Sleep (command)

In computing, sleep is a command in Unix, Unix-like and other operating systems that suspends program execution for a specified time.

The sleep instruction suspends the calling process for at least the specified number of seconds (the default), minutes, hours or days.

sleep for Unix-like systems is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX and the Single Unix Specification. It first appeared in Version 4 Unix.

The version of sleep bundled in GNU coreutils was written by Jim Meyering and Paul Eggert. The command is also available in the OS-9 shell, in the KolibriOS Shell, and part of the FreeDOS Package group Utilities. The FreeDOS version was developed by Trane Francks and is licensed under the GPL.

A sleep command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.

In PowerShell, sleep is a predefined command alias for the Start-Sleep cmdlet which serves the same purpose. Microsoft also provides a sleep resource kit tool for Windows which can be used in batch files or the command prompt to pause the execution and wait for some time. Another native version is the timeout command which is part of current versions of Windows.

The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities. The sleep command has also been ported to the IBM i operating system.

Where number is an integer number to indicate the time period in seconds. Some implementations support floating point numbers.