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Naib
Watchman
Joined: 21 May 2004
Posts: 6051
Location: Removed by Neddy
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 Posted: Mon Mar 30, 2015 9:03 pm Post subject: Bash and external loop control |
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Say I wanted a while loop in bash, could I exit the loop from another bash instance?
I was thinking about using mkfifo
| Code: |
mkfifo /tmp/fifo
while true
do
if read line /tmp/fifo; then
if [[ "$line" == 'quit' ]]; then
break
fi
echo $line
fi
done
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This obviously waits for each echo "test" > /tmp/fifo and finally quits on echo "quit" > /tmp/fifo but what if I wanted to keep the loop running and wait for some external (to the process or the subprocess which is the while loop) to quit the loop?
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frostschutz
Advocate
Joined: 22 Feb 2005
Posts: 2977
Location: Germany
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| Posted: Mon Mar 30, 2015 9:09 pm Post subject: |
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You could use 'trap' and then do something on kill.
Or just write quit to the fifo as it were... anyone can write quit, right? |
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Naib
Watchman
Joined: 21 May 2004
Posts: 6051
Location: Removed by Neddy
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| Posted: Mon Mar 30, 2015 9:16 pm Post subject: |
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Just been looking into trap, that might be a cleaner method
The problem with the fifo is it blocks on the read so it doesn't allow the loop to essentially run async to any incoming signal - thus trap/kill might be better
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