Bash Script Knowledge Base

This article holds some notes about scriping in bash.

Siehe auch: Shell-Skript How-To (Linux)

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

Source: https://www.geeksforgeeks.org/bash-script-working-of-bash-variables/

Check if Bash Script Received Parameters

Check if any arguments were passed to the script:

if [ $# -eq 0 ]; then
  echo "No arguments received"
else
  echo "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"
else
  echo "Argument 1 is $1"
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.

Sources:

https://stackoverflow.com/questions/6482377/check-existence-of-input-argument-in-a-bash-shell-script

https://www.w3schools.com/bash/bash_conditions.php