Why do sleep & wait in bash?

Question

I\'m having trouble understanding the startup commands for the services in this docker-compose.yml. The two relevant lines from the .yml are:

command: \"/bin/sh          


        

Answer 1

The only reason I see:

If you killall -INT sleep, this won't affect main script.

Try this:

while true ;do sleep 12; echo yes;done

Then send a Interrupt signal:

killall -INT sleep

This will break the job!

Try now

while true ;do sleep 12 & wait $! ; echo yes;done

Then again:

killall -INT sleep

Job won't break!

Sample output, hitting killall -INT sleep from another window:

user@myhost:~$ while true ;do sleep 12; echo yes;done
break

user@myhost:~$ while true ;do sleep 12 & wait $! ; echo yes;done
[1] 30632
[1]+  Interrupt               sleep 12
yes
[1] 30636
[1]+  Interrupt               sleep 12
yes
[1] 30638
[1]+  Interrupt               sleep 12
yes
[1] 30640