ce

This is a curses-based editor written in Crystal that attempts to duplicate the functionality of my MicroEMACS variant. There is no good reason for me to create such a thing, since MicroEMACS is smaller, faster, and more portable. I'm doing it simply for my own amusement and education.

As of the time of this writing (2026-02-06), ce implements enough MicroEMACS functionality to perform basic editing, including undo, keyboard macros, and Ruby extensions. My hope is that the Crystal code will be easier to understand and modify than the C code in MicroEMACS.

Installation

Build ce using this command:

make

Then copy the resulting binary file ce to some place in your PATH.

ce requires no external shards (Crystal libraries). It does require the ncurses-dev or ncurses-devel packages for your Linux distro.

Usage

For the most part, you can use the MicroEMACS documentation as a guide for ce usage. But here are some notes about ce that might be helpful.

Missing Features

The following features from my MicroEMACS variant are missing in ce, but I may add them as needed:

• the ability to name macros or save them in text form
• profiles (loadable macros in text form)
• mark rings (I have never used this feature)
• line numbers
• frames (for multiple native windows)
• cscope support
• upper- and lower-case a region (I have never used this feature)
• incremental search (I have never used this feature)
• a few other little-used commands

Command Line

ce takes zero or more filenames as command line arguments. It will read all of the files, creating a buffer for each one. It will create as many windows for the files as will fit on the screen. You can still navigate to the buffers that don't have a window by using the F8 key.

You can append a line number reference of the form :line:column to each filename, telling ce to move the cursor to that point in the file. The line and column are 1-based, and the :column is optional. For example, this command will open the file src/buffer.cr and move to line 50, column 10:

ce src/buffer.cr:50:10

For compatibility with older programs such as cscope, you can also specify a line number by preceding a filename with a +line argument. For example, this command will open the file src/buffer.cr and move to line 50:

ce +50 src/buffer.cr

Commands

ce implements a large subset of MicroEMACS commands. See the section Key Bindings below for a complete list of commands. If you find yourself stuck while using ce, and don't have time to look at the Key Bindings section, here are the most useful key combos:

• F1: wait for a key, then display the command bound to that key
• Ctrl-X Ctrl-K: display all key bindings
• Ctrl-X Ctrl-S or F2: save current file
• Ctrl-X Ctrl-V or F3: open a file
• Ctrl-X Ctrl-C or F4: exit the editor
• Ctrl-X 2: split the window
• Ctrl-X N: move to the next window
• Ctrl-X 1: make the current window the only window
• F8: move to the next buffer
• F5: undo

Using Ctrl-G at any prompt will abort the entry.

Differences from MicroEMACS

The commands in ce perform nearly identically to those in MicroEMACS, but there are some minor differences:

• When the spell commands encounter a misspelled word, they pop up a window showing the suggested replacements. Then they prompt you to enter your own replacement, or type the number of one of the suggested replacements.

• Autocompletion for prompts: use the Tab key twice in a row (instead of the '?' key) to pop up a window showing the possible completions. Also, autocompletions for filenames automatically choose a file if there's only one choice, instead of waiting for you to confirm.

• The file-write command prompts you to confirm overwriting an existing file.

Ruby Extensions

ce supports Ruby extensions using the same RPC system that I implemented in MicroEMACS. For this to work, use sudo to copy ruby/server.rb from my MicroEMACS repository to the directory /usr/local/share/pe (create that directory if it does not exist). Then copy the desired Ruby extension from the ruby directory in my MicroEMACS repository to .pe.rb in your working directory.

Key Bindings

Here is a complete list of the key bindings in ce. C- indicates a Ctrl key combo; M- indicates an Esc key prefix; and C-X indicates a Ctrl X prefix.

Backspace        back-del-char
C-@              set-mark
C-A              goto-bol
C-B              back-char
C-D              forw-del-char
C-E              goto-eol
C-F              forw-char
C-G              abort
C-J              ruby-indent
C-K              kill-line
C-L              refresh
C-N              forw-line
C-O              ins-nl-and-backup
C-P              back-line
C-R              back-search
C-S              forw-search
C-T              twiddle
C-V              forw-page
C-W              kill-region
C-X (            start-macro
C-X )            end-macro
C-X +            balance-windows
C-X 1            only-window
C-X 2            split-window
C-X =            display-position
C-X B            use-buffer
C-X C-B          display-buffers
C-X C-C          quit
C-X C-K          display-bindings
C-X C-N          down-window
C-X C-P          up-window
C-X C-Q          toggle-readonly
C-X C-S          file-save
C-X C-V          file-visit
C-X C-W          file-write
C-X C-X          swap-dot-and-mark
C-X C-Z          shrink-window
C-X E            execute-macro
C-X G            goto-line
C-X I            spell-region
C-X N            forw-window
C-X P            back-window
C-X Return       echo
C-X U            undo
C-X X            xec
C-X Z            enlarge-window
C-Y              yank
C-Z              back-page
Del              forw-del-char
Down             forw-line
F1               help
F2               file-save
F3               file-visit
F4               quit
F5               undo
F6               ruby-string
F7               redo
F8               next-buffer
F9               search-again
Home             goto-bol
Kend             goto-eol
Left             back-char
M-!              reposition-window
M-$              spell-word
M-+              indent-region
M-/              reg-replace
M-<              goto-bob
M->              goto-eob
M-?              reg-query-replace
M-B              back-word
M-Backspace      back-del-word
M-C              cap-word
M-C-E            gccerr
M-C-F            fold-case
M-C-R            back-regexp-search
M-C-S            forw-regexp-search
M-D              forw-del-word
M-F              forw-word
M-I              set-save-tabs
M-J              fill-paragraph
M-L              lower-word
M-P              search-paren
M-Q              query-replace
M-R              replace-string
M-Tab            set-tab-size
M-U              upper-word
M-W              copy-region
M-X              extended-command
M-[              back-paragraph
M-]              forw-paragraph
M-{              back-paragraph
Pgdn             forw-page
Pgup             back-page
Return           ins-nl
Right            forw-char
Up               back-line