Shell (almost) regexp variable substitution
${variable#pattern}
If the pattern matches the beginning of the variable’s value, delete the shortest part that matches and return the rest. ${variable##pattern}
If the pattern matches the beginning of the variable’s value, delete the longest part that matches and return the rest. ${variable%pattern}
If the pattern matches the end of the variable’s value, delete the shortest part that matches and return the rest. ${variable%%pattern}
If the pattern matches the end of the variable’s value, delete the longest part that matches and return the rest.