The PATH environment variable is read by the shell or libc to find and execute programs, this is how the shell can find /bin/ls when ls is typed in a terminal.

Shrink it

On Debian based desktop systems the default PATH variable look like this:

 
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

Much of this is not really necessary.

First, on modern systems, /{bin,sbin}/ directories are symlinks to /usr/{bin,sbin}/.

/usr/local has no use to me, if I compile/install software I'd rather they be put in the default locations¹.

Because sometimes I forgot to do ./configure --prefix=/usr before compiling, I have setup /usr/local to symlink to /usr (cd /usr && ln -s /usr local). For software that are not found in public repositories and that should run as a daemon I use /opt.

This leaves a much shorter PATH:

 
PATH=/usr/sbin:/usr/bin:/usr/games

To go further, I remove /usr/games since I run GUI programs (like games) through their .desktop entries. These entries are located at ${XDG_DATA_DIRS}/applications.

And as of the year 2024 that's it, I'll use the root symlinks to have a little bit shorter string:

 
PATH=/sbin:/bin

Eventually, /usr/sbin might merge into /usr/bin, so only /bin will be needed.

Expand it

Setting PATH in /etc/environment is not the entire picture.

Once the shell is loaded, it also reads /etc/profile and ~/.profile.

Modern programming environments, like Rust or Python, often add an entry to the PATH. However, I prefer to be explicit about what goes into the PATH, so I create symlinks:

 
$ file ~/bin ~/bin-rust ~/bin-py ~/bin-go ~/bin-js
~/bin:      directory
~/bin-rust: symbolic link to .cargo/bin
~/bin-py:   symbolic link to .local/bin
~/bin-go:   symbolic link to .golang/bin
~/bin-js:   symbolic link to .nvm/versions/node/v22.1.0/bin

I also want system binaries to take precedence on user one, so my .profile I make sure that $PATH comes first when reassigning:

 
# ...

# Hide default GOPATH
if [ -d "$HOME/.golang" ] ; then
    GOPATH="$HOME/.golang"
fi

# User's local bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$PATH:$HOME/bin"
fi

# RUST local bin if it exists
if [ -d "$HOME/bin-rust" ] ; then
    PATH="$PATH:$HOME/bin-rust"
fi

# Python local bin if it exists
if [ -d "$HOME/bin-py" ] ; then
    PATH="$PATH:$HOME/bin-py"
fi

# Golang local bin if it exists
if [ -d "$HOME/bin-go" ] ; then
    PATH="$PATH:$HOME/bin-go"
fi

# NodeJs local bin if it exists
if [ -d "$HOME/bin-js" ] ; then
    PATH="$PATH:$HOME/bin-js"
fi

export GOPATH
export PATH

With this setup, I can more easily verify if the correct binary is called.