Textern

Textern is a Firefox add-on that allows you to edit text areas in web pages using an external editor. It is similar in functionality to the popular It's All Text! add-on, though makes use of the WebExtension API and is thus fully compatible with multiprocessing and planned to be supported beyond Firefox 57.

The add-on is divided into two parts:

the WebExtension, which is available from AMO here, and
the native application, which handles text editor launching and monitoring.

The native application currently only supports Linux with Python 3.5. Patches to add support for other platforms are welcome!

Installation

To clone the repository:

$ git clone --recurse-submodules https://github.com/jlebon/textern
$ cd textern

IMPORTANT: make sure that your git checkout includes submodules (either use the --recurse-submodules when running git clone as shown above, or use git submodule update --init if already cloned).

To install the native app, run:

$ sudo make native-install

To uninstall it, run:

$ sudo make native-uninstall

On distros which do not use /usr/lib64 (such as Debian/Ubuntu), you'll want to override LIBDIR:

$ sudo make native-install LIBDIR=/usr/lib

If you do not have root privileges or wish to only install the native app for the current user, run:

$ make native-install USER=1

Usage

Once both the WebExtension and the native application are installed, you can select any textbox and press Ctrl+Shift+D to open an external editor. The textarea will flash yellow upon launching the text editor, as well as whenever the file is saved.

By default, gedit is opened. You can change both the key mapping as well as the configured editor in the addon preferences. Additional parameters may be passed to the editor. For example:

["myeditor", "--custom-arg"]

will launch myeditor --custom-arg /path/to/file.txt. You may use %s as a variable for the file path if don't want it to be the last argument.

If your editor supports it, you can also use %l and %c to pass the line and column number of the caret position. (The capitalized versions %L and %C also exist which are smaller by one for text editors that count from zero). For example, passing this information to gvim (or vim):

["gvim", "-f", "+call cursor(%l,%c)"]

Terminal editors

If you would like to use a terminal editor such as vim or emacs, you will need to modify the configuration such that Textern starts a terminal emulator which runs the text editor. For example, for nvim this could look like

["xterm", "-e", "nvim", "+call cursor(%l,%c)"]

Here, xterm is the terminal emulator, -e instructs it to start a program, which is nvim (the editor we're actually interested in) with the given parameters.

This works similarly with konsole or gnome-terminal instead of xterm. For example, starting vim with gnome-terminal:

["gnome-terminal", "--wait", "--", "vim", "+call cursor(%l,%c)"]

Note that by default the gnome-terminal process won't wait for the spawned process to finish before exiting so you'll need to make sure you add the --wait flag.

GUI editors

Non-terminal-based editors can also suffer from the same waiting problem described above. For example, gedit does not fork and thus can be used directly:

["gedit"]

On the other hand, gvim by default will fork and detach. One must thus make sure to pass the -f switch for it to stay in the foreground:

["gvim", "-f"]

Flatpak

Flatpak-packaged editors should work fine, as long as the application has access to the XDG_RUNTIME_DIR directory. For example, to use the GNOME gedit flatpak, use:

["flatpak", "run", "--filesystem=xdg-run/textern", "org.gnome.gedit"]

Troubleshooting

Some things to try if it doesn't work properly:

Ensure you are running the latest version of Firefox
Try configuring Textern to launch using a different shortcut
Try configuring Textern to use the following as the external editor: ["sh", "-c", "echo foobar > $0"] (that should just echo foobar into the textarea box)
Check the browser console for errors (Ctrl+Shift+J)
Check the extension's console for errors (Go to about:debugging, find Textern in the list of extensions, and click Inspect)
Make sure you cloned the repo with --recurse-submodules (see installation instructions above)
Try re-installing but for your local user (make native-install USER=1 instead of sudo make native-install)
Check if Textern is running in the background (ps aux | grep textern)

Firejail

Firejail is a sandboxing program to restrict what your browser can do. It will prevent Textern from working.

If you install Textern with USER=1, and your firejail instance is not using apparmor, then add to /etc/firejail/firejail.local:

whitelist ${HOME}/.local/libexec/textern/
noblacklist ${PATH}/python3*
noblacklist /usr/lib/python3*

If apparmor is enabled, then add the Python lines to firejail.local and see issue 52.

Related Projects

It's All Text!

https://github.com/docwhat/itsalltext/

This is the project that inspired this add-on. Unfortunately, it is not compatible with WebExtensions and thus cannot be installed on Firefox 57 or later.

Tridactyl

https://github.com/cmcaine/tridactyl

Generic addon that adds Vim-like bindings to Firefox, including an :editor command which provides similar functionality to Textern.

withExEditor

https://github.com/asamuzaK/withExEditor

Similar to Textern and supports WebExtensions. Native app is cross-platform but requires Node.js.

GhostText

https://github.com/GhostText/GhostText

Uses editor-specific plugins to provide two-way on-the-fly sync between webpage and editor.

fidergo-stephane-gourichon/textern