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.Dd March 22, 2024 .Dt SLEEP 1 .Os .Sh NAME .Nm sleep .Nd suspend execution for an interval of time .Sh SYNOPSIS .Nm .Ar number Ns Op Ar unit .Op ... .Sh DESCRIPTION The .Nm command suspends execution for a minimum of .Ar number seconds (the default, or unit .Li s ) , minutes (unit .Li m ) , hours (unit .Li h ) , or days (unit .Li d ) . Intervals can be written in any form allowed by .Xr strtod 3 . If multiple intervals are given, they are added together. If the final sum is zero or negative, .Nm exits immediately.
p If the .Nm command receives a signal, it takes the standard action. When the .Dv SIGINFO signal is received, the estimate of the amount of seconds left to sleep is printed on the standard output. .Sh IMPLEMENTATION NOTES The .Dv SIGALRM signal is not handled specially by this implementation. .Sh EXIT STATUS .Ex -std .Sh EXAMPLES To run a command after half an hour:
p .Dl (sleep 0.5h; sh command_file >out 2>err)&
p This incantation would wait half an hour before running the script
a command_file . See the .Xr at 1 utility for another way to do this.
p To reiteratively run a command:
p d -literal -offset indent -compact 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 .Ed
p 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
a zzz.rawdata is created). The script checks every five minutes for the file
a zzz.rawdata , when the file is found, then another portion processing is done courteously by sleeping for 70 seconds in between each .Xr awk 1 job. .Sh SEE ALSO .Xr nanosleep 2 , .Xr sleep 3 .Sh STANDARDS The .Nm command is expected to be .St -p1003.2 compatible.
p 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). .Sh HISTORY A .Nm command appeared in .At v4 .