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.\"     @(#)ualarm.3	8.2 (Berkeley) 4/19/94
.\"
.Dd May 2, 2011
.Dt UALARM 3
.Os
.Sh NAME
.Nm ualarm
.Nd schedule signal after specified time
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft useconds_t
.Fn ualarm "useconds_t microseconds" "useconds_t interval"
.Sh DESCRIPTION
.Bf -symbolic
This is a simplified interface to
.Xr setitimer 2 .
.Ef
.Pp
The
.Fn ualarm
function
waits a count of
.Ar microseconds
before asserting the terminating signal
.Dv SIGALRM .
System activity or time used in processing the call may cause a slight
delay.
.Pp
If the
.Fa interval
argument is non-zero, the
.Dv SIGALRM
signal will be sent
to the process every
.Fa interval
microseconds after the timer expires (e.g. after
.Fa microseconds
microseconds have passed).
.Sh RETURN VALUES
When the signal has successfully been caught,
.Fn ualarm
returns the amount of time left on the clock.
The maximum number of
.Ar microseconds
allowed
is 2147483647.
If there is an error setting the timer,
.Fn ualarm
returns ((useconds_t) -1).
.Sh SEE ALSO
.Xr getitimer 2 ,
.Xr setitimer 2 ,
.Xr sigaction 2 ,
.Xr sigsuspend 2 ,
.Xr alarm 3 ,
.Xr signal 3 ,
.Xr sigvec 3 ,
.Xr sleep 3 ,
.Xr usleep 3
.Sh STANDARDS
The
.Fn ualarm
function conforms to
.St -p1003.1-2001 .
However, the later
.St -p1003.1-2008
revision removed the function from the specification.
.Sh HISTORY
The
.Fn ualarm
function appeared in
.Bx 4.3 .