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@(#)usleep.3 8.1 (Berkeley) 6/4/93
.Dd April 22, 2024 .Dt USLEEP 3 .Os .Sh NAME .Nm usleep .Nd suspend execution for interval of microseconds .Sh LIBRARY .Lb libc .Sh SYNOPSIS n unistd.h .Ft int .Fn usleep "useconds_t microseconds" .Sh DESCRIPTION f -symbolic This interface is obsoleted by .Xr nanosleep 3 . .Ef
p The .Fn usleep function suspends execution of the calling process until either the number of microseconds specified by .Fa microseconds have elapsed or a signal is delivered to the calling process and its action is to invoke a signal catching function or to terminate the process. The suspension time may be longer than requested due to the scheduling of other activity by the system. .Sh RETURN VALUES On successful completion, .Fn usleep returns 0. Otherwise, it returns -1 and sets .Va errno to indicate the error. .Sh ERRORS The .Fn usleep function may fail if: l -tag -width Er t Bq Er EINTR .Nm was interrupted by the delivery of a signal. .El .Sh SEE ALSO .Xr nanosleep 2 , .Xr sleep 3 .Sh STANDARDS The .Fn usleep function conforms to .St -xpg4.2 . It later appeared in the .Tn POSIX standard, but in .St -p1003.1-2004 it was marked as legacy and the use of .Xr nanosleep 2 was recommended instead. The .St -p1003.1-2008 revision removed .Fn usleep from the specification. .Sh HISTORY The .Fn usleep function appeared in x 4.3 .