topic Re: Debugging scripts KSH in Operating System - HP-UX

Debugging scripts KSH

Enrico Venturi — Thu, 15 May 2003 12:15:49 GMT

Hello colleagues,
are there any tools to execute step by step a KSH script?
sorry for the stupid question :-)

Enrico

Re: Debugging scripts KSH

Steve Steel — Thu, 15 May 2003 12:20:26 GMT

Hi

See set options in manpage and put

At the start of the script

-p Disables processing of the $HOME/.profile file and
uses the file /etc/suid_profile instead of the ENV
file. This mode is on whenever the effective uid
(gid) is not equal to the real uid (gid). Turning
this off causes the effective uid and gid to be
set to the real uid and gid.
-s Sort the positional parameters.
-t Exit after reading and executing one command.
-u Treat unset parameters as an error when
substituting.
-v Print shell input lines as they are read.
-x Print commands and their arguments as they are
executed.
- Turns off -x and -v options and stops examining
arguments for options.
-- Do not change any of the options; useful in
setting $1 to a value beginning with -. If no
arguments follow this option, the positional

Steve Steel

Re: Debugging scripts KSH

Robert-Jan Goossens — Thu, 15 May 2003 12:25:42 GMT

add the line

set -x

in the second line of your script.

Robert-Jan.

Re: Debugging scripts KSH

James R. Ferguson — Thu, 15 May 2003 12:36:39 GMT

Hi Enrico:

Steve has listed some of the more useful options.

You can leverage these without modifing your script by simply doing, for example:

# ksh -x yourscript

Another useful technique is to have 'trap' statements in your script for DEBUG and ERR. For example:

# trap 'echo Debug handler entered' DEBUG
# trap 'echo Error handler entered' ERR

See the 'sh-posix' or 'ksh' man pages for more information.

Regards!

...JRF...

Re: Debugging scripts KSH

Massimo Bianchi — Thu, 15 May 2003 12:46:51 GMT

Hi,
another little trick.

If after setting the debug mode (i call it so) you want to log everything, you can use the "script filename" command.

this utility let you dump all video output (std out and std err) and your input to the file mentioned, very usefull for debugging purpose.

Massimo

Re: Debugging scripts KSH

James R. Ferguson — Thu, 15 May 2003 13:16:33 GMT

Hi (again) Enrico:

Here's another example of how you might leverage the DEBUG signal to monitor your script. Remember that the trap could be set and reset around regions of your code. Hence, consider this example

#/usr/bin/ksh
echo "hello world!"
[ X"$1" = X-d ] && trap 'echo "@line-${LINENO}' DEBUG
echo "where am I?"
date
[ X"$1" = X-d ] && trap '' DEBUG
echo "debug mode off"
date
echo "where am I?"
exit 0

Run the script this way:

# ./my.sh

...then, with debug mode on:

# ./my.sh -d

Regards!

...JRF...