NAME

       sleepenh - an enhanced sleep program

SYNOPSIS

       sleepenh [[--warp|-w] INITIALTIME] TIMETOSLEEP

DESCRIPTION

       sleepenh  is  a  program  that  can be used when there is a need to execute some functions
       periodically in a shell script. It was not designed to be accurate for a single sleep, but
       to be accurate in a sequence of consecutive sleeps.
       After a successful execution, it returns to stdout the timestamp it finished running, that
       can be used as INITIALTIME to a successive execution of sleepenh.

OPTIONS

       -h, --help
              display this help and exit

       -w, --warp
              warp resulting timestamp, when there is no need to sleep.  An immediatly  following
              call  of sleepenh with the resulting TIMESTAMP would most probably result in a real
              sleep.

       -V, --version
              output version information and exit

ARGUMENTS

       TIMETOSLEEP is a real number in  seconds,  with  microseconds  resolution  (1  minute,  20
       seconds and 123456 microseconds would be 80.123456).
       INITIALTIME  is  a  real  number  in seconds, with microseconds resolution. This number is
       system dependent. In GNU/Linux systems,  it  is  the  number  of  seconds  since  midnight
       1970-01-01 GMT. Do not try to get a good value of INITIALTIME. Use the value supplied by a
       previous execution of sleepenh.
       If you don't specify INITIALTIME, it is assumed the current time.

EXIT STATUS

       An exit status greater or equal to 10 means failure.  Known exit status:

       0      Success.

       1      Success. There was no need to sleep. (means  that  INITIALTIME  +  TIMETOSLEEP  was
              greater than current time).

       10     Failure. Missing command line arguments.

       11     Failure. Did not receive SIGALRM.

       12     Failure. Argument is not a number.

       13     Failure. System error, could not get current time.

USAGE EXAMPLE

       Suppose  you need to send the char 'A' to the serial port ttyS0 every 4 seconds. This will
       do that:
               #!/bin/sh
               TIMESTAMP=`sleepenh 0`
               while true; do
                 # send the byte to ttyS0
                 echo -n "A" > /dev/ttyS0;

                 # just print a nice message on screen
                 echo -n "I sent 'A' to ttyS0, time now is ";
                 sleepenh 0;

                 # wait the required time
                 TIMESTAMP=`sleepenh $TIMESTAMP 4.0`;
               done

HINT

       This program can be used to get the current time. Just execute:

       sleepenh 0

BUGS

       It is not accurate for a single sleep. Short TIMETOSLEEPs will also not be accurate.

SEE ALSO

       date(1), sleep(1).

AUTHOR

       This manual page was written by Pedro Zorzenon Neto.