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1.7  Debugging Scripts

Problem

You want to see commands in a initialization (or other) script, as they are being executed.

Solution

Use the -xv shell options. This is similar in effect to the DCL command SET VERIFY.

Discussion

The -x shell option prints commands and their arguments as they are executed. The -v option prints shell input lines (i.e. the script's source code lines) as they are read.

There are three basic ways of turning on script verification:

1. Invoke the shell with these options on the command line.

   unix> sh -xv myScript.sh | more
   

   Be forewarned that just like SET VERIFY this can produce a lot of output, so you may want to pipe the resulting text through a pager or redirect it to a temp file.

2. Invoke the options on the initial 'shebang' line of the script:

        #!/bin/sh -xv

   (See 3.1 for more information about the shebang line.)

3. Use the ksh set command to turn these options on and off as needed:

        set -x;   # Turn on tracing with variable substitution...
         :
         :
        unset -x; # Turn off tracing...

See Also

3.1 - Creating Shell Scripts;
Chapter 10 of Unix for OpenVMS Users ;
Chapter 48 of Unix Power Tools .

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This page maintained by:     Bill.Costa@unh.edu     of the Enterprise Computing Group     in the dept of Computing & Information Sevices     at the University of New Hampshire	Typographical Conventions Created:  31-Jan-2001 BC Revised:  27-Mar-2001 BC