* remove * remove first character x in string

VAL=${VAL/__x__/}

* remove last character x in string

VAL=${VAL/__x__/}

* remove first n characters

VAL=${VAL:__n__}

* remove last n characters

VAL=${VAL::-__n__}

* extract * extract characters from position n to m

VAL=${VAL:__n__:__m__}