How to debug/trace bash function?

Question

I have a bash script myscript.sh, which has a bunch of functions inside. To run one function, I would write

source myscript.sh; myfunction

How debug such a function?

Related: How to debug a bash script – Mark Plotnick May 29 '19 at 22:47 — Mark Plotnick, May 29 '19 at 22:47

score 6 · Answer 1 · answered May 29 '19 at 16:15

6

Just add these line before section you want to debug.

set -v -x -e

and to disable it.

set +v +x +e

answered May 29 '19 at 16:15

asktyagi

675

score 2 · Answer 2 · answered May 29 '19 at 16:13

2

enable debugging in your script and output debugging for functions with functrace.

set -x
set -o functrace

answered May 29 '19 at 16:13

αғsнιη

41,407

Is there any way to direct the output this produces to a log file? – Britton Kerin Apr 16 '23 at 18:02
@BrittonKerin yourScript.sh 2>1& >output_to_file. – αғsнιη Apr 17 '23 at 05:16

PJF · Answer 3 · 2019-05-29T17:08:46.900

You should also in Bash be able to use:

$ set -xT

which enables function trace and

$ set +xT

to disable.

Also, with reference to another posted answer, I don't recommend using -v for debugging (verbose mode) unless you are checking a script/set of shell commands for syntax. One other (general) solution that is sometimes useful is making use of the -n option in conjunction with -x. This will "run" a script/commands without actually doing the last step of running a command. This can often let you pick up difficult errors in shell expansions and the like without causing unwanted mayhem.

How to debug/trace bash function?

3 Answers3