Debugging shell scripts

konstantinmiller · 06-05-2006, 06:48 AM

Hi!

Is there any possibility to automatically stop bash script execution after each command and continue after for example a key press?

Thanks for advices!

Konstantin

Hobbletoe · 06-05-2006, 07:02 AM

Just put a read statement in after each statement. If you want any key press to work, do a

Code:

read -n 1

That way, it will automatically return after the first character typed.

konstantinmiller · 06-05-2006, 07:26 AM

:-) That's not what I mean by automatically! I would not like to modify the script! And with read I wouldn't be able to stop after commands embedded in ``!

Hobbletoe · 06-05-2006, 08:01 AM

I can not say that I know of a way to do that. You might want to look into the --debugger option for bash to see if there is anything there that will help you to debug a script.

gnashley · 06-07-2006, 02:41 AM

You could write a small function with all the code and exit option.

Then by calling it later, even back-ticked it could exit or continue.

jlinkels · 06-07-2006, 12:03 PM

No, bash doesn't offer that capabilities. It stated explicitely in the advanced bash scripting guide. However, if you call:

Code:

sh -x myscript.sh

from the command line you'll get a trace on your screen with all steps the program has taken.

jlinkels

paulsm4 · 06-07-2006, 12:28 PM

Hi -

I don't think there's any "Visual Studio-like" IDE for debugging, if that's what you mean.

Usually a few debug "echo" statements (the shell equivalent of "printf") is all you need.

"bash/sh/ksh -x myscript" is a good technique.

Equivalently, you can also add a "set -x" at the part of the script where you want to start tracing, and a corresponding "set +x" where you want to stop tracing.

Here's a good overview (one of many, similarly good tutorials):
http://mercury.chem.pitt.edu/~sasha/...ticle216.shtml

'Hope that helps .. PSM

johnMG · 06-07-2006, 12:39 PM

Instead of running the code as a script, just type it in line by line at your shell prompt.

Bam. Interactive debugging.

gnashley · 06-07-2006, 02:15 PM

Perhaps have a look at the program execline which executes code by lines. feed each command to execline and include a read.

nx5000 · 06-08-2006, 05:33 AM

In bash,
you can put :

Code:

set -x

at the beginning of your script

Same for this line, it will redirect all stdout (echo,..) to a file

Code:

script 1> /tmp/myshell.log

This one will redirect all output to /dev/null and then your script will be "mute"

Code:

script 1> /dev/null

The advantage is you don't need to modify your entire script.