CODEWITHSUNDEEP
bashparent-childkill
octosquidopus
octosquidopus

Reputation: 3713

Open and then kill child process from bash

What's the best way of executing a command and then killing it after some time? Here's what I have; it does the job, but I get amp: command not found and although I'm not sure why the amp is there in the first place, I know that the killing doesn't work without it.

feh "$output""$ext" &
echo $!
sleep 1
kill -s 9 $!
exit 1

The thing is that I don't know the PID of the process I'm executing. Could I assign one upon execution?

Upvotes: 3

Views: 4177

Answers (3)

daxelrod
daxelrod

Reputation: 2589

GNU timeout, part of recent versions of coreutils, does exactly what you want.

timeout 1 feh "$output""$ext"

runs feh for one second and then kills it, if it hasn't already ended.

The rest of this comment concerns your current recipe:

The recipe you're currently using puts feh into the background using the &. The amp; after it is a mistake, likely from some overzealous HTML encoder (& is how you spell & in HTML).

Every process is assigned a PID by the kernel when launched. $! is the shell variable for the pid of the most recently backgrounded process.

Upvotes: 7

Usman Saleem
Usman Saleem

Reputation: 1655

feh "$output""$ext" &
FEHPID=$!
sleep 1
kill -s 9 $FEHPID
exit 1

Upvotes: 4

mloar
mloar

Reputation: 1554

You don't want "&" you just want "&". The ampersand tells bash to run the process in the background.

The $! is set to the pid of the background process, so otherwise your sample should do what you want.

Upvotes: 4

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