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ualarm.3

UALARM

Section: Linux Programmer's Manual (3)
Updated: 2008-08-06
Index Return to Main Contents
 

NAME

ualarm - schedule signal after given number of microseconds  

SYNOPSIS

#include <unistd.h>

useconds_t ualarm(useconds_t usecs, useconds_t interval);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

ualarm(): _BSD_SOURCE || _XOPEN_SOURCE >= 500  

DESCRIPTION

The ualarm() function causes the signal SIGALRM to be sent to the invoking process after (not less than) usecs microseconds. The delay may be lengthened slightly by any system activity or by the time spent processing the call or by the granularity of system timers.

Unless caught or ignored, the SIGALRM signal will terminate the process.

If the interval argument is non-zero, further SIGALRM signals will be sent every interval microseconds after the first.  

RETURN VALUE

This function returns the number of microseconds remaining for any alarm that was previously set, or 0 if no alarm was pending.  

ERRORS

EINTR
Interrupted by a signal.
EINVAL
usecs or interval is not smaller than 1000000. (On systems where that is considered an error.)
 

CONFORMING TO

4.3BSD, POSIX.1-2001. POSIX.1-2001 marks ualarm() as obsolete. POSIX.1-2008 removes the specification of ualarm(). 4.3BSD, SUSv2, and POSIX do not define any errors.  

NOTES

The type useconds_t is an unsigned integer type capable of holding integers in the range [0,1000000]. On the original BSD implementation, and in glibc before version 2.1, the arguments to ualarm() were instead typed as unsigned int. Programs will be more portable if they never mention useconds_t explicitly.

The interaction of this function with other timer functions such as alarm(2), sleep(3), nanosleep(2), setitimer(2), timer_create(2), timer_delete(2), timer_getoverrun(2), timer_gettime(2), timer_settime(2), usleep(3) is unspecified.

This function is obsolete. Use setitimer(2) or POSIX interval timers (timer_create(2), etc.) instead.  

SEE ALSO

alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), usleep(3), time(7)  

COLOPHON

This page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTES
SEE ALSO
COLOPHON

 

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