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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 |
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.1‐2008, 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.1‐2008 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.1‐2008, Chapter 8, Environment
Variables
The System Interfaces volume of POSIX.1‐2008, alarm(3p), sleep(3p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 SLEEP(1P)