1alarm(2)                         System Calls                         alarm(2)
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NAME

6       alarm - schedule an alarm signal
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SYNOPSIS

9       #include <unistd.h>
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11       unsigned int alarm(unsigned int seconds);
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DESCRIPTION

15       The alarm() function causes the system to generate a SIGALRM signal for
16       the process after the number of real-time seconds specified by  seconds
17       have   elapsed  (see  signal.h(3HEAD)). Processor scheduling delays may
18       prevent the process from handling the signal as soon as  it  is  gener‐
19       ated.
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22       If seconds is 0, a pending alarm request, if any, is cancelled. If sec‐
23       onds  is  greater  than  LONG_MAX/hz,  seconds  is  rounded   down   to
24       LONG_MAX/hz. The value of hz is normally 100.
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27       Alarm  requests  are  not stacked; only one SIGALRM  generation can  be
28       scheduled in this manner; if the SIGALRM signal has not yet been gener‐
29       ated,  the  call  will  result  in  rescheduling  the time at which the
30       SIGALRM signal will be generated.
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33       The fork(2) function clears pending alarms in the child process. A  new
34       process image created by one of the exec(2) functions inherits the time
35       left to an alarm signal in the old process's image.
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RETURN VALUES

38       If there is a previous alarm  request  with  time   remaining,  alarm()
39       returns   a   non-zero  value  that  is the number of seconds until the
40       previous request would  have  generated  a SIGALRM signal.   Otherwise,
41       alarm() returns 0.
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ERRORS

44       The  alarm() function is always successful; no return value is reserved
45       to indicate an error.
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ATTRIBUTES

48       See attributes(5) for descriptions of the following attributes:
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53       ┌─────────────────────────────┬─────────────────────────────┐
54       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
55       ├─────────────────────────────┼─────────────────────────────┤
56       │Interface Stability          │Standard                     │
57       ├─────────────────────────────┼─────────────────────────────┤
58       │MT-Level                     │Async-Signal-Safe            │
59       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

62       exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5)
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66SunOS 5.11                        6 Jun 2007                          alarm(2)
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