Set $path fail (win10 subsystem linux, ubuntu, fish shell, brew)

Environment

OS: Windows Subsystem for Linux, Ubuntu 18.04
shell: fish
Tool kit management: brew (homebrew/linuxbrew)
- fish had installed
  - fish had set as default shell
- brew had installed
  - brew environment setting as official site
  - php had installed with brew
  - composer had installed with brew

target

I want to use PHP with "php" command which brew had installed but fail.

What I had done

I try to set environment by myself
- Following success in current shell but fail when restart shell
```
# in bash I tried these
PATH=${PATH}:/home/linuxbrew/.linuxbrew/bin/
export PATH=${PATH}:/home/linuxbrew/.linuxbrew/bin/

# in fish bash I tried these
set PATH $PATH /home/linuxbrew/.linuxbrew/bin/     <-update: updated
export PATH $PATH:/home/linuxbrew/.linuxbrew/bin/  <-update: wrong
```
- Following success in bash but fail in fish
  - add the command above in .bashrc file in user directory (.bashrc seems only run when bash)
- Following should success but fail
  - sudo -H vi /etc/environment
  - add /home/linuxbrew/.linuxbrew/bin/ in it

Solution

If you want commands to run when starting fish, you need to put them into a file called "config.fish" in ~/.config/fish/. Bashrc is, as the name implies, specific to bash.

Also "export" is used to mark a variable for "exporting", meaning passing it on to external commands the shell starts. $PATH is usually inherited from whatever starts the shell, which then means it's exported anyway, so your export line is useless.

Also your fish command needs a slight adjustment:

set PATH $PATH /home/linuxbrew/.linuxbrew/bin/

$PATH in fish is a list, and so it needs to be set as multiple arguments, not one string. In fish 3.0 (which was released after Ubuntu 18.04) this was adjusted to automatically split on ":", but even in that case you'll have to quote it or it will have surprising results.