LEARN BASH SCRIPTING
- Any command that can be run in the terminal can be run in a bash script.
- Variables are assigned using an equals sign with no space (
greeting="hello"). - Variables are accessed using a dollar sign (
echo $greeting). - Conditionals use
if,then,else,fisyntax. - Three types of loops can be used:
for,while, anduntil. - Bash scripts use a unique set of comparison operators:
- Equal:
-eq - Not equal:
-ne - Less than or equal:
-le - Less than:
-lt - Greater than or equal:
-ge - Greater than:
-gt - Is null:
-z
- Equal:
- Input arguments can be passed to a bash script after the script name, separated by spaces (myScript.sh “hello” “how are you”).
- Input can be requested from the script user with the read keyword.
- Aliases can be created in the .bashrc or .bash_profile using the alias keyword.
Examples
Example 1
#!/bin/bash
first_greeting="Nice to meet you!"
later_greeting="How are you?"
greeting_occasion=0
greeting_limit=$1
while [ $greeting_occasion -lt $greeting_limit ]
do
if [ $greeting_occasion -lt 1 ]
then
echo $first_greeting
else
echo $later_greeting
fi
greeting_occasion=$((greeting_occasion + 1))
done
