TIME(1)                                                                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
       output  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)).

OPTION
       -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.

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.

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.

SEE ALSO
       times(2),



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 or make 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 path  names)  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@prep.ai.mit.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)

AUTHORS
       David Keppel
              Original version

       David MacKenzie
              POSIXization, autoconfiscation, GNU getoptization,  docu-
              mentation, other bug fixes and improvements.

       Arne Henrik Juul
              Helped with portability

       Francois Pinard
              Helped with portability



                                  2000-12-11                           TIME(1)