time(1)

NAME

     time - time a simple command

SYNOPSIS

     time [-p] utility [argument...]

DESCRIPTION

     The time utility invokes utility operand with argument,  and
     writes a message to standard error that lists timing statis-
     tics for utility. The message includes the following  infor-
     mation:

        o  The elapsed (real) time between invocation of  utility
           and its termination.

        o  The User CPU  time,  equivalent  to  the  sum  of  the
           tms_utime   and  tms_cutime  fields  returned  by  the
           times(2) function for the process in which utility  is
           executed.

        o  The System CPU time, equivalent  to  the  sum  of  the
           tms_stime   and  tms_cstime  fields  returned  by  the
           times() function for the process in which  utility  is
           executed.

     When time is used as part of a pipeline, the times  reported
     are unspecified, except when it is the sole command within a
     grouping command in that pipeline. For example, the commands
     on  the  left  are unspecified; those on the right report on
     utilities a and c, respectively:

     time a | b | c      { time a } | b | c
     a | b | time c      a | b | (time c)

OPTIONS

     The following option is supported:

     -p    Writes the timing output to standard error in the fol-
           lowing format:

           real %f\nuser %f\nsys %f\n < real seconds>, <user seconds>,
           <system seconds>

OPERANDS

     The following operands are supported:

     utility
           The name of the utility that is to be invoked.

     argument
           Any string to be supplied as an argument when invoking
           utility.

USAGE

     The time utility returns exit status 127 if an error  occurs
     so  that  applications  can  distinguish  "failure to find a
     utility" from "invoked utility exited with an error  indica-
     tion."  The  value 127 was chosen because it is not commonly
     used for other meanings. Most utilities use small values for
     "normal  error  conditions"  and the values above 128 can be
     confused with termination due to receipt of  a  signal.  The
     value  126  was  chosen in a similar manner to indicate that
     the utility could be found, but not invoked.

EXAMPLES

     Example 1: Using the time command

     It is frequently desirable to apply  time  to  pipelines  or
     lists of commands. This can be done by placing pipelines and
     command lists in a single file. This single file can then be
     invoked  as a utility, and the time applies to everything in
     the file.

     Alternatively, the following command can be  used  to  apply
     time to a complex command:

     example% time sh -c 'complex-command-line'

     Example 2: Using time in the csh shell

     The following two examples show the differences between  the
     csh  version of time and the version in /usr/bin/time. These
     examples assume that csh is the shell in use.

     example% time find / -name csh.1 -print
     /usr/share/man/man1/csh.1
     95.0u 692.0s 1:17:52 16% 0+0k 0+0io 0pf+0w

     See csh(1) for an explanation of the format of time output.

     example% /usr/bin/time find / -name csh.1 -print
     /usr/share/man/man1/csh.1
     real  1:23:31.5
     user     1:33.2
     sys     11:28.2

ENVIRONMENT VARIABLES

     See environ(5) for descriptions of the following environment
     variables  that  affect the execution of time: LANG, LC_ALL,
     LC_CTYPE, LC_MESSAGES, LC_NUMERIC,  NLSPATH, and PATH.

EXIT STATUS

     If utility is invoked, the exit status of time will  be  the
     exit  status  of  utility.  Otherwise, the time utility will
     exit with one of the following values:

     1-125 An error occurred in the time utility.

     126   utility was found but could not be invoked.

     127   utility could not be found.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|
    | Interface Stability         | Standard                    |
    |_____________________________|_____________________________|

SEE ALSO

     csh(1),  shell_builtins(1),   timex(1),   times(2),   attri-
     butes(5), environ( 5), standards(5)

NOTES

     When the time command is run on  a  multiprocessor  machine,
     the  total of the values printed for user and sys can exceed
     real. This is  because on a  multiprocessor  machine  it  is
     possible to divide the task between the various processors.

     When the command being  timed  is  interrupted,  the  timing
     values displayed may not always be accurate.

BUGS

     Elapsed time is accurate to the second, while the CPU  times
     are  measured  to  the 100th second. Thus the sum of the CPU
     times can be up to a second larger than the elapsed time.