In this post, you will understand the tools provided by the Linux system to calculate the time it takes for a script or command to complete execution.
It is no doubt that time is the most important resource we have. As a sys admin, you will constantly monitor your script and command time usage more times not.
Especially when configuring multiple devices, determining how long a script or command takes to complete can allow you to determine when is the right to perform maintenance, etc.
Get your cup of coffee ready and let's jump in.
time command in Linux and other Unix systems provides us with the ability to monitor how long a command takes.
time command is built-in all major shells and available in almost all Linux devices. The command follows a syntax as shown below:
time [-al] [-h | -p] [-o file] utility [argument ...]
The command accepts the following options:
-a If the -o flag is used, append to the specified file rather than overwriting it. Otherwise, this option has no effect. -h Print times in a human friendly format. Times are printed in minutes, hours, etc. as appropriate. -l The contents of the rusage structure are printed as well. -o file Write the output to file instead of stderr. If file exists and the -a flag is not specified, the file will be overwritten. -p Makes time output POSIX.2 compliant (each time is printed on its own line).
Example 1 -
time command without parameters
If we run the
time command without any arguments, the command will time details when the command run. These includes statistics such as the elapsed real time between invocation and termination, elaspsed user CPU time, system CPU time, etc.
shell 0.02s user 0.05s system 0% cpu 6:18.79 total children 0.61s user 0.32s system 0% cpu 6:18.79 total
Example 2 - Time the
The example below shows how to use the
time command to determine how long it takes to list files and directories in the
time ls -la /var/log
The command should show the file listing followed by the elapsed duration stats. A sample output is as shown:
ls -la /var/log 0.00s user 0.01s system 65% cpu 0.019 total
Keep in mind that the elapsed time is calculated in CPU seconds and not human seconds.
timecommand provided by your built-in shell or the GNU time command.
In this tutorial, we explored how to time how long a command or a script takes to finish execution using the
time command. You can check the man pages with the command
man time to discover further.
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