convert a string to lower characters

strotolower.bash

# convert a string to lower characters
# @param string input

function strtolower()
{   
    [ -z "$1" ] && return 1
    printf "%s\\n" "$@" | tr 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' 'abcdefghijklmnopqrstuvwxyz' # tr '[:upper:]' '[:lower:]'
}