SLEEP(1)                    General Commands Manual                   SLEEP(1)

NAME
     sleep – suspend execution for an interval of time

SYNOPSIS
     sleep number[unit] [...]

DESCRIPTION
     The sleep command suspends execution for a minimum of number seconds (the
     default, or unit s), minutes (unit m), hours (unit h), or days (unit d).
     Intervals can be written in any form allowed by strtod(3).  If multiple
     intervals are given, they are added together.  If the final sum is zero
     or negative, sleep exits immediately.

     If the sleep command receives a signal, it takes the standard action.
     When the SIGINFO signal is received, the estimate of the amount of
     seconds left to sleep is printed on the standard output.

IMPLEMENTATION NOTES
     The SIGALRM signal is not handled specially by this implementation.

EXIT STATUS
     The sleep utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     To run a command after half an hour:

           (sleep 0.5h; sh command_file >out 2>err)&

     This incantation would wait half an hour before running the script
     command_file.  See the at(1) utility for another way to do this.

     To reiteratively run a command:

           while :; do
                   if ! [ -r zzz.rawdata ] ; then
                           sleep 5m
                   else
                           for i in *.rawdata ; do
                                   sleep 70
                                   awk -f collapse_data "$i"
                           done >results
                           break
                   fi
           done

     The scenario for a script such as this might be: a program currently
     running is taking longer than expected to process a series of files, and
     it would be nice to have another program start processing the files
     created by the first program as soon as it is finished (when zzz.rawdata
     is created).  The script checks every five minutes for the file
     zzz.rawdata, when the file is found, then another portion processing is
     done courteously by sleeping for 70 seconds in between each awk(1) job.

SEE ALSO
     nanosleep(2), sleep(3)

STANDARDS
     The sleep command is expected to be IEEE Std 1003.2 (“POSIX.2”)
     compatible.

     Support for non-integer intervals, units other than seconds, and multiple
     intervals which are added together are non-portable extensions first
     introduced in GNU sh-utils 2.0a (released in 2002).

HISTORY
     A sleep command appeared in Version 4 AT&T UNIX.

macOS 15.2                      March 22, 2024                      macOS 15.2