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Info Node: (time.info)Resource Measurement

(time.info)Resource Measurement


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Measuring Program Resource Use
******************************

   The `time' command runs another program, then displays information
about the resources used by that program, collected by the system while
the program was running.  You can select which information is reported
and the format in which it is shown (Note: Setting Format), or have
`time' save the information in a file instead of displaying it on the
screen (Note: Redirecting).

   The resources that `time' can report on fall into the general
categories of time, memory, and I/O and IPC calls.  Some systems do not
provide much information about program resource use; `time' reports
unavailable information as zero values (Note: Accuracy).

   The format of the `time' command is:

     time [option...] COMMAND [ARG...]

   `time' runs the program COMMAND, with any given arguments ARG....
When COMMAND finishes, `time' displays information about resources used
by COMMAND.

   Here is an example of using `time' to measure the time and other
resources used by running the program `grep':

     eg$ time grep nobody /etc/aliases
     nobody:/dev/null
     etc-files:nobody
     misc-group:nobody
     0.07user 0.50system 0:06.69elapsed 8%CPU (0avgtext+489avgdata 324maxresident)k
     46inputs+7outputs (43major+251minor)pagefaults 0swaps

   Mail suggestions and bug reports for GNU `time' to
`bug-gnu-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.

Setting Format
Selecting the information reported by `time'.
Format String
The information `time' can report.
Redirecting
Writing the information to a file.
Examples
Examples of using `time'.
Accuracy
Limitations on the accuracy of `time' output.
Invoking time
Summary of the options to the `time' command.

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