I have tried to write mix task or even generate escript binary file, but it looks like that none of those ways supports some useful shell input methods. I tried to inspect arguments simply with IO.inspect(args)

here-document (<< operator)

A here document is a special-purpose code block. It uses a form of I/O redirection to feed a command list to an interactive program or a command, such as ftp, cat, or the ex text editor.

Source: https://www.tldp.org/LDP/abs/html/here-docs.html

What I have tried:

# Escript example:
$ ./example --test <<EOL
line 1
line 2
line 3
EOL
["--test"]

# Mix task example:
mix example.demo --test <<EOL
line 1
line 2
line 3
EOL
["--test"]

here-string (<<< operator)

A here string can be considered as a stripped-down form of a here document .
It consists of nothing more than COMMAND <<< $WORD ,
where $WORD is expanded and fed to the stdin of COMMAND .

Source: Here Strings

What I have tried:

# Escript example:
./example --test <<< 5*4
["--test"]

# Mix task example:
mix example.demo --test <<< 5*4
["--test"]

Maybe I need to compile Erlang with some extra flags or maybe it’s just not supported at all?