Bash Script: catching errors in a block of statements

plumb_pete

I have a large iptables ruleset that I manage with my own bash script. Most of the commands in the script are simple, single-statment iptables commands. I am trying to improve the script by adding success/failure output as the script executes. I have the script broken out into different sections. One example would be the FORWARD chain section, where all the rules are applied to the FORWARD chain. At the beginning of the section, I output that...

Originally asked by Miles Stevenson on Stack Exchange (askubuntu) (CC BY-SA 3.0).

uphilltech

Great question — answering as the UphillTech team:

You could use the trap shell builtin command to have a handler function called if a command has a non-zero exit status. You can pass necessary information, like the line number and the exit status to your error handler function. Example: #!/bin/bash handle_error() { echo "FAILED: line $1, exit code $2" exit 1 } trap 'handle_error $LINENO $?' ERR # your commands here # ... echo "OK"

Full answer by Jukka Matilainen: https://askubuntu.stackexchange.com/a/53765 (CC BY-SA 3.0).

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