alarm(S)                       6 January 1993                       alarm(S)


 Name

    alarm - set a process alarm clock

 Syntax


    cc  . . .  -lc


    unsigned int alarm (seconds)
    unsigned int seconds;


 Description

    The alarm function causes the system to send the calling process a
    SIGALRM signal after the number of real time seconds has elapsed.  If
    seconds is zero (0), a pending alarm request, if any, is cancelled.  Pro-
    cessor scheduling delays may prevent the process from handling the signal
    as soon as it is generated.

    Refer to signal(S) for more information on SIGALRM.

    alarm requests are not stacked; successive calls reset the alarm clock of
    the calling process.

    The fork(S) system call sets the alarm clock of a child process to 0.  A
    process created by the exec(S) family of calls inherits the time left on
    the old process's alarm clock.

 See also

    exec(S), fork(S), getitimer(S), signal(S), sigaction(S)

 Diagnostics

    The alarm function is always successful and no return value is reserved
    to indicate an error.  This function returns the amount of time, in
    seconds, remaining before the system is scheduled to generate the SIGALRM
    signal from the previous call to alarm, or zero if there was no previous
    alarm request.

 Standards conformance

    alarm is conformant with:
    X/Open Portability Guide, Issue 3, 1989;
    IEEE POSIX Std 1003.1-1990 System Application Program Interface (API) [C
    Language] (ISO/IEC 9945-1);
    and NIST FIPS 151-1.