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Install Instructions

The pre-compiled binary for Linux works on a very wide range of distributions.

It should be possible to install it by running the following commands in your terminal:

# Move to your Desktop so you can see what is going on easier.
#
cd ~/Desktop/

# Download the 0.19.0 binary for Linux.
#
# +-----------+----------------------+
# | FLAG      | MEANING              |
# +-----------+----------------------+
# | -L        | follow redirects     |
# | -o elm.gz | name the file elm.gz |
# +-----------+----------------------+
#
curl -L -o elm.gz https://github.com/elm/compiler/releases/download/0.19.0/binary-for-linux-64-bit.gz

# There should now be a file named `elm.gz` on your Desktop.
#
# The downloaded file is compressed to make it faster to download.
# This next command decompresses it, replacing `elm.gz` with `elm`.
#
gunzip elm.gz

# There should now be a file named `elm` on your Desktop!
#
# Every file has "permissions" about whether it can be read, written, or executed.
# So before we use this file, we need to mark this file as executable:
#
chmod +x elm

# The `elm` file is now executable. That means running `~/Desktop/elm --help`
# should work. Saying `./elm --help` works the same.
#
# But we want to be able to say `elm --help` without specifying the full file
# path every time. We can do this by moving the `elm` binary to one of the
# directories listed in your `PATH` environment variable:
#
sudo mv elm /usr/local/bin/

# Now it should be possible to run the `elm` binary just by saying its name!
#
elm --help

Wait, what is the PATH variable?

When you run a command like elm make src/Main.elm, your computer starts by trying to find an executable file called elm.

The PATH is the list of directories that get searched. You can see these directories by running:

echo $PATH

This prints /usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin on my computer. The directories are separated by a : so there are five possibilities listed here.

When I run elm make src/Main.elm, my terminal starts by searching these five directories for an executable file named elm. It finds /usr/local/bin/elm and then runs /usr/local/bin/elm make src/Main.elm with whatever arguments I gave.

So the PATH environment variable is a convention that allows you to refer to a specific executable file without knowing exactly where it lives on your computer. This is actually how all "terminal commands" work! Commands like ls are really executable files that live in directories listed in your PATH variable.

So the point of running sudo mv elm /usr/local/bin/ is to turn the elm binary into a terminal command, allowing us to call it just like ls and cd.

Note: Why do we need to use sudo for that one command? Imagine if some program was able to add executables named ls or cd to /usr/local/bin that did something tricky and unexpected. That would be a security problem! Many distributions make this scenario less likely by requiring special permissions to modify the /usr/local/bin/ directory.


Uninstall

The following commands should remove everything:

# Remove the `elm` executable.
#
sudo rm /usr/local/bin/elm

# Remove any cached files. The files here reduce compile times when
# starting new projects and make it possible to work offline in more
# cases. No need to keep it around if you are uninstalling though!
#
rm -r ~/.elm/

If you have any Elm projects still on your computer, you can remove their elm-stuff/ directories as well.

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