shorten a given pathname by compressing all /paths/leading/to/pathname into single character /p/l/t/pathname

condensepath.sh

#!/bin/bash

# shorten a given pathname by compressing all
# /paths/leading/to/pathname into single character /p/l/t/pathname

function condensepath {
        local PATHNAME="$1"
        local REGEX='(.*/)(.)[^/]+(/.+)'
        # https://stackoverflow.com/a/22261454
        while [[ "$PATHNAME" =~ $REGEX ]]
        do
                PATHNAME="${BASH_REMATCH[1]}${BASH_REMATCH[2]}${BASH_REMATCH[3]}"
        done
        echo "$PATHNAME"
}

FULLPATH="/paths/leading/to/pathname"
printf "%s -> %s\n" "$FULLPATH" "$(condensepath "$FULLPATH")"