Linux Shell Scripting Cookbook - Third Edition

How to do it...

We can either use Bash's inbuilt debugging tools or write our scripts in such a manner that they become easy to debug; here's how:

1. Add the -x option to enable debug tracing of a shell script.

        $ bash -x script.sh

Running the script with the -x flag will print each source line with the current status.

You can also use sh -x script.

2. Debug only portions of the script using set -x and set +x. Consider this example:

        #!/bin/bash 
        #Filename: debug.sh 
        for i in {1..6}; 
        do 
            set -x 
            echo $i 
            set +x 
        done 
        echo "Script executed"

In the preceding script, the debug information for echo $i will only be printed, as debugging is restricted to that section using -x and +x. The script uses the {start..end} construct to iterate from a start ...