Erlang -- edlin

# edlin

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Module

edlin

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Module Summary

Line and input interpretter for the erlang shell.

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Since

Module edlin was introduced in OTP 26.1.

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Description

This module reads input, handles any escape sequences that have been configured via edlin_key and outputs action requests. The action requests are handled either by modules group or the user_drv.

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Key configuration

You can setup a custom key configuration that overrides the default key configuration. This is done by setting the stdlib application parameter shell_keymap before Erlang is started. If you want to have the same keymap in all Erlang shells you can do so by putting a config file in your user's home directory and then set ERL_FLAGS to load it at startup. For example:

    $ cat $HOME/.erlang_keymap.config
    [{stdlib,
      [{shell_keymap,
        #{ normal => #{ "\^[A" => clear } }
      }]
    }].
    $ ERL_FLAGS="-config $HOME/.erlang_keymap" erl

The current keymap configuration can be fetched through edlin:keymap(). If a custom keymap or keymap file is specified, then it will be merged with the default keymap.

The keymap is a map of maps where the keys in the parent map corresponds to different editing modes in the shell. The valid modes currently supported are normal and search.

The keys in the child maps are the escape sequences that are sent from the terminal when a key is pressed and each value is a valid action as seen below.

The default atom is used to specify that an action should happen when a key is pressed that does not have any mapping. Typically used to exit a mode.

See tty - A Command-Line Interface for more information about the default keymap.

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Actions

The commands below are the built-in action requests for switching input modes on the normal shell or navigating, or manipulating the line feed. The line feed supports multiple lines.

auto_blink

  Automatically close the closest matching opening parenthesis.

backward_char

  Move backward one character.

backward_delete_char

  Delete the character behind the cursor.

backward_delete_word

  Delete the word behind the cursor.

backward_kill_line

  Delete all characters from the cursor to the beginning of the line and save them in the kill buffer.

backward_kill_word

  Delete the word behind the cursor and save it in the kill buffer.

backward_line

  Move backward one line.

backward_word

  Move backward one word.

beginning_of_expression

  Move to the beginning of the expression.

beginning_of_line

  Move to the beginning of the line.

clear

  Clear the screen.

clear_line

  Clear the current expression.

end_of_expression

  Move to the end of the expression.

end_of_line

  Move to the end of the line.

forward_char

  Move forward one character.

forward_delete_char

  Delete the character under the cursor.

forward_line

  Move forward one line.

forward_word

  Move forward one word.

history_down

  Move to the next item in the history.

history_up

  Move to the previous item in the history.

kill_line

  Delete all characters from the cursor to the end of the line and save them in the kill buffer.

kill_word

  Delete the word under the cursor and save it in the kill buffer.

new_line_finish

  Add a newline at the end of the line and try to evaluate the current expression.

newline

  Add a newline at the cursor position.

open_editor

  Open the current line in an editor e.g. EDITOR="code -w" opens a buffer in vs code. Note that you need to pass a flag to the editor so that it signals the shell when you close the buffer.

redraw_line

  Redraw the current line.

search_cancel

  Cancel the current search.

search_found

  Accept the current search result and submit it.

search_quit

  Accept the current search result, but edit it before submitting.

search

  Enter search mode, search the history.

search_down

  Skip to the next line in the history that matches the current search expression.

search_up

  Skip to the previous line in the history that matches the current search expression.

tab_expand_full

  Output all possible tab completions.

tab_expand_quit

  Go back to normal mode.

tab_expand

  Autocomplete the current word, or show 5 lines of possible completions.

transpose_char

  Swap the character behind the cursor with the one in front of it.

transpose_word

  Swap the word behind the cursor with the one in front of it.

yank

  Insert the contents of the kill buffer at the cursor position.

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Data Types

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keymap() = #{atom() => #{string() | default => atom()}}

A map of maps for each shell mode containing key, action pairs.

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Exports

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keymap() -> keymap()
OTP 26.1

### Types

keymap() = #{atom() => #{string() | default => atom()}}

Get the current keymap used in the shell. Each key in the parent map represents a shell mode e.g. normal or search. Each map associated with the shell modes contains key sequences represented as strings, paired with an action, which is one of the valid actions mentioned above.