.\" Copyright (c) 1986, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" From: @(#)ualarm.3 8.2 (Berkeley) 4/19/94 .\" $FreeBSD: src/lib/libc/gen/ualarm.3,v 1.19 2004/07/02 23:52:10 ru Exp $ .\" .Dd April 19, 1994 .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 .Fo ualarm .Fa "useconds_t useconds" .Fa "useconds_t interval" .Fc .Sh DESCRIPTION .Bf -symbolic This is a simplified interface to .Xr setitimer 2 . .Ef .Pp The .Fn ualarm function waits a count of .Fa useconds 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 useconds number of microseconds have passed). .Pp Due to a .Xr setitimer 2 restriction, the maximum number of .Fa useconds and .Fa interval is limited to 100,000,000,000,000 (in case this value fits in the unsigned integer). .Sh RETURN VALUES When the signal has successfully been caught, .Fn ualarm returns the amount of time left on the clock. .Sh NOTES A microsecond is 0.000001 seconds. .Sh SEE ALSO .Xr getitimer 2 , .Xr setitimer 2 , .Xr sigpause 2 , .Xr sigvec 2 , .Xr alarm 3 , .Xr signal 3 , .Xr sleep 3 , .Xr usleep 3 .Sh HISTORY The .Fn ualarm function appeared in .Bx 4.3 .