First Line of Script

• #!/bin/bash → defines the shell interpreter

Comments

• Use # for commenting

Common Elements

• Commands: echo, cp, etc.
• Statements: if, while, for
• +x → make the script executable
• Use absolute path to run: /home/userdir/myscript.bash

Variable Definition

a=hello
b=mytext

• Usage:

echo "text1 $a"
echo "text2 $b"

• Example:

a=$(hostname)
echo $a  # => myfirstlinux

Input / Output Variable

read myinputvariable
echo "name $myinputvariable"

If Else Statement

if [[ $count -eq 100 ]]; then
  echo "count is 100"
else
  echo "no"
fi

File Existence Check

if [[ -e /file.txt ]]; then
  echo "file exists"
fi