| `${#FOO}` | Length of `$FOO` |
+### Manipulation
+
+```bash
+STR="HELLO WORLD!"
+echo ${STR,} #=> "hELLO WORLD!" (lowercase 1st letter)
+echo ${STR,,} #=> "hello world!" (all lowercase)
+
+STR="hello world!"
+echo ${STR^} #=> "Hello world!" (uppercase 1st letter)
+echo ${STR^^} #=> "HELLO WORLD!" (all uppercase)
+```
+
+
### Default values
| `${FOO:-val}` | `$FOO`, or `val` if not set |