Suspends the execution of the current process (or thread in a
    threaded program) for at least the number of seconds indicated by
    its argument.

    Format

      #include  <unistd.h>

      unsigned int sleep  (unsigned seconds); (_DECC_V4_SOURCE)

      int sleep  (unsigned seconds); (not _DECC_V4_SOURCE)

1 - Argument

 seconds

    The number of seconds.

2 - Description

    The sleep function sleeps for the specified number of seconds, or
    until a signal is received, or until the process (or thread in a
    threaded program) executes a call to SYS$WAKE.

    If a SIGALRM signal is generated, but blocked or ignored, the
    sleep function returns. For all other signals, a blocked or
    ignored signal does not cause sleep to return.

3 - Return Values

    x                  The number of seconds that the process awoke
                       early.
    0                  If the process slept the full number of
                       seconds specified by seconds.