Scribbles for my bad memory

, change the first letter of the value of the variable to lowercase, ,, change the value of the whole variable to lower case.

$ test='HELLO'
$ echo $test
HELLO
$ echo ${test,}
hELLO
$ echo ${test,,}
hello
$ test=${test,,}
$ echo ${test^}
Hello
$ echo ${test^^}
HELLO