Debugging shell scripts with line numbers

Question

I inherited a over 700 line shell script and noticed that when I ran the script it spits out error at some point of execution.

E.g error that I see on the console is something like

cat: /Wreck/wreck_module.rb: No such file or directory

I have tried to use set -x and most of the tips from this link, however I noticed that all the output that I was getting were pretty noisy.

Is there a way to get the exact line number of where a shell command returned a non-zero status?

perreal · Accepted Answer · 2013-07-06 03:36:59Z

5

Put this at the top of the script you want to debug:

#!/bin/bash
function trace_line(){
  caller
}
trap trace_line debug

and perhaps redirect the output to a file for easy analysis.

answered Jul 6, 2013 at 3:36

perreal

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2 Comments

What does this do? Is "caller" a built-in shell feature? Edit: yes, it is.

When I put it in the first few lines of the script, it seems that it cannot print the line number in the function, how can I modify it