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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SLEEP(1P) POSIX Programmer's Manual SLEEP(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
sleep — suspend execution for an interval
sleep time
The sleep utility shall suspend execution for at least the
integral number of seconds specified by the time operand.
None.
The following operand shall be supported:
time A non-negative decimal integer specifying the number of
seconds for which to suspend execution.
Not used.
None.
The following environment variables shall affect the execution of
sleep:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of sequences
of bytes of text data as characters (for example,
single-byte as opposed to multi-byte characters in
arguments).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
If the sleep utility receives a SIGALRM signal, one of the
following actions shall be taken:
1. Terminate normally with a zero exit status.
2. Effectively ignore the signal.
3. Provide the default behavior for signals described in the
ASYNCHRONOUS EVENTS section of Section 1.4, Utility
Description Defaults. This could include terminating with a
non-zero exit status.
The sleep utility shall take the standard action for all other
signals.
Not used.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 The execution was successfully suspended for at least time
seconds, or a SIGALRM signal was received. See the
ASYNCHRONOUS EVENTS section.
>0 An error occurred.
Default.
The following sections are informative.
None.
The sleep utility can be used to execute a command after a certain
amount of time, as in:
(sleep 105; command) &
or to execute a command every so often, as in:
while true
do
command
sleep 37
done
The exit status is allowed to be zero when sleep is interrupted by
the SIGALRM signal because most implementations of this utility
rely on the arrival of that signal to notify them that the
requested finishing time has been successfully attained. Such
implementations thus do not distinguish this situation from the
successful completion case. Other implementations are allowed to
catch the signal and go back to sleep until the requested time
expires or to provide the normal signal termination procedures.
As with all other utilities that take integral operands and do not
specify subranges of allowed values, sleep is required by this
volume of POSIX.1‐2017 to deal with time requests of up to
2147483647 seconds. This may mean that some implementations have
to make multiple calls to the delay mechanism of the underlying
operating system if its argument range is less than this.
None.
wait(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables
The System Interfaces volume of POSIX.1‐2017, alarm(3p), sleep(3p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 SLEEP(1P)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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