Universal Ctags (abbreviated as u-ctags) is a maintained implementation of ctags. ctags generates an index (or tag) file of language objects found in source files for programming languages. This index makes it easy for text editors and other tools to locate the indexed items.

Exuberant Ctags (e-ctags) maintained by Darren Hiebert, the ancestor of Universal Ctags, improved traditional ctags with multi-language support, the ability for the user to define new languages searched by regular expressions (called optlib in Universal Ctags), and the ability to generate emacs-style TAGS files. But the activity of the project unfortunately stalled.

Universal Ctags has the objective of continuing the development of Exuberant Ctags. Reza Jelveh [email protected] initially created a personal fork of Exuberant Ctags on GitHub. As interest and participation grew, it was decided to move development to a dedicated project as Universal Ctags. The goal of this project is to maintain a common/unified working space where people interested in making ctags better can work together.

Some of the major features of Universal Ctags are:

• more numbers of improved language support
  • new extended C/C++ language parser, etc.
• fully extended optlib (a feature to define a new language parser from a command line)
• interactive mode (experimental)

If you want to try the latest Universal Ctags without building it yourself...

Daily builds are available at the ctags-win32 project. Go to the releases page to download zip packages.

Nightly builds are available at the ctags-nightly-build project. Go to the releases page to download tarball archives.

Recent builds are available via the universal-ctags Homebrew formula.

Go to ctags-snap and clone the ctags-snap repo. Then, follow instructions to build the snap package of Universal Ctags. Snapcraft will automatically fetch the source code from GitHub.

To build with Autotools (Autoconf and Automake) on GNU/Linux, OSX, or Windows 10 WSL,

    $ git clone https://github.com/universal-ctags/ctags.git
    $ cd ctags
    $ ./autogen.sh
    $ ./configure  # use --prefix=/where/you/want to override installation directory, defaults to /usr/local
    $ make
    $ make install # may require extra privileges depending on where to install

GNU make is assumed as the make command.

See docs/autotools.rst for more information.

To build on Windows, see docs/windows.rst for more information.

To build on OSX, see docs/osx.rst for more information.

The primary documents of Universal Ctags are man pages. Users should first consult the ctags(1), and other man pages if necessary.

Universal Ctags Hacking Guide, which also includes the man pages, is primarily for developers and provides additional information to the man pages, including experimental features.

See also */README.md on this repository.

You may be interested in how Universal Ctags is different from Exuberant Ctags. See ctags-incompatibilities(7) and Introduced changes for details.

The most significant incompatible changes:

• Universal Ctags doesn't load ~/.ctags and ./.ctags at starting up time. Instead, it loads ~/.ctags.d/*.ctags and ./.ctags.d/*.ctags.

• Universal Ctags is more strict about characters that can be used in kind letters and kind names than Exuberant-ctags.

  • The letter must be an alphabetical character ([a-zA-EG-Z]). F is reserved for file kind.

  • The first character of the name must be alphabetic, and the rest characters must be alphanumeric ([a-zA-Z][a-zA-Z0-9]*).

  The detailed background is explained in #1737.

  If you want to reuse your .ctags written for Exuberant-ctags, you must review kind letters and names defined with --regex-<LANG>=... options. When updating the definitions, using --kinddef-<LANG>=... option is appreciated.

It is not affected to Universal Ctags. It was fixed in e00c55d7a0204dc1d0ae316141323959e1e16162 in 2016. Thanks to the reporter.

Pull-requests are welcome!