How to keep from duplicating path variable in csh

Question

It is typical to have something like this in your cshrc file for setting the path:

set path = ( . $otherpath $path )

but, the path gets dup

Answer 1

When setting path (lowercase, the csh variable) rather than PATH (the environment variable) in csh, you can use set -f and set -l, which will only keep one occurrence of each list element (preferring to keep either the first or last, respectively).

https://nature.berkeley.edu/~casterln/tcsh/Builtin_commands.html#set

So something like this

cat foo.csh # or .tcshrc or whatever: set -f path = (/bin /usr/bin . ) # initial value set -f path = ($path /mycode /hercode /usr/bin ) # add things, both new and duplicates

Will not keep extending PATH with duplicates every time you source it:

% source foo.csh % echo $PATH % /bin:/usr/bin:.:/mycode:/hercode % source foo.csh % echo $PATH % /bin:/usr/bin:.:/mycode:/hercode

set -f there ensures that only the first occurrence of each PATH element is kept.