Sams Teach Yourself Shell Programming in 24 Hours, Second Edition

Enabling Debugging

By now, you are quite familiar with the basic syntax for executing a shell script:

$ script
						arg1
						arg2 ... argN
					

Here script is the name of the script and arg1 through argN are the arguments to the script.

An alternative method to execute a shell script is

$ /bin/sh opt
						script
						arg1
						arg2 ... argN
					

This invokes the shell, in this case /bin/sh, with the debugging option specified by opt and instructs the shell to execute script. Table 20.1 lists the various debugging options.

A second way to enable debugging is to change the first line of script. Usually, the first line of a script is

#!/bin/sh

UNIX uses this line to determine the shell you can use to execute a script. This indicates that the shell /bin/sh should be used to ...