Working with command-line arguments (special variables, set and shift, getopt)

Command-line arguments are required for the following reasons:

• They inform the utility, or they command which file or group of files to process (reading/writing of files)
• Command-line arguments tell the command/utility which option to use

Check out the following command line:

[student@localhost ~]$  my_program  arg1  arg2  arg3

If my_command is a bash shell script, then we can access every command-line positional parameter inside the script, as follows:

$0 would contain "my_program"          # Command 
$1 would contain "arg1"                # First parameter 
$2 would contain "arg2"                # Second parameter 
$3 would contain "arg3"                # Third parameter

The following is a summary of the positional parameters:

$0	Shell-script name or command
$1-$9	Positional parameters 1-9
${10}	Positional parameter 10
$#	Total number of parameters
$*	Evaluates for all the positional parameters
$@	Same as $*, except when double...