o is a small and fast text editor that is limited to the VT100 standard.

It's a good fit for writing git commit messages, using EDITOR=o git commit.

For a more feature complete editor that is also written in Go, check out micro.

You can install o with Go 1.10 or later:

go get -u github.com/xyproto/o

• Loads up instantly.
• Small executable size (around 500k, when built with gccgo and then stripped).
• Provides syntax highlighting for Go, C++ and Bash.
• Configuration-free, for better and for worse.
• Is limited to the VT100 standard, so hotkeys like ctrl-a and ctrl-e must be used instead of Home and End.
• Compiles with either go or gccgo.
• Tested with st, urxvt and xfce4-terminal.
• Tested on Arch Linux and FreeBSD.
• Loads faster than both vim and emacs.
• Never asks before saving or quitting. Be careful!
• Can format Go or C++ code, just press ctrl-space. This uses either goimports (go get golang.org/x/tools/cmd/goimports) or clang-format.
• Will strip trailing whitespace whenever it can.
• Must be given a filename at start.
• Smart indentation.
• Requires /dev/tty to be available.
• Copy, cut and paste is only for one line at a time. xclip must be installed if the system clipboard is to be used.
• May take a line number as the second argument, with an optional + prefix.
• The text will be red if a loaded file is read-only.
• The terminal needs to be resized to show the second half of lines that are longer than the terminal width.
• If the filename is COMMIT_EDITMSG, the look and feel will be adjusted for git commit messages.
• Supports UTF-8.
• Respects the NO_COLOR environment variable.
• Can render text to PDF.
• Only UNIX-style line endings are supported (\n).

• Files with lines longer than the terminal width are not handled gracefully.

When loading large files, an animated spinner will appear. The loading operation can be stopped at any time by pressing esc, q or ctrl-q.

• ctrl-q - Quit
• ctrl-s - Save
• ctrl-o - Format the current file using goimport or clang-format, depending on the file extension.
• ctrl-a - Go to start of line, then start of text on the same line, then the previous paragraph.
• ctrl-e - Go to end of line, then next paragraph.
• ctrl-p - Scroll up 10 lines
• ctrl-n - Scroll down 10 lines, or go to the next match if a search is active
• ctrl-k - Delete characters to the end of the line, then delete the line
• ctrl-g - Toggle a status line at the bottom for displaying: filename, line, column, unicode number and word count
• ctrl-d - Delete a single character
• ctrl-t - Toggle syntax highlighting
• ctrl-w - Toggle between "text" and "draw mode" (for ASCII graphics)
• ctrl-x - Cut the current line
• ctrl-c - Copy the current line
• ctrl-v - Paste the current line
• ctrl-b - Bookmark the current line
• ctrl-j - Jump to the bookmark
• ctrl-u - Undo (ctrl-z is also possible, but may background the application)
• ctrl-l - Jump to a specific line number
• ctrl-f - Search for a string.
• esc - Redraw the screen and clear the last search.
• ctrl-space - Build Go or C++ files, word-wrap other files.
• ctrl-\ - Toggle single-line comments
• ctrl-r - Render to a PDF document.

• The o executable is only 541k when built with GCC 9.2 (for 64-bit Linux).

• This isn't as small as e3, an editor written in assembly (which is 234k), but it's resonably lean.

  go build -gccgoflags '-Os -s'

It's around 3M when building with Go 1.13 and no particular build flags are given, which is also reasonable.

These four ways of opening file.txt at line 7 are supported:

• o file.txt 7
• o file.txt +7
• o file.txt:7
• o file.txt+7

This also means that filenames containing + or : are not supported, if followed by a number. Opening files with the c++ extension works, if you should want that.

If the very first keypress after starting o is O, G or /, it will trigger the following vi-compatible behavior:

• O - if followed by an uppercase letter, ignore the initial O
• / - enter search-mode (same as when pressing ctrl-f)
• G - go to the end of the file

The reason for adding these is to make using o easier to use for long-time vi/vim/neovim users.

• Version: 2.13.2
• License: 3-clause BSD
• Author: Alexander F. Rødseth <xyproto@archlinux.org>