Time (Unix)

This article is about a Unix command. If you are looking for Unix s means of representing points in time, see Unix time.

time is a command in the Unix operating systems. It is used to determine the duration of execution of a particular command. To use the command, simply precede any command by the word time, such as:

:time ls

When the command completes, time will report how long it took to execute in terms of user CPU time, system CPU time, and real time. The output format varies between different versions of the command, and some give additional statistics, as in this example:

$ time host wikipedia.org wikipedia.org has address 207.142.131.235 0.000u 0.000s 0:00.17 0.0% 0+0k 0+0io 0pf+0w $

time(1) can exist as a standalone program (such as GNU time) or as a Unix shell builtin (e.g. in Tcsh or in zsh).