Modes

sled has four modes of operation.

Insert mode

The initial mode which is active on startup. It behaves like one would expect from a “normal” text editor: most characters are self-inserting, arrow keys and Backspace/Delete work as expected, and so on.

Command mode

Command mode behaves more like vi(1): characters like h, j, k, l no longer insert themselves but execute commands (in this case movement commands).

Overwrite mode

This is the same as insert mode, except that newly inserted characters replace the existing ones instead of being inserted among them.

Selection mode

In this mode, moving around the file extends the selection, and most commands that alter text instead delete the selection and exit selection mode.

sled additionally has three “modal modes”, which are active as long a modal dialog is shown on screen. They are: help mode, input mode and numerical input mode.

Global key bindings

These are active in all modes, and are as follows:

Insert and overwrite mode key bindings

In Insert mode and Overwrite mode, characters are self-inserting, and Enter inserts new line. All the global keys apply to insert mode as well. Entering overwrite mode switches back to insert mode when the overwrite mode is toggled off, even when the overwrite mode was entered from the command mode.

Command mode key bindings

In Command mode, the following vi-like keys are in effect:

Selection mode key bindings

If Selection mode was entered from insert mode (or insert mode is activated during selection mode), typing any self-inserting character or activating key bindings which modify text, like Delete or C-K, will erase the selected text instead, and in the case of self-inserting characters, insert the character in question, exiting the selection mode.

Similar holds true when the selection mode is entered from the command mode or the command mode is activated during the selection mode, except that vi-like key bindings which modify text will have the effect on the selection.

Status line

Status line is comprised of a number of segments, by default four.

• The leftmost segment displays the current filename, with an asterisk (*) if there are any unsaved changes.
• Second segment displays the current mode.
• Third segment displays the Unicode codepoint at the position of the cursor.
• Fourth segment displays the current position within the file, in the form
  [column]:[row] ([percentage of total lines]%)
• Fifth segment shows quick help.

Known limitations

• UTF-8 character set is assumed.
• RTL scripts are unsupported/problematic. CJK scripts should work better after v0.17, which introduced the use of wcwidth(3).
• Only one file can be edited at a time, and no additional files can be loaded at runtime. This is a design decision.
• If backup creation is enabled (create_backups in config.h), the directory of the edited file must be writable by the user to open the file.
• Opening binary files (containing NUL bytes) can lead to an incorrectly drawn display. This was the reason for introducing the option open_binary, by default set to zero.