Reputation: 33
(Sorry for my bad english.) I would like to pause a running script by pressing the [SPACE] bar. The script must run, until the user not press the [SPACE] bar, then pause 20 seconds, and run forth. How can i continuously watch the keyboard input while the script is running?
Upvotes: 3
Views: 693
Reputation: 85
I suggest to use a controlling script that freezes you busy script:
kill -SIGSTOP ${PID}
and then
kill -SIGCONT ${PID}
to allow the process to continue.
see https://superuser.com/questions/485884/can-a-process-be-frozen-temporarily-in-linux for more detailed explanation.
Upvotes: 0
Reputation: 60056
One way to do it:
#!/bin/bash -eu
script(){ #a mock for your script
while :; do
echo working
sleep 1
done
}
set -m #use job control
script & #run it in the background in a separate process group
read -sd ' ' #silently read until a space is read
kill -STOP -$! #stop the background process group
sleep 2 #wait 2 seconds (change it to 20 for your case)
kill -CONT -$! #resume the background process group
fg #put it in the forground so it's killable with Ctrl+C
Upvotes: 3
Reputation: 4205
I think the most simple way is to implement a script with checkpoints, which tests if a pause is required. Of course, it means your code never call 'long' running command...
A more complex solution is to use SIGPAUSE signal. You can have the main process that execute the script and the side process that catches [SPACE] and emit SIGPAUSE to the main process. Here I see at least two issues: - how to share the terminal/keyboard between the 2 process (simple if your main script don't expect input from keyboard), - if the main script starts several processes, you will have to deal with process group...
So it really depends on the complexity of your script. You may consider to rely only on regular Job control provided by Bash.
Upvotes: 0