Running A command within a function Shell Script

Question

I'm at a loss here. I'm trying to create a script to automate some things. I have a function exitfn() it is supposed to catch the ctrl+c and execute. I do this because, if you look, below the function this operation sometimes hangs and I only need to run it. It does not finish so I tell the ask the user to hit ctrl+c and it should run the function but instead I get back:

/bin/grep: /var/lib/mrtg/cfgs/ .cfg: No such file or directory.

My thoughts:

Is it even running the first comman correctly?

Am I using the whole trap thing wrong?

#!/bin/bash
echo "Enter the name of the device: > "
read dName
echo "Now enter device type [cpu, ram, : > "
read dType
echo "Enter the devices actual value with % symbol: > "
read aValue
echo "Enter the desired threshold with % symbol: > " 
read dValue
echo "Grounding..." 
n=`locate thresholdHandler.pl`
cd ${n%thresholdHandler.pl}
echo "Hit Ctrl+C to continue......"

exitfn() {
    trap SIGINT
    echo; 
        echo "Running second command, wait 3 seconds"  
        sleep 3
        ./thresholdHandler.pl output above $dname.$dType $dValue $aValue
        echo "Complete"
    exit
}

trap "exitfn" INT
./thresholdHandler.pl output above $dName.$dType $aValue $dValue
sleep 10
trap SIGINT

Thank You for your time.

I removed that the issue was still not resolved. I will reflect this on my original post. — Kirs Kringle
– Kirs Kringle, Commented Jul 22, 2014 at 9:10
The pl script is not the issue the first one works and the second one is only a variation. — Kirs Kringle
– Kirs Kringle, Commented Jul 22, 2014 at 9:17
Yeah, that's what I thought :) I edited my original answer to address this point — Aserre
– Aserre, Commented Jul 22, 2014 at 9:48

Aserre · Accepted Answer · 2014-07-22 09:33:45Z

2

You use trap way too much in your script :)

Your code should look like this :

echo "Hit Ctrl+C to continue......"

exitfn() {
    trap "" SIGINT    #we trap any further ctrl + c and force execution of exitfn
    echo; 
        echo "Running second command, wait 3 seconds"  
        sleep 3
        ./thresholdHandler.pl output above $dName.$dType $dValue $aValue
        echo "Complete"
    exit 0
}

trap "exitfn" SIGINT    #here, only ctrl+c is trapped. Add more signals here if needed
./thresholdHandler.pl output above $dName.$dType $aValue $dValue
sleep 10

Generally speaking, the correct usage of trap is trap "instructions" SIGNAL[S]. Once you put that line in your script, the trap will be active for all the instructions below (the ones before won't trigger your trap).

If you want to force-wait the execution of your perl script in your exit function, just trap the SIGINT and execute nothing.

Concerning your 1st point, yes, thresholdHandler.pl will be run. However, it will be run 2 times if you hit CTRL+C (once by the regular script, though not fully as it is interupted by SIGINT, and once by the exitfn when it is called by the trap), with different values (I don't know if this is intended or a simple typo in copying the exmaple).

edited Jul 22, 2014 at 9:33

answered Jul 22, 2014 at 9:22

Aserre

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3 Comments

Kirs Kringle Over a year ago

I only want the one below to run for a few seconds then you cancel out then the second one runs till end.

Aserre Over a year ago

@KirsKringle so, you want the 1st script executed for 10 seconds, then interupted, then wait for the user to press ctrl+c, then run the exit function ?

Kirs Kringle Over a year ago

Essentially what you have is exactly what I want. Just think of the pl script being some sort of auditing thing. The first one runs and runs sometimes, but the user knows that it does that and that it does not need to so they go ahead and cancel it.

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