ualarm (3)
NAME
ualarm - schedule signal after given number of microsecondsSYNOPSIS
#include <unistd.h>
useconds_t ualarm(useconds_t usecs, useconds_t interval);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
ualarm():
- Since glibc 2.12:
-
(_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L) || /* Glibc since 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE
-
Before glibc 2.12: -
_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 nonzero, 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; see signal(7).
- EINVAL
- usecs or interval is not smaller than 1000000. (On systems where that is considered an error.)
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).Interface | Attribute | Value |
ualarm () | Thread safety | MT-Safe |