CODEWITHSUNDEEP
bash
user2647717
user2647717

Reputation: 129

Execute a timed function in bash

I am trying to implement a timed function. If the timer times out the function/command should be killed. If the function/command finishes, the timer should not make the bash to wait for the timer to timeout.

(cmdpid=$BASHPID; \
    ( sleep 60; kill $cmdpid 2>/dev/null) &  \
    child_pid=$!; \
    ssh remote_host /users/jj/test.sh; \
    kill -9 $child_pid)

The test.sh may or may not finish in 60 seconds. This worked fine.

But when I want to get the result of the test.sh, which echoes "SUCESS" or "FAILURE", I tried with 

result=$(cmdpid=$BASHPID; \
    ( sleep 60; kill $cmdpid 2>/dev/null) &  \
    child_pid=$!; \
    ssh remote_host /users/jj/test.sh; \
    kill -9 $child_pid)

Here it waits for timer to exit. I can see the "kill -9 $child_pid" is executed, using set -x command, but the kill is not really killing the sub-shell.

Upvotes: 3

Views: 1222

Answers (2)

user2647717
user2647717

Reputation: 129

Found some other way.

result=$( ssh $remote_host /users/jj/test.sh ) & mypid=$!
( sleep 10; kill -9 $mypid ) &
wait $mypid

Upvotes: 1

Jamil Said
Jamil Said

Reputation: 2093

One way to tackle this problem would be to run the timer on a separate script, say MyTimerTest, which is called from the (say) MainScriptTest but runs separately, and then whichever script that finishes first "kills" the other. For example:

On MainScriptTest you could put this at the beginning:

nohup /folder/MyTimerTest > /dev/null 2>&1 &

On MainScriptTest you could put this at the very end:

killall MyTimerTest > /dev/null 2>&1

The MyTimerTest could be something like this:

#!/bin/bash
sleep 60
killall MainScriptTest > /dev/null 2>&1
exit 0

Note: the long name for the scripts with mixed capital and lowercase letters (ex.: MainScriptTest) is on purpose, killall is case sensitive and that helps to preclude it from killing something it should not. To be very safe, you might want to even add a token in addition to the longer name, like: MainScriptTest88888 or something like that.

Edit: Thanks to gilez, who suggested the use of the timeout command. If that is available to you on your system, one could do a quick one-liner like this:

timeout 60 bash -c "/folder/MainScriptTest"

Using timeout is convenient. However, if MainScriptTest creates independent child processes (for example by calling: nohup /folder/OtherScript &) then timeout would not kill those child processes, and the exit would not be clean.

The first solution I gave is longer, but it could be customized to kill those child processes (or any other processes you want) by adding them to the MainScriptTest, like for example:

killall OtherScript > /dev/null 2>&1

Upvotes: 1

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