Objective: Track the amount of time a command takes on Unix / Linux.
The time command can be used to track the amount of time taken for a command to run.
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$ time /path/to/command real 0m2.005s user 0m0.000s sys 0m0.000s |
The above output indicates that the command took slightly more than 2 seconds to execute. The real time is the elapsed “wall clock” time. It is like using a stop watch to monitor the process start and stop time.
There are 2 variants of the time command. The first is the standalone external time command normally installed in /usr/bin. The other is a shell keyword or builtin command. To check if you are using the shell keyword / builtin or the external time binary, use the type command.
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$ type time time is a shell keyword |
The about output means that the time command is a shell keyword, and the command will be executed by the shell. So, by default, the shell will not execute the external time command found in /usr/bin. On some shells, type command (eg. tcsh) will not work. Use which command instead on such shells.
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$ which time time: shell built-in command. |
To force the shell to use the external time command, use one of the two syntaxes below. Not all shells will support both syntaxes.
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$ command time /path/to/command |
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$ \time /path/to/command |
To get the elapsed real (wall clock) time used by a process in seconds, use the following syntax.
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$ \time -f "%e" sleep 2 2.00 |
The above output shows that the “sleep 2” command took 2 seconds to execute, which is correct based on the argument “2” that was passed to the sleep command.
Mohamed Ibrahim
ibrahim = { interested_in(unix, linux, android, open_source, reverse_engineering); coding(c, shell, php, python, java, javascript, nodejs, react); plays_on(xbox, ps4); linux_desktop_user(true); }
