How to create "workers" using bash?

Question

I'd like to run some different scripts simultanously using bash. All of them say something to an screen-session.

What we have:

worker=1

while [[ ! -f "worker$worker.sh" ]]; do
if [[ ! -f "worker$worker.sh" ]]; then

cat >worker$worker.sh <<EOL

#some code with variables which change and say something to an screen session#

EOL

chmod a+x worker$worker.sh 
./worker$worker.sh
break
else
(( worker ++ ))
continue
fi
done

The current code does not work :/ What's wrong?

Welcome to stackoverflow! Consider including a description of what you expected to happen and then a description of what actually happens (including any commands you run and what they output). It's especially helpful if people can see the same behavior by running your posted script themselves (instead of you running a different/full version and then reporting on what that does without letting anyone see the code) — that other guy
– that other guy, Commented Apr 10, 2017 at 18:53
Please add a simple example of "saying something to a screen session". — Mark Setchell
– Mark Setchell, Commented Apr 10, 2017 at 21:31

Ole Tange · Accepted Answer · 2017-04-17 14:47:32Z

3

tmux is an alternative to screen.

GNU Parallel has an interface to tmux, so try this:

parallel --fg --delay 0.1 --tmuxpane ::: worker*.sh
parallel --fg --delay 0.1 --tmux ::: worker*.sh

If you do not need the tmux interface:

parallel ::: worker*.sh

Start by watching the intro videos for a quick introduction: http://www.youtube.com/playlist?list=PL284C9FF2488BC6D1

Then look at the EXAMPLEs after the list of OPTIONS (Use LESS=+/EXAMPLE: man parallel). That will give you an idea of what GNU parallel is capable of.

Then spend an hour walking through the tutorial (man parallel_tutorial). Your command line will love you for it.

edited Apr 17, 2017 at 14:47

answered Apr 10, 2017 at 23:45

Ole Tange

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2 Comments

Mark Setchell Over a year ago

I have never seen GNU Parallel used with tmux! I tried a simple example and it says Can't join a pane to its own window? I just did parallel --fg --tmuxpane 'echo {}; sleep 3' ::: 4 5 6 7

Ole Tange Over a year ago

Yeah. You experience a race condition. Add --delay 0.1.

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