kernel data structures.
              The  total  length  of  the  file is the size of physical memory
              (RAM) plus 4KB.
       /proc/kmsg
              This file can be used instead of the syslog(2)  system  call  to
              read  kernel messages.  A process must have superuser privileges
              to read this file, and only one process should read  this  file.
              This  file  should  not  be  read if a syslog process is running
              which uses the syslog(2) system call facility to log kernel mes-
              sages.
              Information in this file is retrieved with the dmesg(1) program.
       /proc/ksyms (Linux 1.1.23-2.5.47)
              See /proc/kallsyms.
       /proc/loadavg
              The  first  three  fields  in this file are load average figures
              giving the number of jobs in the run queue (state R) or  waiting
              for disk I/O (state D) averaged over 1, 5, and 15 minutes.  They
              are the same as the load average numbers given by uptime(1)  and
              other  programs.  The fourth field consists of two numbers sepa-
              rated by a slash (/).  The first of these is the number of  cur-
              rently runnable kernel scheduling entities (processes, threads).
              The value after the slash is the  number  of  kernel  scheduling
              entities that currently exist on the system.  The fifth field is
              the PID of the process that was most  recently  created  on  the
              system.
       /proc/locks
              This  file  shows current file locks (flock(2) and fcntl(2)) and
              leases (fcntl(2)).
       /proc/malloc (only up to and including Linux 2.2)
              This file is present only  if  CONFIG_DEBUG_MALLOC  was  defined
              during compilation.
       /proc/meminfo
              This  file  reports statistics about memory usage on the system.
              It is used by free(1) to report the amount of free and used mem-
              ory (both physical and swap) on the system as well as the shared
              memory and buffers used by the kernel.  Each line  of  the  file
              consists  of a parameter name, followed by a colon, the value of
              the parameter, and an option unit of measurement  (e.g.,  "kB").
              The  list  below  describes  the  parameter names and the format
              specifier required to read the field  value.   Except  as  noted
              below,  all of the fields have been present since at least Linux
              2.6.0.  Some fileds are displayed only if the kernel was config-
              ured  with  various options; those dependencies are noted in the
              list.
              MemTotal %lu
                     Total usable RAM (i.e. physical RAM minus a few  reserved
                     bits and the kernel binary code).
              MemFree %lu
                     The sum of LowFree+HighFree.
              Buffers %lu
                     Relatively  temporary  storage  for  raw disk blocks that
                     shouldn't get tremendously large (20MB or so).
              Cached %lu
                     In-memory cache for files read from the  disk  (the  page
                     cache).  Doesn't include SwapCached.
              SwapCached %lu
                     Memory  that once was swapped out, is swapped back in but
                     still also is in the swap file.  (If memory  pressure  is
                     high,  these  pages  don't  need  to be swapped out again
                     because they are already in the swap  file.   This  saves
                     I/O.)
              Active %lu
                     Memory  that  has been used more recently and usually not
                     reclaimed unless absolutely necessary.
              Inactive %lu
                     Memory which has been less recently  used.   It  is  more
                     eligible to be reclaimed for other purposes.
              Active(anon) %lu (since Linux 2.6.28)
                     [To be documented.]
              Inactive(anon) %lu (since Linux 2.6.28)
                     [To be documented.]
              Active(file) %lu (since Linux 2.6.28)
                     [To be documented.]
              Inactive(file) %lu (since Linux 2.6.28)
                     [To be documented.]
              Unevictable %lu (since Linux 2.6.28)
                     (From  Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU was
                     required.)  [To be documented.]
              Mlocked %lu (since Linux 2.6.28)
                     (From Linux 2.6.28 to 2.6.30, CONFIG_UNEVICTABLE_LRU  was
                     required.)  [To be documented.]
              HighTotal %lu
                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                     Total amount of highmem.  Highmem  is  all  memory  above
                     ~860MB  of physical memory.  Highmem areas are for use by
                     user-space programs, or for the page cache.   The  kernel
                     must  use  tricks to access this memory, making it slower
                     to access than lowmem.
              HighFree %lu
                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                     Amount of free highmem.
              LowTotal %lu
                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                     Total amount of lowmem.  Lowmem is memory  which  can  be
                     used  for everything that highmem can be used for, but it
                     is also available for the kernel's use for its  own  data
                     structures.   Among many other things, it is where every-
                     thing from Slab is allocated.   Bad  things  happen  when
                     you're out of lowmem.
              LowFree %lu
                     (Starting with Linux 2.6.19, CONFIG_HIGHMEM is required.)
                     Amount of free lowmem.
              MmapCopy %lu (since Linux 2.6.29)
                     (CONFIG_MMU is required.)  [To be documented.]
              SwapTotal %lu
                     Total amount of swap space available.
              SwapFree %lu
                     Amount of swap space that is currently unused.
              Dirty %lu
                     Memory which is waiting to get written back to the disk.
              Writeback %lu
                     Memory which is actively being written back to the disk.
              AnonPages %lu (since Linux 2.6.18)
                     Non-file backed pages mapped into user-space page tables.
              Mapped %lu
                     Files which have been mmaped, such as libraries.
              Shmem %lu (since Linux 2.6.32)
                     [To be documented.]
              Slab %lu
                     In-kernel data structures cache.
              SReclaimable %lu (since Linux 2.6.19)
                     Part of Slab, that might be reclaimed, such as caches.
              SUnreclaim %lu (since Linux 2.6.19)
                     Part of Slab, that cannot be reclaimed  on  memory  pres-
                     sure.
              KernelStack %lu (since Linux 2.6.32)
                     Amount of memory allocated to kernel stacks.
              PageTables %lu (since Linux 2.6.18)
                     Amount  of  memory  dedicated to the lowest level of page
                     tables.
              Quicklists %lu (since Linux 2.6.27)
                     (CONFIG_QUICKLIST is required.)  [To be documented.]
              NFS_Unstable %lu (since Linux 2.6.18)
                     NFS pages sent to the server, but not  yet  committed  to
                     stable storage.
              Bounce %lu (since Linux 2.6.18)
                     Memory used for block device "bounce buffers".
              WritebackTmp %lu (since Linux 2.6.26)
                     Memory used by FUSE for temporary writeback buffers.
              CommitLimit %lu (since Linux 2.6.10)
                     Based  on  the  overcommit ratio ('vm.overcommit_ratio'),
                     this is the total amount of  memory  currently  available
                     to  be allocated on the system.  This limit is adhered to
                     only if strict overcommit accounting is enabled  (mode  2
                     in  /proc/sys/vm/overcommit_ratio).   The  CommitLimit is
                     calculated using the following formula:
                         CommitLimit = (overcommit_ratio  *  Physical  RAM)  +
                     Swap
                     For example, on a system with 1GB of physical RAM and 7GB
                     of swap with  a  overcommit_ratio  of  30,  this  formula
                     yields a CommitLimit of 7.3GB.  For more details, see the
                     memory overcommit documentation in the kernel source file
                     Documentation/vm/overcommit-accounting.
              Committed_AS %lu
                     The  amount  of memory presently allocated on the system.
                     The committed memory is a sum of all of the memory  which
                     has  been allocated by processes, even if it has not been
                     "used" by them as of yet.  A process which allocates  1GB
                     of  memory (using malloc(3) or similar), but touches only
                     300MB of that memory will show up as using only 300MB  of
                     memory even if it has the address space allocated for the
                     entire 1GB.  This 1GB is memory which has  been  "commit-
                     ted"  to  by  the  VM  and can be used at any time by the
                     allocating application.  With strict  overcommit  enabled
                     on  the  system  (mode 2 /proc/sys/vm/overcommit_memory),
                     allocations which would exceed the CommitLimit  (detailed
                     above)  will  not  be  permitted.   This is useful if one
                     needs to guarantee that processes will not  fail  due  to
                     lack  of  memory  once  that memory has been successfully
                     allocated.
              VmallocTotal %lu
                     Total size of vmalloc memory area.
              VmallocUsed %lu
                     Amount of vmalloc area which is used.
              VmallocChunk %lu
                     Largest contiguous block of vmalloc area which is free.
              HardwareCorrupted %lu (since Linux 2.6.32)
                     (CONFIG_MEMORY_FAILURE is required.)  [To be documented.]
              AnonHugePages %lu (since Linux 2.6.38)
                     (CONFIG_TRANSPARENT_HUGEPAGE  is   required.)    Non-file
                     backed huge pages mapped into user-space page tables.
              HugePages_Total %lu
                     (CONFIG_HUGETLB_PAGE  is required.)  The size of the pool
                     of huge pages.
              HugePages_Free %lu
                     (CONFIG_HUGETLB_PAGE is required.)  The  number  of  huge
                     pages in the pool that are not yet allocated.
              HugePages_Rsvd %lu (since Linux 2.6.17)
                     (CONFIG_HUGETLB_PAGE is required.)  This is the number of
                     huge pages for which a commitment to  allocate  from  the
                     pool  has been made, but no allocation has yet been made.
                     These reserved huge pages guarantee that  an  application
                     will  be  able  to  allocate a huge page from the pool of
                     huge pages at fault time.
              HugePages_Surp %lu (since Linux 2.6.24)
                     (CONFIG_HUGETLB_PAGE is required.)  This is the number of
                     huge   pages   in   the   pool   above   the   value   in
                     /proc/sys/vm/nr_hugepages.  The maximum number of surplus
                     huge  pages  is  controlled  by  /proc/sys/vm/nr_overcom-
                     mit_hugepages.
              Hugepagesize %lu
                     (CONFIG_HUGETLB_PAGE is  required.)   The  size  of  huge
                     pages.
       /proc/modules
              A  text list of the modules that have been loaded by the system.
              See also lsmod(8).
       /proc/mounts
              Before kernel 2.4.19, this file was a list of all the file  sys-
              tems  currently mounted on the system.  With the introduction of
              per-process mount namespaces in Linux 2.4.19, this file became a
              link  to  /proc/self/mounts, which lists the mount points of the
              process's own mount namespace.  The format of this file is docu-
              mented in fstab(5).
       /proc/mtrr
              Memory  Type  Range Registers.  See the Linux kernel source file
              Documentation/mtrr.txt for details.
       /proc/net
              various net pseudo-files, all of which give the status  of  some
              part  of the networking layer.  These files contain ASCII struc-
              tures and are, therefore, readable with  cat(1).   However,  the
              standard  netstat(8) suite provides much cleaner access to these
              files.
       /proc/net/arp
              This holds an ASCII readable dump of the kernel ARP  table  used
              for  address resolutions.  It will show both dynamically learned
              and preprogrammed ARP entries.  The format is:
        IP address     HW type   Flags     HW address          Mask   Device
        192.168.0.50   0x1       0x2       00:50:BF:25:68:F3   *      eth0
        192.168.0.250  0x1       0xc       00:00:00:00:00:00   *      eth0
              Here "IP address" is the IPv4 address of the machine and the "HW
              type"  is  the  hardware  type of the address from RFC 826.  The
              flags are the internal flags of the ARP structure (as defined in
              /usr/include/linux/if_arp.h)  and  the  "HW address" is the data
              link layer mapping for that IP address if it is known.
       /proc/net/dev
              The dev pseudo-file contains network device status  information.
              This  gives  the number of received and sent packets, the number
              of errors and collisions and other basic statistics.  These  are
              used  by  the  ifconfig(8) program to report device status.  The
              format is:
 Inter-|   Receive                                                |  Transmit
  face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
     lo: 2776770   11307    0    0    0     0          0         0  2776770   11307    0    0    0     0       0          0
   eth0: 1215645    2751    0    0    0     0          0         0  1782404    4324    0    0    0   427       0          0
   ppp0: 1622270    5552    1    0    0     0          0         0   354130    5669    0    0    0     0       0          0
   tap0:    7714      81    0    0    0     0          0         0     7714      81    0    0    0     0       0          0
       /proc/net/dev_mcast
              Defined in /usr/src/linux/net/core/dev_mcast.c:
                   indx interface_name  dmi_u dmi_g dmi_address
                   2    eth0            1     0     01005e000001
                   3    eth1            1     0     01005e000001
                   4    eth2            1     0     01005e000001
       /proc/net/igmp
              Internet    Group    Management    Protocol.      Defined     in
              /usr/src/linux/net/core/igmp.c.
       /proc/net/rarp
              This  file uses the same format as the arp file and contains the
              current reverse mapping database used to provide rarp(8) reverse
              address  lookup  services.   If  RARP is not configured into the
              kernel, this file will not be present.
       /proc/net/raw
              Holds a dump of the RAW socket table.  Much of  the  information
              is  not of use apart from debugging.  The "sl" value is the ker-
              nel hash slot for the socket, the "local_address" is  the  local
              address  and  protocol number pair.  "St" is the internal status
              of the socket.  The "tx_queue" and "rx_queue" are  the  outgoing
              and  incoming  data  queue in terms of kernel memory usage.  The
              "tr", "tm->when", and "rexmits" fields are not used by RAW.  The
              "uid"  field  holds  the  effective  UID  of  the creator of the
              socket.
       /proc/net/snmp
              This file holds the ASCII data needed for the IP, ICMP, TCP, and
              UDP management information bases for an SNMP agent.
       /proc/net/tcp
              Holds  a  dump of the TCP socket table.  Much of the information
              is not of use apart from debugging.  The "sl" value is the  ker-
              nel  hash  slot for the socket, the "local_address" is the local
              address and port number pair.  The "rem_address" is  the  remote
              address and port number pair (if connected).  "St" is the inter-
              nal status of the socket.  The "tx_queue" and "rx_queue" are the
              outgoing  and  incoming  data  queue  in  terms of kernel memory
              usage.  The "tr", "tm->when", and "rexmits" fields hold internal
              information  of  the kernel socket state and are only useful for
              debugging.  The "uid" field holds the effective UID of the  cre-
              ator of the socket.
       /proc/net/udp
              Holds  a  dump of the UDP socket table.  Much of the information
              is not of use apart from debugging.  The "sl" value is the  ker-
              nel  hash  slot for the socket, the "local_address" is the local
              address and port number pair.  The "rem_address" is  the  remote
              address  and port number pair (if connected). "St" is the inter-
              nal status of the socket.  The "tx_queue" and "rx_queue" are the
              outgoing  and  incoming  data  queue  in  terms of kernel memory
              usage.  The "tr", "tm->when", and "rexmits" fields are not  used
              by  UDP.  The "uid" field holds the effective UID of the creator
              of the socket.  The format is:
 sl  local_address rem_address   st tx_queue rx_queue tr rexmits  tm->when uid
  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0
       /proc/net/unix
              Lists the UNIX domain sockets  present  within  the  system  and
              their status.  The format is:
              Num RefCount Protocol Flags    Type St Path
               0: 00000002 00000000 00000000 0001 03
               1: 00000001 00000000 00010000 0001 01 /dev/printer
              Here  "Num"  is  the kernel table slot number, "RefCount" is the
              number of users of the socket, "Protocol" is currently always 0,
              "Flags"  represent  the internal kernel flags holding the status
              of the socket.  Currently, type is always "1" (UNIX domain data-
              gram  sockets are not yet supported in the kernel).  "St" is the
              internal state of the socket and Path is the bound path (if any)
              of the socket.
       /proc/partitions
              Contains  major  and  minor numbers of each partition as well as
              number of blocks and partition name.
       /proc/pci
              This is a listing of all PCI devices found  during  kernel  ini-
              tialization and their configuration.
              This  file has been deprecated in favor of a new /proc interface
              for PCI  (/proc/bus/pci).   It  became  optional  in  Linux  2.2
              (available  with CONFIG_PCI_OLD_PROC set at kernel compilation).
              It became once more nonoptionally enabled in Linux  2.4.   Next,
              it  was  deprecated  in  Linux  2.6  (still  available with CON-
              FIG_PCI_LEGACY_PROC set), and finally removed  altogether  since
              Linux 2.6.17.
       /proc/profile (since Linux 2.4)
              This file is present only if the kernel was booted with the pro-
              file=1 command-line option.  It exposes kernel profiling  infor-
              mation  in  a  binary format for use by readprofile(1).  Writing
              (e.g., an empty string) to this file resets the profiling  coun-
              ters; on some architectures, writing a binary integer "profiling
              multiplier" of size sizeof(int)  sets  the  profiling  interrupt
              frequency.
       /proc/scsi
              A directory with the scsi mid-level pseudo-file and various SCSI
              low-level driver directories, which contain a file for each SCSI
              host  in  this system, all of which give the status of some part
              of the SCSI IO subsystem.  These files contain ASCII  structures
              and are, therefore, readable with cat(1).
              You  can also write to some of the files to reconfigure the sub-
              system or switch certain features on or off.
       /proc/scsi/scsi
              This is a listing of all SCSI devices known to the kernel.   The
              listing  is  similar  to  the one seen during bootup.  scsi cur-
              rently supports only the add-single-device command which  allows
              root to add a hotplugged device to the list of known devices.
              The command
                  echo 'scsi add-single-device 1 0 5 0' > /proc/scsi/scsi
              will  cause host scsi1 to scan on SCSI channel 0 for a device on
              ID 5 LUN 0.  If there is already a device known on this  address
              or the address is invalid, an error will be returned.
       /proc/scsi/[drivername]
              [drivername]  can  currently  be  NCR53c7xx,  aha152x,  aha1542,
              aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000,
              pas16,  qlogic,  scsi_debug, seagate, t128, u15-24f, ultrastore,
              or wd7000.  These directories show up for all drivers that  reg-
              istered  at  least  one  SCSI HBA.  Every directory contains one
              file per registered host.  Every host-file is  named  after  the
              number the host was assigned during initialization.
              Reading these files will usually show driver and host configura-
              tion, statistics, etc.
              Writing to these files  allows  different  things  on  different
              hosts.   For  example,  with the latency and nolatency commands,
              root can switch on and off command latency measurement  code  in
              the  eata_dma driver.  With the lockup and unlock commands, root
              can control bus lockups simulated by the scsi_debug driver.
       /proc/self
              This directory refers to the process accessing  the  /proc  file
              system,  and  is  identical  to the /proc directory named by the
              process ID of the same process.
       /proc/slabinfo
              Information about kernel caches.  Since Linux 2.6.16  this  file
              is  present  only if the CONFIG_SLAB kernel configuration option
              is enabled.  The columns in /proc/slabinfo are:
                  cache-name
                  num-active-objs
                  total-objs
                  object-size
                  num-active-slabs
                  total-slabs
                  num-pages-per-slab
              See slabinfo(5) for details.
       /proc/stat
              kernel/system statistics.   Varies  with  architecture.   Common
              entries include:
              cpu  3357 0 4313 1362393
                     The   amount  of  time,  measured  in  units  of  USER_HZ
                     (1/100ths  of  a  second  on  most   architectures,   use
                     sysconf(_SC_CLK_TCK) to obtain the right value), that the
                     system spent in various states:
                     user   (1) Time spent in user mode.
                     nice   (2) Time spent in  user  mode  with  low  priority
                            (nice).
                     system (3) Time spent in system mode.
                     idle   (4)  Time  spent  in  the  idle  task.  This value
                            should be USER_HZ times the second  entry  in  the
                            /proc/uptime pseudo-file.
                     iowait (since Linux 2.5.41)
                            (5) Time waiting for I/O to complete.
                     irq (since Linux 2.6.0-test4)
                            (6) Time servicing interrupts.
                     softirq (since Linux 2.6.0-test4)
                            (7) Time servicing softirqs.
                     steal (since Linux 2.6.11)
                            (8)  Stolen time, which is the time spent in other
                            operating systems when running  in  a  virtualized
                            environment
                     guest (since Linux 2.6.24)
                            (9)  Time  spent  running  a virtual CPU for guest
                            operating systems under the control of  the  Linux
                            kernel.
                     guest_nice (since Linux 2.6.33)
                            (10) Time spent running a niced guest (virtual CPU
                            for guest operating systems under the  control  of
                            the Linux kernel).
              page 5741 1808
                     The  number  of  pages the system paged in and the number
                     that were paged out (from disk).
              swap 1 0
                     The number of swap pages that have been  brought  in  and
                     out.
              intr 1462898
                     This  line shows counts of interrupts serviced since boot
                     time, for each of the possible  system  interrupts.   The
                     first  column  is  the  total of all interrupts serviced;
                     each subsequent column is  the  total  for  a  particular
                     interrupt.
              disk_io: (2,0):(31,30,5764,1,2) (3,0):...
                     (major,disk_idx):(noinfo,     read_io_ops,     blks_read,
                     write_io_ops, blks_written)
                     (Linux 2.4 only)
              ctxt 115315
                     The number of context switches that the system underwent.
              btime 769041601
                     boot  time,  in  seconds  since  the  Epoch,   1970-01-01
                     00:00:00 +0000 (UTC).
              processes 86031
                     Number of forks since boot.
              procs_running 6
                     Number  of  processes  in  runnable state.  (Linux 2.5.45
                     onward.)
              procs_blocked 2
                     Number of processes blocked waiting for I/O to  complete.
                     (Linux 2.5.45 onward.)
       /proc/swaps
              Swap areas in use.  See also swapon(8).
       /proc/sys
              This directory (present since 1.3.57) contains a number of files
              and subdirectories corresponding  to  kernel  variables.   These
              variables  can  be  read  and sometimes modified using the /proc
              file system, and the (deprecated) sysctl(2) system call.
       /proc/sys/abi (since Linux 2.4.10)
              This directory may contain files with application binary  infor-
              mation.    See   the   Linux   kernel   source  file  Documenta-
              tion/sysctl/abi.txt for more information.
       /proc/sys/debug
              This directory may be empty.
       /proc/sys/dev
              This  directory  contains  device-specific  information   (e.g.,
              dev/cdrom/info).  On some systems, it may be empty.
       /proc/sys/fs
              This  directory contains the files and subdirectories for kernel
              variables related to file systems.
       /proc/sys/fs/binfmt_misc
              Documentation for files in this directory can be  found  in  the
              Linux kernel sources in Documentation/binfmt_misc.txt.
       /proc/sys/fs/dentry-state (since Linux 2.2)
              This file contains information about the status of the directory
              cache (dcache).   The  file  contains  six  numbers,  nr_dentry,
              nr_unused,   age_limit   (age  in  seconds),  want_pages  (pages
              requested by system) and two dummy values.
              * nr_dentry  is  the  number  of  allocated   dentries   (dcache
                entries).  This field is unused in Linux 2.2.
              * nr_unused is the number of unused dentries.
              * age_limit is the age in seconds after which dcache entries can
                be reclaimed when memory is short.
              * want_pages   is   nonzero   when   the   kernel   has   called
                shrink_dcache_pages() and the dcache isn't pruned yet.
       /proc/sys/fs/dir-notify-enable
              This file can be used to disable or enable the dnotify interface
              described in fcntl(2) on a system-wide basis.  A value of  0  in
              this file disables the interface, and a value of 1 enables it.
       /proc/sys/fs/dquot-max
              This file shows the maximum number of cached disk quota entries.
              On some (2.4) systems, it is not present.  If the number of free
              cached  disk quota entries is very low and you have some awesome
              number of simultaneous system users, you might want to raise the
              limit.
       /proc/sys/fs/dquot-nr
              This  file  shows the number of allocated disk quota entries and
              the number of free disk quota entries.
       /proc/sys/fs/epoll (since Linux 2.6.28)
              This directory contains the file max_user_watches, which can  be
              used  to limit the amount of kernel memory consumed by the epoll
              interface.  For further details, see epoll(7).
       /proc/sys/fs/file-max
              This file defines a system-wide limit  on  the  number  of  open
              files  for  all processes.  (See also setrlimit(2), which can be
              used by a process to set the per-process  limit,  RLIMIT_NOFILE,
              on  the  number of files it may open.)  If you get lots of error
              messages in the kernel log about running  out  of  file  handles
              (look  for "VFS: file-max limit <number> reached"), try increas-
              ing this value:
                  echo 100000 > /proc/sys/fs/file-max
              The kernel constant NR_OPEN imposes an upper limit on the  value
              that may be placed in file-max.
              If  you  increase  /proc/sys/fs/file-max,  be  sure  to increase
              /proc/sys/fs/inode-max  to  3-4   times   the   new   value   of
              /proc/sys/fs/file-max, or you will run out of inodes.
              Privileged  processes  (CAP_SYS_ADMIN) can override the file-max
              limit.
       /proc/sys/fs/file-nr
              This (read-only) file contains  three  numbers:  the  number  of
              allocated  file  handles  (i.e.,  the  number of files presently
              opened); the number of free file handles; and the maximum number
              of file handles (i.e., the same value as /proc/sys/fs/file-max).
              If the number of allocated file handles is close to the maximum,
              you  should  consider increasing the maximum.  Before Linux 2.6,
              the kernel allocated file handles  dynamically,  but  it  didn't
              free  them  again.  Instead the free file handles were kept in a
              list for reallocation; the "free file handles"  value  indicates
              the  size  of  that  list.   A large number of free file handles
              indicates that there was a past peak in the usage of  open  file
              handles.  Since Linux 2.6, the kernel does deallocate freed file
              handles, and the "free file handles" value is always zero.
       /proc/sys/fs/inode-max
              This file contains the maximum number of in-memory  inodes.   On
              some (2.4) systems, it may not be present.  This value should be
              3-4 times larger than the value in file-max, since stdin, stdout
              and network sockets also need an inode to handle them.  When you
              regularly run out of inodes, you need to increase this value.
       /proc/sys/fs/inode-nr
              This file contains the first two values from inode-state.
       /proc/sys/fs/inode-state
              This file contains  seven  numbers:  nr_inodes,  nr_free_inodes,
              preshrink,  and  four  dummy values.  nr_inodes is the number of
              inodes the system has allocated.  This can be slightly more than
              inode-max  because Linux allocates them one page full at a time.
              nr_free_inodes represents the number of free inodes.   preshrink
              is  nonzero  when the nr_inodes > inode-max and the system needs
              to prune the inode list instead of allocating more.
       /proc/sys/fs/inotify (since Linux 2.6.13)
              This     directory     contains     files     max_queued_events,
              max_user_instances,  and  max_user_watches,  that can be used to
              limit the amount of kernel memory consumed by the inotify inter-
              face.  For further details, see inotify(7).
       /proc/sys/fs/lease-break-time
              This file specifies the grace period that the kernel grants to a
              process holding a file lease (fcntl(2)) after it has sent a sig-
              nal to that process notifying it that another process is waiting
              to open the file.  If the lease holder does not remove or  down-
              grade  the  lease  within this grace period, the kernel forcibly
              breaks the lease.
       /proc/sys/fs/leases-enable
              This  file  can  be  used  to  enable  or  disable  file  leases
              (fcntl(2))  on  a  system-wide basis.  If this file contains the
              value 0, leases are disabled.  A nonzero value enables leases.
       /proc/sys/fs/mqueue (since Linux 2.6.6)
              This  directory  contains  files   msg_max,   msgsize_max,   and
              queues_max,  controlling  the  resources  used  by POSIX message
              queues.  See mq_overview(7) for details.
       /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid
              These files allow you to change the value of the fixed  UID  and
              GID.   The  default  is  65534.   Some file systems support only
              16-bit UIDs and GIDs, although in Linux UIDs  and  GIDs  are  32
              bits.   When  one  of  these file systems is mounted with writes
              enabled, any UID or GID that would exceed 65535 is translated to
              the overflow value before being written to disk.
       /proc/sys/fs/pipe-max-size (since Linux 2.6.35)
              The  value  in  this file defines an upper limit for raising the
              capacity of a pipe using the  fcntl(2)  F_SETPIPE_SZ  operation.
              This  limit applies only to unprivileged processes.  The default
              value for this file is 1,048,576.  The value  assigned  to  this
              file  may  be  rounded  upward,  to  reflect  the value actually
              employed for a  convenient  implementation.   To  determine  the
              rounded-up  value,  display  the  contents  of  this  file after
              assigning a value to it.  The minimum value that can be assigned
              to this file is the system page size.
       /proc/sys/fs/protected_hardlinks (since Linux 3.6)
              When  the value in this file is 0, no restrictions are placed on
              the creation of hard links (i.e., this is the historical  behav-
              iour  before  Linux  3.6).   When the value in this file is 1, a
              hard link can be created to a target file only  if  one  of  the
              following conditions is true:
              *  The caller has the CAP_FOWNER capability.
              *  The  file system UID of the process creating the link matches
                 the owner (UID) of the target file (as described  in  creden-
                 tials(7), a process's file system UID is normally the same as
                 its effective UID).
              *  All of the following conditions are true:
                  o  the target is a regular file;
                  o  the target file does not have its set-user-ID  permission
                     bit enabled;
                  o  the  target  file does not have both its set-group-ID and
                     group-executable permission bits enabled; and
                  o  the caller has permission to read and  write  the  target
                     file  (either  via the file's permissions mask or because
                     it has suitable capabilities).
              The default value in this file is 0.  Setting  the  value  to  1
              prevents a longstanding class of security issues caused by hard-
              link-based time-of-check, time-of-use races, most commonly  seen
              in  world-writable  directories such as /tmp.  The common method
              of exploiting this flaw is to cross  privilege  boundaries  when
              following a given hard link (i.e., a root process follows a hard
              link created by another user).  Additionally, on systems without
              separated  partitions,  this stops unauthorized users from "pin-
              ning" vulnerable  set-user-ID  and  set-group-ID  files  against
              being  upgraded  by  the  administrator,  or  linking to special
              files.
       /proc/sys/fs/protected_symlinks (since Linux 3.6)
              When the value in this file is 0, no restrictions are placed  on
              following symbolic links (i.e., this is the historical behaviour
              before Linux 3.6).  When the value in this file is  1,  symbolic
              links are followed only in the following circumstances:
              *  the file system UID of the process following the link matches
                 the owner (UID) of the symbolic link (as described in creden-
                 tials(7), a process's file system UID is normally the same as
                 its effective UID);
              *  the link is not in a sticky world-writable directory; or
              *  the symbolic link and and its parent directory have the  same
                 owner (UID)
              A  system  call  that fails to follow a symbolic link because of
              the above restrictions returns the error EACCES in errno.
              The default value in this file is 0.  Setting  the  value  to  1
              avoids a longstanding class of security issues based on time-of-
              check, time-of-use races when accessing symbolic links.
       /proc/sys/fs/suid_dumpable (since Linux 2.6.13)
              The value in this file determines whether core  dump  files  are
              produced  for  set-user-ID  or otherwise protected/tainted bina-
              ries.  Three different integer values can be specified:
              0 (default)
                     This provides the traditional (pre-Linux  2.6.13)  behav-
                     ior.   A  core  dump  will  not be produced for a process
                     which has changed  credentials  (by  calling  seteuid(2),
                     setgid(2),  or  similar, or by executing a set-user-ID or
                     set-group-ID program) or whose binary does not have  read
                     permission enabled.
              1 ("debug")
                     All  processes dump core when possible.  The core dump is
                     owned by the file system user ID of the  dumping  process
                     and  no security is applied.  This is intended for system
                     debugging situations only.  Ptrace is unchecked.
              2 ("suidsafe")
                     Any binary which normally would not be  dumped  (see  "0"
                     above)  is dumped readable by root only.  This allows the
                     user to remove the core dump file but  not  to  read  it.
                     For  security  reasons  core  dumps in this mode will not
                     overwrite one another  or  other  files.   This  mode  is
                     appropriate  when  administrators are attempting to debug
                     problems in a normal environment.
                     Additionally, since Linux 3.6, /proc/sys/kernel/core_pat-
                     tern  must  either be an absolute pathname or a pipe com-
                     mand, as detailed in core(5).  Warnings will  be  written
                     to  the  kernel log if core_pattern does not follow these
                     rules, and no core dump will be produced.
       /proc/sys/fs/super-max
              This file controls the maximum number of superblocks,  and  thus
              the  maximum number of mounted file systems the kernel can have.
              You need increase only super-max if you need to mount more  file
              systems than the current value in super-max allows you to.
       /proc/sys/fs/super-nr
              This file contains the number of file systems currently mounted.
       /proc/sys/kernel
              This  directory  contains  files  controlling  a range of kernel
              parameters, as described below.
       /proc/sys/kernel/acct
              This file contains three numbers: highwater, lowwater, and  fre-
              quency.  If BSD-style process accounting is enabled these values
              control its behavior.  If free space on file  system  where  the
              log  lives  goes below lowwater percent accounting suspends.  If
              free space gets  above  highwater  percent  accounting  resumes.
              frequency  determines  how often the kernel checks the amount of
              free space (value is in seconds).  Default values are 4,  2  and
              30.   That  is,  suspend accounting if 2% or less space is free;
              resume it if 4% or more  space  is  free;  consider  information
              about amount of free space valid for 30 seconds.
       /proc/sys/kernel/cap_last_cap (since Linux 3.2)
              See capabilities(7).
       /proc/sys/kernel/cap-bound (from Linux 2.2 to 2.6.24)
              This  file holds the value of the kernel capability bounding set
              (expressed as a signed  decimal  number).   This  set  is  ANDed
              against   the   capabilities   permitted  to  a  process  during
              execve(2).  Starting with Linux 2.6.25, the system-wide capabil-
              ity  bounding  set disappeared, and was replaced by a per-thread
              bounding set; see capabilities(7).
       /proc/sys/kernel/core_pattern
              See core(5).
       /proc/sys/kernel/core_uses_pid
              See core(5).
       /proc/sys/kernel/ctrl-alt-del
              This file controls the handling of Ctrl-Alt-Del  from  the  key-
              board.   When  the  value  in  this  file  is 0, Ctrl-Alt-Del is
              trapped and sent to the init(8) program  to  handle  a  graceful
              restart.   When the value is greater than zero, Linux's reaction
              to a Vulcan Nerve Pinch (tm) will be an immediate reboot,  with-
              out  even syncing its dirty buffers.  Note: when a program (like
              dosemu) has the keyboard in  "raw"  mode,  the  ctrl-alt-del  is
              intercepted by the program before it ever reaches the kernel tty
              layer, and it's up to the program to decide what to do with it.
       /proc/sys/kernel/dmesg_restrict (since Linux 2.6.37)
              The value in this file determines who can see kernel syslog con-
              tents.   A  value of 0 in this file imposes no restrictions.  If
              the value is 1, only privileged users can read the  kernel  sys-
              log.   (See  syslog(2) for more details.)  Since Linux 3.4, only
              users with the CAP_SYS_ADMIN capability may change the value  in
              this file.
       /proc/sys/kernel/domainname and /proc/sys/kernel/hostname
              can  be  used  to  set the NIS/YP domainname and the hostname of
              your box in exactly the same way as the  commands  domainname(1)
              and hostname(1), that is:
                  # echo 'darkstar' > /proc/sys/kernel/hostname
                  # echo 'mydomain' > /proc/sys/kernel/domainname
              has the same effect as
                  # hostname 'darkstar'
                  # domainname 'mydomain'
              Note,  however, that the classic darkstar.frop.org has the host-
              name "darkstar" and DNS (Internet Domain Name Server) domainname
              "frop.org", not to be confused with the NIS (Network Information
              Service) or YP (Yellow  Pages)  domainname.   These  two  domain
              names  are  in general different.  For a detailed discussion see
              the hostname(1) man page.
       /proc/sys/kernel/hotplug
              This file contains the path for the hotplug policy  agent.   The
              default value in this file is /sbin/hotplug.
       /proc/sys/kernel/htab-reclaim
              (PowerPC  only) If this file is set to a nonzero value, the Pow-
              erPC htab (see kernel  file  Documentation/powerpc/ppc_htab.txt)
              is pruned each time the system hits the idle loop.
       /proc/sys/kernel/kptr_restrict (since Linux 2.6.38)
              The  value  in this file determines whether kernel addresses are
              exposed via /proc files and other interfaces.  A value of  0  in
              this  file  imposes  no restrictions.  If the value is 1, kernel
              pointers printed using the %pK format specifier will be replaced
              with  zeros  unless  the user has the CAP_SYSLOG capability.  If
              the value is 2, kernel pointers printed  using  the  %pK  format
              specifier  will  be replaced with zeros regardless of the user's
              capabilities.  The initial default value for this  file  was  1,
              but  the  default was changed to 0 in Linux 2.6.39.  Since Linux
              3.4, only users with the CAP_SYS_ADMIN capability can change the
              value in this file.
       /proc/sys/kernel/l2cr
              (PowerPC  only)  This  file contains a flag that controls the L2
              cache of G3 processor boards.  If  0,  the  cache  is  disabled.
              Enabled if nonzero.
       /proc/sys/kernel/modprobe
              This  file  contains the path for the kernel module loader.  The
              default value is /sbin/modprobe.  The file is  present  only  if
              the  kernel  is  built  with  the CONFIG_MODULES (CONFIG_KMOD in
              Linux 2.6.26 and earlier) option enabled.  It  is  described  by
              the  Linux  kernel  source  file Documentation/kmod.txt (present
              only in kernel 2.4 and earlier).
       /proc/sys/kernel/modules_disabled (since Linux 2.6.31)
              A toggle value indicating if modules are allowed to be loaded in
              an  otherwise  modular kernel.  This toggle defaults to off (0),
              but can be set true (1).  Once  true,  modules  can  be  neither
              loaded nor unloaded, and the toggle cannot be set back to false.
              The file is present only if the kernel is built  with  the  CON-
              FIG_MODULES option enabled.
       /proc/sys/kernel/msgmax
              This  file  defines  a  system-wide limit specifying the maximum
              number of bytes in a single message written on a System  V  mes-
              sage queue.
       /proc/sys/kernel/msgmni (since Linux 2.4)
              This file defines the system-wide limit on the number of message
              queue identifiers.
       /proc/sys/kernel/msgmnb
              This file defines a system-wide parameter used to initialize the
              msg_qbytes setting for subsequently created message queues.  The
              msg_qbytes setting specifies the maximum number  of  bytes  that
              may be written to the message queue.
       /proc/sys/kernel/ostype and /proc/sys/kernel/osrelease
              These files give substrings of /proc/version.
       /proc/sys/kernel/overflowgid and /proc/sys/kernel/overflowuid
              These  files  duplicate  the  files /proc/sys/fs/overflowgid and
              /proc/sys/fs/overflowuid.
       /proc/sys/kernel/panic
              This  file  gives  read/write  access  to  the  kernel  variable
              panic_timeout.   If  this  is  zero,  the  kernel will loop on a
              panic; if nonzero it indicates that the kernel should autoreboot
              after  this number of seconds.  When you use the software watch-
              dog device driver, the recommended setting is 60.
       /proc/sys/kernel/panic_on_oops (since Linux 2.5.68)
              This file controls the kernel's behavior when an oops or BUG  is
              encountered.   If this file contains 0, then the system tries to
              continue operation.  If it contains 1, then the system delays  a
              few  seconds  (to give klogd time to record the oops output) and
              then panics.  If the /proc/sys/kernel/panic file is also nonzero
              then the machine will be rebooted.
       /proc/sys/kernel/pid_max (since Linux 2.5.34)
              This  file  specifies the value at which PIDs wrap around (i.e.,
              the value in this file is one greater  than  the  maximum  PID).
              The  default  value  for  this  file, 32768, results in the same
              range of PIDs as on earlier kernels.  On 32-bit platforms, 32768
              is  the  maximum  value for pid_max.  On 64-bit systems, pid_max
              can be set to any value up to 2^22 (PID_MAX_LIMIT, approximately
              4 million).
       /proc/sys/kernel/powersave-nap (PowerPC only)
              This file contains a flag.  If set, Linux-PPC will use the "nap"
              mode of powersaving, otherwise the "doze" mode will be used.
       /proc/sys/kernel/printk
              The four values in this file are console_loglevel,  default_mes-
              sage_loglevel,     minimum_console_level,    and    default_con-
              sole_loglevel.  These values influence  printk()  behavior  when
              printing or logging error messages.  See syslog(2) for more info
              on the different loglevels.  Messages  with  a  higher  priority
              than  console_loglevel will be printed to the console.  Messages
              without an explicit  priority  will  be  printed  with  priority
              default_message_level.   minimum_console_loglevel is the minimum
              (highest)  value  to  which   console_loglevel   can   be   set.
              default_console_loglevel   is   the   default   value  for  con-
              sole_loglevel.
       /proc/sys/kernel/pty (since Linux 2.6.4)
              This directory contains two files relating to the number of UNIX
              98 pseudoterminals (see pts(4)) on the system.
       /proc/sys/kernel/pty/max
              This file defines the maximum number of pseudoterminals.
       /proc/sys/kernel/pty/nr
              This  read-only file indicates how many pseudoterminals are cur-
              rently in use.
       /proc/sys/kernel/random
              This directory contains various parameters controlling the oper-
              ation of the file /dev/random.  See random(4) for further infor-
              mation.
       /proc/sys/kernel/real-root-dev
              This file is documented in the Linux kernel source file Documen-
              tation/initrd.txt.
       /proc/sys/kernel/reboot-cmd (Sparc only)
              This  file  seems  to  be a way to give an argument to the SPARC
              ROM/Flash boot loader.  Maybe  to  tell  it  what  to  do  after
              rebooting?
       /proc/sys/kernel/rtsig-max
              (Only  in  kernels  up to and including 2.6.7; see setrlimit(2))
              This file can be used to tune the maximum number of POSIX  real-
              time (queued) signals that can be outstanding in the system.
       /proc/sys/kernel/rtsig-nr
              (Only  in  kernels  up to and including 2.6.7.)  This file shows
              the number POSIX real-time signals currently queued.
       /proc/sys/kernel/sched_rr_timeslice_ms (since Linux 3.9)
              See sched_rr_get_interval(2).
       /proc/sys/kernel/sem (since Linux 2.4)
              This file contains 4 numbers defining limits for  System  V  IPC
              semaphores.  These fields are, in order:
              SEMMSL  The maximum semaphores per semaphore set.
              SEMMNS  A  system-wide  limit on the number of semaphores in all
                      semaphore sets.
              SEMOPM  The maximum number of operations that may  be  specified
                      in a semop(2) call.
              SEMMNI  A  system-wide  limit on the maximum number of semaphore
                      identifiers.
       /proc/sys/kernel/sg-big-buff
              This file shows the size of the generic SCSI device (sg) buffer.
              You  can't  tune it just yet, but you could change it at compile
              time by editing include/scsi/sg.h  and  changing  the  value  of
              SG_BIG_BUFF.   However,  there shouldn't be any reason to change
              this value.
       /proc/sys/kernel/shm_rmid_forced (since Linux 3.1)
              If this file is set to 1, all System V  shared  memory  segments
              will be marked for destruction as soon as the number of attached
              processes falls to zero; in other words, it is no longer  possi-
              ble to create shared memory segments that exist independently of
              any attached process.
              The effect is as though a shmctl(2) IPC_RMID is performed on all
              existing  segments as well as all segments created in the future
              (until this file is reset to 0).  Note  that  existing  segments
              that  are  attached  to no process will be immediately destroyed
              when this file is set to  1.   Setting  this  option  will  also
              destroy  segments  that  were  created, but never attached, upon
              termination  of  the  process  that  created  the  segment  with
              shmget(2).
              Setting  this file to 1 provides a way of ensuring that all Sys-
              tem V shared memory segments are counted  against  the  resource
              usage  and  resource limits (see the description of RLIMIT_AS in
              getrlimit(2)) of at least one process.
              Because setting this file to 1 produces behavior  that  is  non-
              standard and could also break existing applications, the default
              value in this file is 0.  Only set this file to 1 if you have  a
              good  understanding  of  the semantics of the applications using
              System V shared memory on your system.
       /proc/sys/kernel/shmall
              This file contains the system-wide limit on the total number  of
              pages of System V shared memory.
       /proc/sys/kernel/shmmax
              This file can be used to query and set the run-time limit on the
              maximum (System V IPC) shared memory segment size  that  can  be
              created.   Shared memory segments up to 1GB are now supported in
              the kernel.  This value defaults to SHMMAX.
       /proc/sys/kernel/shmmni (since Linux 2.4)
              This file specifies the system-wide maximum number of  System  V
              shared memory segments that can be created.
       /proc/sys/kernel/sysrq
              This  file  controls  the functions allowed to be invoked by the
              SysRq key.  By default, the file contains 1 meaning  that  every
              possible  SysRq  request  is  allowed (in older kernel versions,
              SysRq was disabled by default, and you were required to specifi-
              cally enable it at run-time, but this is not the case any more).
              Possible values in this file are:
                 0 - disable sysrq completely
                 1 - enable all functions of sysrq
                >1 - bit mask of allowed sysrq functions, as follows:
                        2 - enable control of console logging level
                        4 - enable control of keyboard (SAK, unraw)
                        8 - enable debugging dumps of processes etc.
                       16 - enable sync command
                       32 - enable remount read-only
                       64 - enable signalling of processes (term,  kill,  oom-
              kill)
                      128 - allow reboot/poweroff
                      256 - allow nicing of all real-time tasks
              This  file is present only if the CONFIG_MAGIC_SYSRQ kernel con-
              figuration option is enabled.  For further details see the Linux
              kernel source file Documentation/sysrq.txt.
       /proc/sys/kernel/version
              This file contains a string like:
                  #5 Wed Feb 25 21:49:24 MET 1998
              The  "#5"  means  that  this is the fifth kernel built from this
              source base and the date behind it indicates the time the kernel
              was built.
       /proc/sys/kernel/threads-max (since Linux 2.3.11)
              This  file  specifies  the  system-wide  limit  on the number of
              threads (tasks) that can be created on the system.
       /proc/sys/kernel/zero-paged (PowerPC only)
              This file contains a flag.  When  enabled  (nonzero),  Linux-PPC
              will  pre-zero  pages  in  the  idle  loop, possibly speeding up
              get_free_pages.
       /proc/sys/net
              This directory contains networking stuff.  Explanations for some
              of  the  files  under  this directory can be found in tcp(7) and
              ip(7).
       /proc/sys/net/core/somaxconn
              This file defines a ceiling value for the  backlog  argument  of
              listen(2); see the listen(2) manual page for details.
       /proc/sys/proc
              This directory may be empty.
       /proc/sys/sunrpc
              This  directory  supports  Sun remote procedure call for network
              file system (NFS).  On some systems, it is not present.
       /proc/sys/vm
              This directory contains files for memory management tuning, buf-
              fer and cache management.
       /proc/sys/vm/drop_caches (since Linux 2.6.16)
              Writing  to  this  file  causes the kernel to drop clean caches,
              dentries and inodes from memory, causing that memory  to  become
              free.
              To  free  pagecache,  use  echo 1 > /proc/sys/vm/drop_caches; to
              free dentries and inodes, use echo 2 > /proc/sys/vm/drop_caches;
              to   free   pagecache,   dentries  and  inodes,  use  echo  3  >
              /proc/sys/vm/drop_caches.
              Because this is a nondestructive operation and dirty objects are
              not freeable, the user should run sync(8) first.
       /proc/sys/vm/legacy_va_layout (since Linux 2.6.9)
              If  nonzero, this disables the new 32-bit memory-mapping layout;
              the kernel will use the legacy (2.4) layout for all processes.
       /proc/sys/vm/memory_failure_early_kill (since Linux 2.6.32)
              Control how to kill processes when an uncorrected  memory  error
              (typically a 2-bit error in a memory module) that cannot be han-
              dled by the kernel is detected in the  background  by  hardware.
              In some cases (like the page still having a valid copy on disk),
              the kernel will handle the failure transparently without affect-
              ing  any applications.  But if there is no other up-to-date copy
              of the data, it will kill processes to prevent any data  corrup-
              tions from propagating.
              The file has one of the following values:
              1:  Kill  all  processes that have the corrupted-and-not-reload-
                  able page mapped as soon  as  the  corruption  is  detected.
                  Note  this  is  not supported for a few types of pages, like
                  kernel internally allocated data  or  the  swap  cache,  but
                  works for the majority of user pages.
              0:  Only  unmap  the  corrupted page from all processes and kill
                  only a process that tries to access it.
              The kill is performed using a SIGBUS signal with si_code set  to
              BUS_MCEERR_AO.   Processes  can handle this if they want to; see
              sigaction(2) for more details.
              This feature is  active  only  on  architectures/platforms  with
              advanced  machine  check  handling  and  depends on the hardware
              capabilities.
              Applications can override the memory_failure_early_kill  setting
              individually with the prctl(2) PR_MCE_KILL operation.
              Only  present  if  the  kernel  was  configured with CONFIG_MEM-
              ORY_FAILURE.
       /proc/sys/vm/memory_failure_recovery (since Linux 2.6.32)
              Enable memory failure recovery (when supported by the platform)
              1:  Attempt recovery.
              0:  Always panic on a memory failure.
              Only present if  the  kernel  was  configured  with  CONFIG_MEM-
              ORY_FAILURE.
       /proc/sys/vm/oom_dump_tasks (since Linux 2.6.25)
              Enables a system-wide task dump (excluding kernel threads) to be
              produced when the kernel  performs  an  OOM-killing.   The  dump
              includes  the  following  information  for  each  task  (thread,
              process): thread ID, real user ID, thread group ID (process ID),
              virtual memory size, resident set size, the CPU that the task is
              scheduled  on,   oom_adj   score   (see   the   description   of
              /proc/[pid]/oom_adj),  and  command  name.   This  is helpful to
              determine why the OOM-killer was invoked  and  to  identify  the
              rogue task that caused it.
              If this contains the value zero, this information is suppressed.
              On very large systems with thousands of tasks,  it  may  not  be
              feasible  to  dump  the  memory  state information for each one.
              Such systems should not be forced to incur a performance penalty
              in OOM situations when the information may not be desired.
              If  this  is  set to nonzero, this information is shown whenever
              the OOM-killer actually kills a memory-hogging task.
              The default value is 0.
       /proc/sys/vm/oom_kill_allocating_task (since Linux 2.6.24)
              This enables or disables killing the OOM-triggering task in out-
              of-memory situations.
              If  this  is  set  to zero, the OOM-killer will scan through the
              entire tasklist and select a task based on heuristics  to  kill.
              This  normally selects a rogue memory-hogging task that frees up
              a large amount of memory when killed.
              If this is set to nonzero, the OOM-killer simply kills the  task
              that  triggered the out-of-memory condition.  This avoids a pos-
              sibly expensive tasklist scan.
              If /proc/sys/vm/panic_on_oom is  nonzero,  it  takes  precedence
              over  whatever  value  is used in /proc/sys/vm/oom_kill_allocat-
              ing_task.
              The default value is 0.
       /proc/sys/vm/overcommit_memory
              This file contains the kernel virtual  memory  accounting  mode.
              Values are:
                     0: heuristic overcommit (this is the default)
                     1: always overcommit, never check
                     2: always check, never overcommit
              In  mode 0, calls of mmap(2) with MAP_NORESERVE are not checked,
              and the default check is very weak, leading to the risk of  get-
              ting  a process "OOM-killed".  Under Linux 2.4 any nonzero value
              implies mode 1.  In mode 2  (available  since  Linux  2.6),  the
              total  virtual  address  space on the system is limited to (SS +
              RAM*(r/100)), where SS is the size of the swap space, and RAM is
              the  size  of  the physical memory, and r is the contents of the
              file /proc/sys/vm/overcommit_ratio.
       /proc/sys/vm/overcommit_ratio
              See the description of /proc/sys/vm/overcommit_memory.
       /proc/sys/vm/panic_on_oom (since Linux 2.6.18)
              This enables or disables a kernel panic in an out-of-memory sit-
              uation.
              If this file is set to the value 0, the kernel's OOM-killer will
              kill some rogue process.  Usually, the  OOM-killer  is  able  to
              kill a rogue process and the system will survive.
              If  this  file  is  set to the value 1, then the kernel normally
              panics when out-of-memory happens.  However, if a process limits
              allocations  to  certain  nodes  using memory policies (mbind(2)
              MPOL_BIND) or cpusets (cpuset(7)) and those nodes  reach  memory
              exhaustion  status, one process may be killed by the OOM-killer.
              No panic occurs in this case: because other nodes' memory may be
              free,  this  means the system as a whole may not have reached an
              out-of-memory situation yet.
              If this file is set to the value 2,  the  kernel  always  panics
              when an out-of-memory condition occurs.
              The default value is 0.  1 and 2 are for failover of clustering.
              Select either according to your policy of failover.
       /proc/sys/vm/swappiness
              The value in this file controls how aggressively the kernel will
              swap memory pages.  Higher values increase aggressiveness, lower
              values decrease aggressiveness.  The default value is 60.
       /proc/sysrq-trigger (since Linux 2.4.21)
              Writing a character to this file triggers the same  SysRq  func-
              tion  as  typing  ALT-SysRq-<character>  (see the description of
              /proc/sys/kernel/sysrq).  This file is normally writable only by
              root.  For further details see the Linux kernel source file Doc-
              umentation/sysrq.txt.
       /proc/sysvipc
              Subdirectory containing  the  pseudo-files  msg,  sem  and  shm.
              These  files  list the System V Interprocess Communication (IPC)
              objects (respectively: message queues,  semaphores,  and  shared
              memory)  that  currently  exist on the system, providing similar
              information to that available via  ipcs(1).   These  files  have
              headers  and  are  formatted  (one IPC object per line) for easy
              understanding.  svipc(7)  provides  further  background  on  the
              information shown by these files.
       /proc/tty
              Subdirectory  containing the pseudo-files and subdirectories for
              tty drivers and line disciplines.
       /proc/uptime
              This file contains two numbers: the uptime of the  system  (sec-
              onds), and the amount of time spent in idle process (seconds).
       /proc/version
              This string identifies the kernel version that is currently run-
              ning.  It  includes  the  contents  of  /proc/sys/kernel/ostype,
              /proc/sys/kernel/osrelease  and  /proc/sys/kernel/version.   For
              example:
            Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994
       /proc/vmstat (since Linux 2.6)
              This file displays various virtual memory statistics.
       /proc/zoneinfo (since Linux 2.6.13)
              This file display information about memory zones.  This is  use-
              ful for analyzing virtual memory behavior.
NOTES
       Many strings (i.e., the environment and command line) are in the inter-
       nal format, with subfields terminated by null bytes ('\0'), so you  may
       find  that  things are more readable if you use od -c or tr "\000" "\n"
       to read them.  Alternatively, echo `cat <file>` works well.
       This manual page is incomplete, possibly inaccurate, and is the kind of
       thing that needs to be updated very often.
SEE ALSO
       cat(1), dmesg(1), find(1), free(1), ps(1), tr(1), uptime(1), chroot(2),
       mmap(2), readlink(2), syslog(2), slabinfo(5), hier(7), time(7), arp(8),
       hdparm(8),  ifconfig(8),  init(8),  lsmod(8),  lspci(8), mount(8), net-
       stat(8), procinfo(8), route(8), sysctl(8)
       The Linux kernel source files:  Documentation/filesystems/proc.txt  and
       Documentation/sysctl/vm.txt.
COLOPHON
       This  page  is  part of release 3.53 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

Linux                             2013-08-01                           PROC(5)