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[BASH] Script to manage background scripts (running, finished, exit code)

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Top Forums Shell Programming and Scripting [BASH] Script to manage background scripts (running, finished, exit code)
# 8  
Old 10-16-2014
@sea On systems with /proc [ -d /proc/$PID ] is a nice and efficient alternative to using ps ... | grep $PID | grep -v grep

@Corona688 Interesting script - Is it up to the caller to ensure they dont exceed MAX jobs on calling (I cant spot anything that limits the number of background jobs started).
# 9  
Old 10-16-2014
Quote:
Originally Posted by Chubler_XL
@Corona688 Interesting script - Is it up to the caller to ensure they dont exceed MAX jobs on calling (I cant spot anything that limits the number of background jobs started).
The while [[ "$TOTAL" -ge "$MAX" ]] loop waits until one quits.

Even on systems without /proc, you can just do "ps pid" and it will return true if it exists and false if it doesn't, no need to grep | awk | sed | kitchen | sink.
# 10  
Old 10-16-2014
Quote:
Originally Posted by Corona688
The while [[ "$TOTAL" -ge "$MAX" ]] loop waits until one quits.
Oh yes I see it now - think I missed it due to the indenting Smilie
# 11  
Old 10-16-2014
Quote:
Originally Posted by Corona688
The while [[ "$TOTAL" -ge "$MAX" ]] loop waits until one quits.

Even on systems without /proc, you can just do "ps pid" and it will return true if it exists and false if it doesn't, no need to grep | awk | sed | kitchen | sink.
If you save the PIDs when you fire up a background job:
Code:
job& pid=$!

an even faster way to find out if the job is still running is:
Code:
if kill -0 $pid 2>&/dev/null
then    echo "$pid is still running"
else    echo "$pid is no longer running"
fi

# 12  
Old 10-16-2014
First time I've seen this approach does this actually signal the running process in any way?

Do you know how portable this zero signal is?
# 13  
Old 10-16-2014
kill is faster than ps? I think they're both externals..
# 14  
Old 10-16-2014
Kill is a built-in on a lot of shells, probably because it needs to be aware of jobs. aka kill %1.
This User Gave Thanks to Chubler_XL For This Post:
Corona688
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