df(1p) - phpMan

DF(1P)                     POSIX Programmer's Manual                    DF(1P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       df - report free disk space
SYNOPSIS
       df [-k][-P|-t][file...]
DESCRIPTION
       The df utility shall write the amount  of  available  space   and  file
       slots  for file systems on which the invoking user has appropriate read
       access. File systems shall be specified by the file operands; when none
       are  specified,  information shall be written for all file systems. The
       format of the default output from df is unspecified, but all space fig-
       ures are reported in 512-byte units, unless the -k option is specified.
       This output shall contain at least the file  system  names,  amount  of
       available  space on each of these file systems,  and the number of free
       file slots, or inodes, available; when  -t  is  specified,  the  output
       shall contain the total allocated space as well.
OPTIONS
       The  df  utility  shall  conform  to  the  Base  Definitions  volume of
       IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines.
       The following options shall be supported:
       -k     Use 1024-byte units, instead of the default 512-byte units, when
              writing space figures.
       -P     Produce output in the format described in the STDOUT section.
       -t     Include total allocated-space figures in the output.

OPERANDS
       The following operand shall be supported:
       file   A  pathname  of  a file within the hierarchy of the desired file
              system.  If a file other than a FIFO, a regular file,  a  direc-
              tory,   or a special file representing the device containing the
              file system  (for  example,  /dev/dsk/0s1)   is  specified,  the
              results  are  unspecified.  Otherwise, df shall write the amount
              of free space in the file system containing the  specified  file
              operand.

STDIN
       Not used.
INPUT FILES
       None.
ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of df:
       LANG   Provide  a  default value for the internationalization variables
              that are unset or null. (See  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001,  Section  8.2,  Internationalization Vari-
              ables for the precedence of internationalization variables  used
              to determine the values of locale categories.)
       LC_ALL If  set  to a non-empty string value, override the values of all
              the other internationalization variables.
       LC_CTYPE
              Determine the locale for  the  interpretation  of  sequences  of
              bytes  of  text  data as characters (for example, single-byte as
              opposed to multi-byte characters in arguments).
       LC_MESSAGES
              Determine the locale that should be used to  affect  the  format
              and  contents  of  diagnostic messages written to standard error
              and informative messages written to standard output.
       NLSPATH
              Determine the location of message catalogs for the processing of
              LC_MESSAGES .

ASYNCHRONOUS EVENTS
       Default.
STDOUT
       When  both  the  -k  and -P options are specified, the following header
       line shall be written (in the POSIX locale):

              "Filesystem 1024-blocks Used Available Capacity Mounted on\n"
       When the -P option is specified without the -k  option,  the  following
       header line shall be written (in the POSIX locale):

              "Filesystem 512-blocks Used Available Capacity Mounted on\n"
       The  implementation  may  adjust the spacing of the header line and the
       individual data lines so that the information is presented  in  orderly
       columns.
       The  remaining  output with -P shall consist of one line of information
       for each specified file system. These lines shall be formatted as  fol-
       lows:

              "%s %d %d %d %d%% %s\n", <file system name>, <total space>,
                  <space used>, <space free>, <percentage used>,
                  <file system root>
       In  the  following  list,  all  quantities  expressed in 512-byte units
       (1024-byte when -k is specified) shall be rounded up to the next higher
       unit. The fields are:
       <file system name>
              The  name  of the file system, in an implementation-defined for-
              mat.
       <total space>
              The total size of the file system in 512-byte units.  The  exact
              meaning  of  this  figure  is implementation-defined, but should
              include <space used>, <space free>, plus any space  reserved  by
              the system not normally available to a user.
       <space used>
              The  total  amount  of  space allocated to existing files in the
              file system, in 512-byte units.
       <space free>
              The total amount of space available within the file  system  for
              the  creation  of  new  files by unprivileged users, in 512-byte
              units. When this figure is less than or equal to zero, it  shall
              not be possible to create any new files on the file system with-
              out first deleting others, unless the  process  has  appropriate
              privileges.  The figure written may be less than zero.
       <percentage used>
              The percentage of the normally available space that is currently
              allocated to all files on the file system. This shall be  calcu-
              lated using the fraction:

              <space used>/( <space used>+ <space free>)
       expressed  as  a percentage. This percentage may be greater than 100 if
       <space free> is less than zero. The percentage value shall be expressed
       as  a  positive  integer,  with  any fractional result causing it to be
       rounded to the next highest integer.
       <file system root>
              The directory below which the file system hierarchy appears.

       The output format is unspecified when -t is used.
STDERR
       The standard error shall be used only for diagnostic messages.
OUTPUT FILES
       None.
EXTENDED DESCRIPTION
       None.
EXIT STATUS
       The following exit values shall be returned:
        0     Successful completion.
       >0     An error occurred.

CONSEQUENCES OF ERRORS
       Default.
       The following sections are informative.
APPLICATION USAGE
       On most systems, the "name of the file system,  in  an  implementation-
       defined  format"  is  the  special  file  on  which  the file system is
       mounted.
       On large file systems, the calculation specified  for  percentage  used
       can create huge rounding errors.
EXAMPLES
        1. The  following  example  writes portable information about the /usr
           file system:

           df -P /usr
        2. Assuming that /usr/src is part of the /usr file system, the follow-
           ing produces the same output as the previous example:

           df -P /usr/src
RATIONALE
       The  behavior of df with the -P option is the default action of the 4.2
       BSD df utility. The uppercase -P was selected to avoid collision with a
       known industry extension using -p.
       Historical  df  implementations vary considerably in their default out-
       put. It was therefore necessary to describe the  default  output  in  a
       loose manner to accommodate all known historical implementations and to
       add a portable option ( -P) to provide information in a  portable  for-
       mat.
       The use of 512-byte units is historical practice and maintains compati-
       bility   with   ls   and   other   utilities   in   this   volume    of
       IEEE Std 1003.1-2001. This does not mandate that the file system itself
       be based on 512-byte blocks. The -k option was added  as  a  compromise
       measure.   It  was agreed by the standard developers that 512 bytes was
       the best default unit because of its complete historical consistency on
       System  V  (versus  the  mixed 512/1024-byte usage on BSD systems), and
       that a -k option to switch to 1024-byte units was  a  good  compromise.
       Users  who  prefer the more logical 1024-byte quantity can easily alias
       df to df -k without breaking many historical  scripts  relying  on  the
       512-byte units.
       It  was suggested that df and the various related utilities be modified
       to access a BLOCKSIZE environment variable to achieve  consistency  and
       user  acceptance.  Since this is not historical practice on any system,
       it is left as a possible area for system extensions  and  will  be  re-
       evaluated in a future version if it is widely implemented.
FUTURE DIRECTIONS
       None.
SEE ALSO
       find
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                               DF(1P)