How do I save IEx history?

With IEx (Elixir's REPL), I'd like to be able to save my command history.

For example:

I can open up a new IEx session and execute a command. After executing the command I can press the up arrow and have my last-command pre-populated. After closing IEx and re-opening, I'd like to have access to my last commands.

Is there a way to do this?

Solution

For Erlang/OTP 20

This is built-in (from https://hexdocs.pm/iex/IEx.html#module-shell-history)

From Erlang/OTP 20, it is possible to get shell history by passing some flags that enable it in the VM. This can be done on a per-need basis when starting IEx:

iex --erl "-kernel shell_history enabled"

If you would rather enable it on your system as a whole, you can use the ERL_AFLAGS environment variable and make sure that it is set accordingly on your terminal/shell configuration.

On Linux [and macOS]:

export ERL_AFLAGS="-kernel shell_history enabled"

On Windows:

set ERL_AFLAGS "-kernel shell_history enabled"

To show where the history file is located, run the following code from erl (Mac OS example value shown):

1> filename:basedir(user_cache, "erlang-history")
"/Users/your.username/Library/Caches/erlang-history"

To set the file to a different location, use the shell_history_path /path/to/history-file option from the erlang docs (compatible with Elixir/iex):

export ERL_AFLAGS="-kernel shell_history_path '\"$HOME/.erlang-history\"'"

For Erlang/OTP 19 and below

Try using https://github.com/ferd/erlang-history

> git clone https://github.com/ferd/erlang-history.git
> cd erlang-history
> sudo make install    # may not need sudo depending on installation