The GNU Global source code tagging system is a utility that allows you to index all functions, global variable definitions, macros, etc… in a source code for easy navigation. The utility generates an index that can be used to easily locate the definition or references to a given symbol. The Gnu Global/Gtags system is very useful for hacking a large project containing many subdirectories. This article is a how-to guide for using Gtags with vim.

The Gtags binaries are available for most linux/unix distributions. To install Gtags in ubuntu/debian, type the following in the command line:

 sudo apt-get install global

To integrate Gtags functions with vim, we need to install the gtags vim plugin.

• Get the plugin from this page
• Place the file gtags.vim under ~/.vim/plugin/

After installing the plugin, it is a good idea to customize the way we use it from the vim interface for more convenience. This is an example of customized macros for Gtags (copy and paste to ~/.vimrc):

" Find definition of current symbol using Gtags
map <C-?> <esc>:Gtags -r <CR>

" Find references to current symbol using Gtags
map <C-F> <esc>:Gtags <CR>

" Go to previous file
map <C-p> <esc>:bp<CR>

After installing Gtags and integrating it with vim, we can start using it in a project. For this we need to :

• Go to the top directory of the project and type

    gtags .

• Set the environment variable GTAGSLIBPATH to point to the root directory of your project. You could alternatively set it as below if your source tree is at most 3 directories deep :

    export GTAGSLIBPATH=.:..:../..:../../..

• GNU Global Source code tagging system
• Gtags VIM plugin
• The VIM editor
• local copy of gtags.vim

Labels: coding