huschi.net

TIME(1)                       Linux User's Manual                      TIME(1)

NAME
       time - time a simple command or give resource usage
SYNOPSIS
       time [options] command [arguments...]
DESCRIPTION
       The  time  command  runs  the  specified program command with the given
       arguments.  When command finishes, time writes a  message  to  standard
       error  giving  timing statistics about this program run.  These statis-
       tics consist of (i) the elapsed real time between invocation and termi-
       nation, (ii) the user CPU time (the sum of the tms_utime and tms_cutime
       values in a struct tms as returned by times(2)), and (iii)  the  system
       CPU  time  (the  sum of the tms_stime and tms_cstime values in a struct
       tms as returned by times(2)).
       Note: some shells (e.g., bash(1)) have a  built-in  time  command  that
       provides less functionality than the command described here.  To access
       the real command, you may need to specify its pathname (something  like
       /usr/bin/time).
OPTIONS
       -p     When in the POSIX locale, use the precise traditional format
                  "real %f\nuser %f\nsys %f\n"
              (with  numbers  in  seconds) where the number of decimals in the
              output for %f is unspecified but is sufficient  to  express  the
              clock tick accuracy, and at least one.
EXIT STATUS
       If  command was invoked, the exit status is that of command.  Otherwise
       it is 127 if command could not be found, 126 if it could be  found  but
       could not be invoked, and some other nonzero value (1-125) if something
       else went wrong.
ENVIRONMENT
       The variables LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, LC_NUMERIC, NLSPATH,
       and  PATH are used.  The last one to search for command.  The remaining
       ones for the text and formatting of the output.
GNU VERSION
       Below a description of the GNU 1.7 version of time.   Disregarding  the
       name  of  the  utility, GNU makes it output lots of useful information,
       not only about time used, but also on other resources like memory,  I/O
       and  IPC calls (where available).  The output is formatted using a for-
       mat string that can be specified using the -f option or the TIME  envi-
       ronment variable.
       The default format string is:
           %Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
           %Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps
       When the -p option is given the (portable) output format
           real %e
           user %U
           sys %S
       is used.
   The format string
       The format is interpreted in the usual printf-like way.  Ordinary char-
       acters are directly copied, tab,  newline  and  backslash  are  escaped
       using \t, \n and \\, a percent sign is represented by %%, and otherwise
       % indicates a conversion.  The program time will always add a  trailing
       newline  itself.  The conversions follow.  All of those used by tcsh(1)
       are supported.
       Time
       %E     Elapsed real time (in [hours:]minutes:seconds).
       %e     (Not in tcsh.) Elapsed real time (in seconds).
       %S     Total number of CPU-seconds that the  process  spent  in  kernel
              mode.
       %U     Total number of CPU-seconds that the process spent in user mode.
       %P     Percentage of the CPU that this job got, computed as (%U + %S) /
              %E.
       Memory
       %M     Maximum resident set size of the process during its lifetime, in
              Kbytes.
       %t     (Not  in  tcsh.)  Average  resident  set size of the process, in
              Kbytes.
       %K     Average total (data+stack+text) memory use of  the  process,  in
              Kbytes.
       %D     Average size of the process's unshared data area, in Kbytes.
       %p     (Not  in  tcsh.)  Average  size  of the process's unshared stack
              space, in Kbytes.
       %X     Average size of the process's shared text space, in Kbytes.
       %Z     (Not in tcsh.) System's page size, in bytes.  This is a per-sys-
              tem constant, but varies between systems.
       %F     Number  of major page faults that occurred while the process was
              running.  These are faults where the page has to be read in from
              disk.
       %R     Number  of minor, or recoverable, page faults.  These are faults
              for pages that are not valid but which have not yet been claimed
              by  other  virtual  pages.   Thus  the data in the page is still
              valid but the system tables must be updated.
       %W     Number of times the process was swapped out of main memory.
       %c     Number of times the process was  context-switched  involuntarily
              (because the time slice expired).
       %w     Number  of  waits:  times  that the program was context-switched
              voluntarily, for instance while waiting for an I/O operation  to
              complete.
       I/O
       %I     Number of file system inputs by the process.
       %O     Number of file system outputs by the process.
       %r     Number of socket messages received by the process.
       %s     Number of socket messages sent by the process.
       %k     Number of signals delivered to the process.
       %C     (Not  in  tcsh.)  Name and command-line arguments of the command
              being timed.
       %x     (Not in tcsh.) Exit status of the command.
   GNU options
       -f FORMAT, --format=FORMAT
              Specify output format, possibly overriding the format  specified
              in the environment variable TIME.
       -p, --portability
              Use the portable output format.
       -o FILE, --output=FILE
              Do  not  send the results to stderr, but overwrite the specified
              file.
       -a, --append
              (Used together with -o.) Do not overwrite but append.
       -v, --verbose
              Give very verbose output about all the program knows about.
   GNU standard options
       --help Print a usage message on standard output and exit successfully.
       -V, --version
              Print version information on standard output, then exit success-
              fully.
       --     Terminate option list.
BUGS
       Not  all resources are measured by all versions of UNIX, so some of the
       values might be reported as zero.  The  present  selection  was  mostly
       inspired by the data provided by 4.2 or 4.3BSD.
       GNU time version 1.7 is not yet localized.  Thus, it does not implement
       the POSIX requirements.
       The environment variable TIME was badly chosen.  It is not unusual  for
       systems  like  autoconf(1) or make(1) to use environment variables with
       the name of a utility to override the utility to be  used.   Uses  like
       MORE  or  TIME  for  options to programs (instead of program pathnames)
       tend to lead to difficulties.
       It seems unfortunate that -o overwrites instead of appends.  (That  is,
       the -a option should be the default.)
       Mail suggestions and bug reports for GNU time to
       bug-utils AT prep.edu
       Please include the version of time, which you can get by running
       time --version
       and the operating system and C compiler you used.
SEE ALSO
       tcsh(1), times(2), wait3(2)
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/.

                                  2008-11-14                           TIME(1)