Use the following to define the interpreter to be used by the shell script (bash in our case):
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#!/bin/bash
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Arguments
variables that are passed to the script. These are also called parameters
$0 - the name of the script
$1 - first parameter from the script
$2 - second parameter from the script and so on
Example Script
See the example script below - script checks the IP with a ping command:
See the list of available conditions below:
![expression] - the expression is false
-n [string] - the length of the string is greater than zero
-z [string] - the length of the string is zero
string1 = string2 - string is equal to sting2
string1 != string2 - string is not equal to sting2
integer1 -eq integer2 - integer1 is equal integer2
integer1 -gt integer2 - integer1 is greater than integer2
integer1 -lt integer2 - integer1 is less than integer2
-d [file] - the file exists and is a directory
-e [file] - the file exists
-r [file] - the file exists, and the read permission is granted
-s [file] - the file exists, and its size is greater than zero
-w [file] - the file exists, and the write permission is granted
-x [file] - the file exists, and the execute permission is granted
* This section was copied from the Linux Academy course: LPI Linux Essentials Certification created by Michael Christian -- you can find it here.