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)

PROLOG         top

       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.

NAME         top

       sleep — suspend execution for an interval

SYNOPSIS         top

       sleep time

DESCRIPTION         top

       The sleep utility shall suspend execution for at least the integral
       number of seconds specified by the time operand.

OPTIONS         top

       None.

OPERANDS         top

       The following operand shall be supported:

       time      A non-negative decimal integer specifying the number of
                 seconds for which to suspend execution.

STDIN         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.

ASYNCHRONOUS EVENTS         top

       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.

STDOUT         top

       Not used.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       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.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       None.

EXAMPLES         top

       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

RATIONALE         top

       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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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)