How to remove a path from $PATH variable in fish?

I am using fish as my shell in Debian and recently (after some upgrade) whenever I try to use command completion I have:

set: No such file or directory
set: Could not add component /usr/lib/x86_64-linux-gnu/libfm to PATH.
set: No such file or directory

Running this:

echo $PATH 

Gives me this:

/usr/lib/x86_64-linux-gnu/libfm /usr/local/bin /usr/bin /bin /usr/local/games /usr/games

In my system there is no /usr/lib/x86_64-linux-gnu/libfm, so I understand why fish is complaining, but I cannot find how to remove this path from my $PATH variable.

Does anyone know how can I do this?

The 'fish' way of setting the $PATH variable is to actually use set --universal fish_user_paths $fish_user_paths /new/path/here. Then $fish_user_paths is actually prepended to the $PATH variable when a new session starts. The $PATH documentation doesn't currently tell you how to delete it though.

In fish every variable is actually a list (array), and you can conveniently access each item directly by using an index/indice. echo $fish_user_paths will print out a space delimited version of every item in the list, make the spaces newline with the translate function echo $fish_user_paths | tr " " "\n" and then put line numbers on it with the number lines function, echo $fish_user_paths | tr " " "\n" | nl. Then delete it with set --erase --universal fish_user_paths[5]. You must use --universal or it will not work in any new sessions.

If someone has the time, please submit a PR to the repo with this example. I opened an issue here.

tldr;

1. echo $fish_user_paths | tr " " "\n" | nl // get the number of the one you want to delete, e.g. the 5th one
2. set --erase --universal fish_user_paths[5] // erase the 5th path universally so it persists in new sessions

As Elijah says, best practice is to modify the fish_user_paths rather than the global PATH. To avoid ever having to Google this again…

1. Create a couple of functions that only modify fish_user_paths
2. Make both functions autoloading

To add to user paths:

function addpaths
    contains -- $argv $fish_user_paths
       or set -U fish_user_paths $fish_user_paths $argv
    echo "Updated PATH: $PATH"
end

To remove a user path if it exists (partial credit to this):

function removepath
    if set -l index (contains -i $argv[1] $PATH)
        set --erase --universal fish_user_paths[$index]
        echo "Updated PATH: $PATH"
    else
        echo "$argv[1] not found in PATH: $PATH"
    end
end

And of course, to make them autoloading:

funcsave addpaths; funcsave removepath

Example Usage:

> addpaths /etc /usr/libexec
Modifying PATH: /usr/local/bin /usr/bin /bin /usr/sbin /sbin
Updated PATH: /etc /usr/libexec /usr/local/bin /usr/bin /bin /usr/sbin /sbin

> removepath /usr/libexec
Modifying PATH: /etc /usr/libexec /usr/local/bin /usr/bin /bin /usr/sbin /sbin
Updated PATH: /etc /usr/local/bin /usr/bin /bin /usr/sbin /sbin

This should erase paths 6 through the last path:

set -e PATH[6..-1]

The -e flag is erase. See help set.