emanuele6 1628791057 learn Quotes expanding in math contexts is a bash-specific feature. If you must use substitutions in a math context (e.g. you need to do maths on $?, $# or ${#var}) and you are targeting POSIX sh, you should not quote those substitutions since the quotes are not guaranteed to expand: e.g. `echo "$(( "$#" + 1 ))"' causes a syntax error in dash and zsh; use `echo "$(( $# + 1 ))"' instead.