sleepenh(1) [debian man page]

SLEEPENH(1)						      General Commands Manual						       SLEEPENH(1)

NAME

       sleepenh - an enhanced sleep program.

SYNOPSIS

       sleepenh [initial-time] sleep-time

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 initial-time to a successive exe-
       cution of sleepenh.

OPTIONS

       There are no command line options. Run it without any option to get a brief help and version.

ARGUMENTS

       sleep-time is a real number in seconds, with microseconds resolution (1 minute, 20 seconds and 123456 microseconds would be 80.123456).
       initial-time  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 initial-time. Use the value supplied by a previous  exe-
       cution of sleepenh.
       If you don't specify initial-time, 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 initial-time + sleep-time 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 sleep-times will also not be accurate.

SEE ALSO

       date(1), sleep(1).

AUTHOR

       This manual page was written by Pedro Zorzenon Neto.

								    2008/04/20							       SLEEPENH(1)

Check Out this Related Man Page

SLEEP(1)						    BSD General Commands Manual 						  SLEEP(1)

NAME

     sleep -- suspend execution for an interval of time

SYNOPSIS

     sleep seconds

DESCRIPTION

     The sleep command suspends execution for a minimum of seconds.

     If the sleep command receives a signal, it takes the standard action.

IMPLEMENTATION NOTES

     The SIGALRM signal is not handled specially by this implementation.

     The sleep command will accept and honor a non-integer number of specified seconds (with a '.' character as a decimal point).  This is a non-
     portable extension, and its use will nearly guarantee that a shell script will not execute properly on another system.

EXIT STATUS

     The sleep utility exits 0 on success, and >0 if an error occurs.

EXAMPLES

     To schedule the execution of a command for x number seconds later (with csh(1)):

	   (sleep 1800; sh command_file >& errors)&

     This incantation would wait a half hour before running the script command_file.  (See the at(1) utility.)

     To reiteratively run a command (with the csh(1)):

	   while (1)
		   if (! -r zzz.rawdata) then
			   sleep 300
		   else
			   foreach i (`ls *.rawdata`)
				   sleep 70
				   awk -f collapse_data $i >> results
			   end
			   break
		   endif
	   end

     The scenario for a script such as this might be: a program currently running is taking longer than expected to process a series of files, and
     it would be nice to have another program start processing the files created by the first program as soon as it is finished (when zzz.rawdata
     is created).  The script checks every five minutes for the file zzz.rawdata, when the file is found, then another portion processing is done
     courteously by sleeping for 70 seconds in between each awk job.

SEE ALSO

     nanosleep(2), sleep(3)

STANDARDS

     The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.

HISTORY

     A sleep command appeared in Version 4 AT&T UNIX.

BSD
								  April 18, 1994							       BSD

Linux and UNIX Man Pages

sleepenh(1) [debian man page]

Check Out this Related Man Page