In a BASH Unix shell we can specify the options –v and –x on top of a script as follows:
#!/bin/bash -x –v
With –x option BASH shell will echo the commands like for, select, case etc. after substituting the arguments and variables. So it will be an expanded form of the command that shows all the actions of the script. It is very useful for debugging a shell script.
With –v option BASH shell will echo every command before substituting the values of arguments and variables. In –v option Unix will print each line as it reads.
In –v option, If we run the script, the shell prints the entire file and then executes. If we run the script interactively, it shows each command after pressing enter.Read the full book at www.amazon.com