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| | time - time a simple command |
SYNOPSIS
| | time [-p] utility [ argument. ..] |
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The time utility invokes utility operand with argument, and writes a message to standard error that lists timing statistics
for utility. The message includes the following information:
- The elapsed (real) time between invocation of utility and its termination.
- 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.
- 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.
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time a | b | c { time a } | b | c
a | b | time c a | b | (time c)
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The following option is supported:
- -p
- Write the timing output to standard error in the following format:
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real %f\nuser %f\nsys %f\n < real seconds>, <user seconds>,
<system seconds>
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The following operands are supported:
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utility
- The name of the utility that is to be invoked.
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argument
- Any string to be supplied as an argument when invoking utility.
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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 indication." 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.
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| | Example 1. Using The time Coommand
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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 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:
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time sh -c 'complex-command-line'
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Example 2. Using time In The csh Shell
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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.
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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
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See csh(1) for an explanation of the format
of time output.
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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
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See environ(5) for descriptions of the following environment
variables that affect the execution of time: LC_CTYPE, LC_MESSAGES,
LC_NUMERIC, NLSPATH, and PATH.
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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:
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1-125
- An error occurred in the time utility.
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126
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utility was found but could not be invoked.
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127
-
utility could not be found.
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See attributes(5) for descriptions of the following
attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
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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.
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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.
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