ualarm(3) Library Functions Manual ualarm(3) ualarm - C (libc, -lc) #include useconds_t ualarm(useconds_t usecs, useconds_t interval); glibc (. feature_test_macros(7)): ualarm(): glibc 2.12: (_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L) || /* glibc >= 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE glibc 2.12: _BSD_SOURCE || _XOPEN_SOURCE >= 500 ualarm() SIGALRM ( ) usecs . , -, , - . , SIGALRM . interval , SIGALRM interval . , , 0, . EINTR ; . signal(7). EINVAL usecs or interval is not smaller than 1000000. (On systems where that is considered an error.) attributes(7). +----------------------------+----------------------------------------------------------+--------------------------+ | | | | +----------------------------+----------------------------------------------------------+--------------------------+ |ualarm() | | MT-Safe | +----------------------------+----------------------------------------------------------+--------------------------+ . 4.3BSD, POSIX.1-2001. POSIX.1-2001 marks it as obsolete. Removed in POSIX.1-2008. 4.3BSD, SUSv2, and POSIX do not define any errors. POSIX.1-2001 , , usecs 0. Linux (, , ) . 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 glibc 2.1, the arguments to ualarm() were instead typed as unsigned int. Programs will be more portable if they never mention useconds_t explicitly. , 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) . . setitimer(2) POSIX (timer_create(2) ..). alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), usleep(3), time(7) () Azamat Hackimov , Dmitriy Ovchinnikov , Dmitry Bolkhovskikh , Katrin Kutepova , Yuri Kozlov ; GNU (GNU General Public License - GPL, 3 ) , - . - , , () () () . Linux man-pages 6.18 8 2026 . ualarm(3)