title: Bash Variable Substitution
tags: linux bash variable

## Changing case to upper or lower
Sources: [scriptingosx.com](https://scriptingosx.com/2019/12/upper-or-lower-casing-strings-in-bash-and-zsh/)
```bash
$ name="John Doe"
$ echo ${name,,}
john doe

$ echo ${name^^}
$ JOHN DOE

$ name="JOHN"
$ echo "${name,}"
jOHN

$name="john"
$echo "${name^}"
John
```
For zsh
```zsh
% name="John Doe"
% echo ${name:l}
john doe
% echo ${name:u}
JOHN DOE
```