Where to find info about `iex -S mix` command?

I was playing around with different ways of running my Elixir code from file and noticed that I cannot find any info regarding the iex -S mix command.
Can someone point me to a link or a way of getting that info from iex help directly?

iex accepts the same options as elixir, + some…
You can get them with

$ iex --help
$ elixir --help
Usage: elixir [options] [.exs file] [data]

## General options

  -e "COMMAND"                 Evaluates the given command (*)
  -h, --help                   Prints this message (standalone)
  -r "FILE"                    Requires the given files/patterns (*)
  -S SCRIPT                    Finds and executes the given script in $PATH
  -pr "FILE"                   Requires the given files/patterns in parallel (*)
  -pa "PATH"                   Prepends the given path to Erlang code path (*)
  -pz "PATH"                   Appends the given path to Erlang code path (*)
  -v, --version                Prints Erlang/OTP and Elixir versions (standalone)

  --app APP                    Starts the given app and its dependencies (*)
  --erl "SWITCHES"             Switches to be passed down to Erlang (*)
  --eval "COMMAND"             Evaluates the given command, same as -e (*)
  --logger-otp-reports BOOL    Enables or disables OTP reporting
  --logger-sasl-reports BOOL   Enables or disables SASL reporting
  --no-halt                    Does not halt the Erlang VM after execution
  --short-version              Prints Elixir version (standalone)
  --werl                       Uses Erlang's Windows shell GUI (Windows only)

Options given after the .exs file or -- are passed down to the executed code.
Options can be passed to the Erlang runtime using $ELIXIR_ERL_OPTIONS or --erl.

## Distribution options

The following options are related to node distribution.

  --cookie COOKIE              Sets a cookie for this distributed node
  --hidden                     Makes a hidden node
  --name NAME                  Makes and assigns a name to the distributed node
  --rpc-eval NODE "COMMAND"    Evaluates the given command on the given remote node (*)
  --sname NAME                 Makes and assigns a short name to the distributed node

## Release options

The following options are generally used under releases.

  --boot "FILE"                Uses the given FILE.boot to start the system
  --boot-var VAR "VALUE"       Makes $VAR available as VALUE to FILE.boot (*)
  --erl-config "FILE"          Loads configuration in FILE.config written in Erlang (*)
  --pipe-to "PIPEDIR" "LOGDIR" Starts the Erlang VM as a named PIPEDIR and LOGDIR
  --vm-args "FILE"             Passes the contents in file as arguments to the VM

--pipe-to starts Elixir detached from console (Unix-like only).
It will attempt to create PIPEDIR and LOGDIR if they don't exist.
See run_erl to learn more. To reattach, run: to_erl PIPEDIR.

** Options marked with (*) can be given more than once.
** Standalone options can't be combined with other options.

and also

$ mix --help
$ iex --help

It accepts all other options listed by "elixir --help".
$ elixir --help
## General options
  -S SCRIPT                    Finds and executes the given script in $PATH

So you know that it’s running a mix is a script which is in your $PATH.

Inspecting the script reveals it to be this:

So, iex -S mix starts iex, and runs the mix script which starts Mix and sets it up for interactive operations.

Good question though, I’m not sure if there are any docs that actually explain iex -S mix beyond “run this to start your mix project in iex”.


I found the commit where iex -S mix was introduced, which explains some of the history: