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Full Discussion: Wrapping 'sleep' with my 'resleep' function (Resettable sleep)
Top Forums Shell Programming and Scripting Wrapping 'sleep' with my 'resleep' function (Resettable sleep) Post 302356482 by deckard on Friday 25th of September 2009 04:35:50 PM
Old 09-25-2009
Wrapping 'sleep' with my 'resleep' function (Resettable sleep)
This is a very crude attempt in Bash at something that I needed but didn't seem to find in the 'sleep' command. However, I would like to be able to do it without the need for the temp file. Please go easy on me if this is already possible in some other way:

How many times have you used the 'sleep' command interactively only to realize that the amount of time you initially specified wasn't enough and you wanted to reset it? Or how many times have you had something sleeping for quite a while but you wanted to know where it was in the sleep countdown? I've found myself in these situations quite a few times when recording a TV show or some other multimedia. So I wrote the 'resleep' functions (which wrap around 'sleep') below which can then either be included in scripts where you'd normally use sleep by itself, or dotted into your environment and run as commands. It's not polished and I'm positive the logic isn't clean, but it's working for me so far. One thing I still need to add is the ability to pass a unit of time (in seconds, minutes, hours) to the wrapped 'sleep' command itself so that my "time units" count can be something other than one second as it is now. For example it would be nice to be able to set it to 30 minutes and then three time units would be 90 minutes. But that will come later... So here it is in all it's ugliness...

SCRIPT EDIT: Demoggified per cfajohnson's comments. Thanks!

Code:
# 'resleep' is a resettable sleep countdown timer.  You specify the initial
# count of time units (in this case seconds).  Then if you need more time
# you echo the new time unit count to /tmp/.dtime which resets the count
# to whatever you specify.

function resleep()
{
timefile=/tmp/.dtime$$
echo $1 > $timefile
dur=$1

while ((dur > 0))
do
  sleep 1
  read dur < $timefile
  countdown=$(($dur-1))
  echo $countdown > $timefile
done

rm $timefile
}

# The 'setsleep' function is used to reset your time unit count.  Example:
# 'setsleep 30' will reset the count to 30 seconds.
# If the countdown is over an error message is presented.
function setsleep()
{
timefile=/tmp/.dtime

if ! [ -e $timefile ]
then
  echo "No countdown file present"
  return
fi

read dur < $timefile
echo "Current countdown: $dur"
echo $1 > $timefile
read dur < $timefile
echo "Reset countdown: $dur"
}

# The 'getsleep' function is used to see where you are in the countdown.
# If the countdown is over an error message is presented.
function getsleep()
{
timefile=/tmp/.dtime

if ! [ -e $timefile ]
then
  echo "No countdown file present"
  return
fi

read dur < $timefile
echo "Current countdown: $dur"
}

As a sidenote, I couldn't think of a good way to do this without using the temp file, although I would have preferred to avoid it. The problem is being able to write to a variable while it's in use. Is there some way to do this without the temp file?
Last edited by deckard; 09-28-2009 at 04:09 PM..
 

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LEARN ABOUT SUNOS

sleep

sleep(1)							   User Commands							  sleep(1)

NAME

       sleep - suspend execution for an interval

SYNOPSIS

       sleep time

DESCRIPTION

       The sleep utility will suspend execution for at least the integral number of seconds specified by the time operand.

OPERANDS

       The following operands are supported:

       time	A non-negative decimal integer specifying the number of seconds for which to suspend execution.

EXAMPLES

       Example 1: Suspending command execution for a time

       To execute a command after a certain amount of time:

       example% (sleep 105; command)&

       Example 2: Executing a command every so often

       example% while true
       do
	       command
	       sleep 37
       done

ENVIRONMENT VARIABLES

       See  environ(5) for descriptions of the following environment variables that affect the execution of sleep: LANG, LC_ALL, LC_CTYPE, LC_MES-
       SAGES, and NLSPATH.

EXIT STATUS

       The following exit values are returned:

       0	The execution was successfully suspended for at least time seconds, or a SIGALRM signal was received (see NOTES).

       >0	An error has occurred.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       wait(1), alarm(2), sleep(3C), wait(3UCB), attributes(5),  environ(5), standards(5)

NOTES

       If the sleep utility receives a SIGALRM signal, one of the following actions will be taken:

	 o  Terminate normally with a zero exit status.

	 o  Effectively ignore the signal.

       The sleep utility will take the standard action for all other signals.

SunOS 5.10							    1 Feb 1995								  sleep(1)
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