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5.1 Key Bindings

ne allows you to associate any keystroke with any command. To accomplish this task, you have to create a (possibly UTf-8) file named .keys in your ~/.ne directory. You can change the default name (possibly specifying a complete path) using the --keys argument (see Arguments).

The format of the file is very simple: each line starting with the ‘KEY’ sequence of capital characters is considered the description of a key binding. Each line starting with ‘SEQ’ binds a character sequence to a key. All other lines are considered comments. The format of a key binding description is

KEY hexcode command

The hexcode value is the ASCII code of the keystroke. (For special keys such as Insert or function keys, you should take a look at the file default.keys that comes with ne’s distribution: it contains a complete, commented definition of ne’s standard bindings that you can modify with a trial-and-error approach.) The easiest way to see the code ne uses for a given key is by using the KeyCode command. It prompts you to press a key, then reports the code for that key on the status bar. It also displays the command bound to that key if there is one.

You can write just the hexadecimal digits, nothing else is necessary (but a prefixing ‘0x’ is tolerated). For instance,

KEY 1 MoveSOL

binds to Control-A the action of moving to the start of a line, while

KEY 101 LineUp

binds to the “cursor-up” key the action of moving the cursor one line up.

command can be any ne command, including Escape (which allows reconfiguring the menu activator) and Macro, which allows binding complex sequences of actions to a single keystroke. The binding of a macro is very fast because on the first call the macro is cached in memory. See Macro.

Note that you cannot ever redefine Return or Escape. This is a basic issue—however brain damaged is the current configuration, you will always be able to exploit fully the menus and the command line.

Besides the “standard” combinations (e.g., Control-letter), it possible to program combinations based on the Meta key (a.k.a. Alt). The situation in this case is a bit more involved, because depending on the terminal emulator you are using, the effect of the Meta key can be widely different. For instance, xterm raises the eighth bit of a character, so, for instance,

KEY 81 MoveSOF

binds Control-Meta-a to the action of moving to the start of the document. However, gnome-terminal will emit the character of ASCII code 1 prefixed with ESC instead (“\x1b\x01”). To handle this case, ne provides codes from 180 on for simulated Meta sequences: for instance,

KEY 181 MoveSOF

binds the abovementioned sequence to the same action as before. In general, the code 180+x corresponds to the sequence ESC followed by the ASCII character of code x. Note that some of these sequences may be disabled, if they conflict with existing sequences of your terminal (for instance, ESC followed by ‘O’ is always disabled because it prefixes several built-in keyboard sequences).

As a final note, we remark that typing Meta-a on gnome-terminal will produce an ESC followed by ‘a’ (“\x1ba”). Since it is obviously easier to press just Meta rather than Meta and Control at the same time, it is a good idea to associate the same sequence also to this combination, using

KEY 1E1 MoveSOF

Moreover, this setting provides the user with a second choice: one can press Escape followed by a letter instead of using modifiers.

This is the approach used by default in ne: this way, Control with Meta plus a letter should always work, and Meta should work sometimes (of course, if you’re sure to use always the same kind of emulator you can bind more features). Again, the best place to look at it’s default.keys.

As stated above, each line starting with ‘SEQ’ binds a character sequence to a key code. The format for a ‘SEQ’ binding is

SEQ "sequence" hexcode

where "sequence" is a double-quoted string of characters (which can include escaped hexadecimals) followed by a hexadecimal key code as described above for ‘KEY’ definitions.

You should rarely need this, as properly configured systems already do this for most keys. However, some key combinations (Control in conjunction with cursor keys for example) are usually not defined. If you know the character sequence your system generates for such a combination, you may use ‘SEQ’ to bind that sequence to a particular key code if that sequence isn’t already defined on your system. For example, Control-“cursor-left” may generate the sequence \x1b[1;5D. The following lines bind that sequence to the f10 key code ‘14A’, then bind that key code to the ‘HELP’ command.

SEQ  "\x1b[1;5D"  14A
KEY  14A          HELP

Sequences are inherently terminal- or terminal emulator-specific, so their utility will vary depending on how many emulators you use. At least they give you the posibility to use keys or key combinations that aren’t covered by curses.

The key binding file is parsed at startup. If something does not work, ne exits displaying an error message. If you want ne to skip parsing the key binding file (for instance, to correct the broken file), just give ne the --no-config argument. See Arguments.


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