Originální popis anglicky:
ualarm - schedule signal after given number of microseconds
Návod, kniha: Linux Programmer's Manual
/* BSD version */
#include <unistd.h>
unsigned int
ualarm(unsigned int usecs, unsigned int interval);
/* SUSv2 version */
#define _XOPEN_SOURCE 500
#include <unistd.h>
useconds_t ualarm(useconds_t usecs, useconds_t interval);
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, this signal will terminate the process.
If the
interval argument is nonzero, further SIGALRM signals will be sent
every
interval microseconds after the first.
This function returns the number of microseconds remaining from the previous
call, or 0 when no alarm is pending.
- EINTR
- Interrupted by a signal.
- EINVAL
- usecs or interval is not smaller than
1000000. (On systems where that is considered an error.)
BSD 4.3, POSIX 1003.1-2003. BSD 4.3, SUSv2 and POSIX do not define any errors.
The type
useconds_t is an unsigned integer type capable of holding
integers in the range [0,1000000]. This type is defined by
<sys/types.h> included by
<unistd.h> but glibc
defines it only when _XOPEN_SOURCE has a value not less than 500, or both
_XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED are defined. Programs will be more
portable if they never mention this type explicitly.
The interaction of this function with other timer functions such as
alarm(),
sleep(),
nanosleep(),
setitimer(),
timer_create(),
timer_delete(),
timer_getoverrun(),
timer_gettime(),
timer_settime(),
usleep() is
unspecified.
This function is obsolete. Use
nanosleep(2) or
setitimer(2)
instead.
alarm(2),
getitimer(2),
nanosleep(2),
select(2),
setitimer(2),
usleep(3)
