


      SLEEP(3C)                   (UNIX 5.0)                  SLEEP(3C)



      NAME
           sleep - suspend execution for interval

      SYNOPSIS
           unsigned sleep (seconds)
           unsigned seconds;

      DESCRIPTION
           The current process is suspended from execution for the
           number of seconds specified by the argument.  The actual
           suspension time may be less than that requested for two
           reasons: (1) Because scheduled wakeups occur at fixed 1-
           second intervals, (on the second, according to an internal
           clock) and (2) because any caught signal will terminate the
           sleep following execution of that signal's catching routine.
           Also, the suspension time may be longer than requested by an
           arbitrary amount due to the scheduling of other activity in
           the system.  The value returned by sleep will be the
           ``unslept'' amount (the requested time minus the time
           actually slept) in case the caller had an alarm set to go
           off earlier than the end of the requested sleep time, or
           premature arousal due to another caught signal.

           The routine is implemented by setting an alarm signal and
           pausing until it (or some other signal) occurs.  The
           previous state of the alarm signal is saved and restored.
           The calling program may have set up an alarm signal before
           calling sleep; if the sleep time exceeds the time till such
           alarm signal, the process sleeps only until the alarm signal
           would have occurred, and the caller's alarm catch routine is
           executed just before the sleep routine returns, but if the
           sleep time is less than the time till such alarm, the prior
           alarm time is reset to go off at the same time it would have
           without the intervening sleep.

      SEE ALSO
           alarm(2), pause(2), signal(2).


















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