How do I manipulate $PATH elements in shell scripts?

Question

Is there a idiomatic way of removing elements from PATH-like shell variables?

That is I want to take

PATH=/home/joe/bin:/usr/local/bin:/usr/bin:/bin:         


        

Answer 1

There are a couple of relevant programs in the answers to "How to keep from duplicating path variable in csh". They concentrate more on ensuring that there are no repeated elements, but the script I provide can be used as:

export PATH=$(clnpath $head_dirs:$PATH:$tail_dirs $remove_dirs)

Assuming you have one or more directories in $head_dirs and one or more directories in $tail_dirs and one or more directories in $remove_dirs, then it uses the shell to concatenate the head, current and tail parts into a massive value, and then removes each of the directories listed in $remove_dirs from the result (not an error if they don't exist), as well as eliminating second and subsequent occurrences of any directory in the path.

This does not address putting path components into a specific position (other than at the beginning or end, and those only indirectly). Notationally, specifying where you want to add the new element, or which element you want to replace, is messy.