Automating frequent tasks

What to do if something goes wrong

If your shell script stubbornly refuses to work, there are two possibilities:

You are trying to execute the script in an inappropriate environment.
The script contains a bug.

An inappropriate environment means that the script is unable to run because the environment you are trying to run it in is not set up for it. For example, you cannot execute a Bourne shell script in the C shell with any expectation of success (unless you force the system to run the script under a Bourne shell by making the first line of the script #!/bin/sh). Alternatively, you may have forgotten to set the execute permission on the script, so that the shell fails to recognize it as a command. Or you may have told your script to read and act on an environment variable which is not present.