15 Debugging scripts
Earlier in Section 5 a number of ways to run a script were presented. There is yet another, which
makes debugging easier. If you invoke the script with the csh command you can specify none or one
or more options. The command takes the form
script is the file. There is a choice of two debugging options.
The x option echoes the command lines after variable substitution, and the v option echoes the
command lines before variable substitution. The v is normally used to identify the line at which the
script is failing, and the x option helps to locate errors in variable substitution. As these options can
produce lots of output flashing past your eyes, it is often sensible to redirect the output to a file to be
examined at a comfortable pace.
% csh -x myscript
% csh -v myscript
If you prefer, you can run the script in the normal way by putting the option into the first comment