Arguments

Arguments, as well as being things I often get into at home about the jobs I forgot to do... are the things we pass to a command or script upon execution:

ls -l /opt

In the above command, there is one option (-l) and one argument, (/opt)

You can prescribe for arguments in your script using special variables:

• $0 - The name of the script being executed

• $1 - The FIRST command line argument passed

• $2 - The SECOND command line argument passed

So, let's look at an example script:

Example Script to handle Arguments: example.sh

#!/bin/bash

echo "Welcome to the $0 script."
echo "The first two arguments are $1 and $2"

So, if we pass the following command with arguments:

./example.sh apples pears
Welcome to the ./example.sh script.
The first two arguments are apples and pears

There are other special arguments we can use:

Argument	Description
$0	The name of the Bash script
$1 - $9	The first 9 arguments to the Bash script
$#	Number of arguments passed to the Bash script
$@	All arguments passed to the Bash script
$?	The exit status of the most recently run process
$$	The process ID of the current script
$USER	The username of the user running the script
$HOSTNAME	The hostname of the machine
$RANDOM	A random number
$LINENO	The current line number in the script