sleep(1p) — Linux manual page

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.1‐2017, 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.

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.1‐2017 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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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)