Bash Script Knowledge Base

This article holds some notes about scriping in bash.

General

A bash script starts in the first line with:

#!/bin/bash

Variables

Define variable MY_STR:

HW="Hello World!"

Read content of the variable and put it to the console:

echo $HW

Check if Bash Script Received Parameters

Check if any arguments were passed to the script:

if [ $# -eq 0 ] then
  echo "No arguments received"
fi

$# contains how many arguments were passed to the script.

Check if first argument was empty:

if [ -z "$1" ] then
  echo "Argument 1 empty"
fi

The -z switch will test, if the argument passed is empty. If it is empty, then the expression resolves to true and the body of the if statement is executed.