$GIT_DIR/info/exclude, .gitignore
A gitignore file specifies intentionally untracked files that git should ignore. Note that all the gitignore files really concern only files that are not already tracked by git; in order to ignore uncommitted changes in already tracked files, please refer to the git update-index --assume-unchanged documentation.
Each line in a gitignore file specifies a pattern. When deciding whether to ignore a path, git normally checks gitignore patterns from multiple sources, with the following order of precedence, from highest to lowest (within one level of precedence, the last matching pattern decides the outcome):
Which file to place a pattern in depends on how the pattern is meant to be used. Patterns which should be version-controlled and distributed to other repositories via clone (i.e., files that all developers will want to ignore) should go into a .gitignore file. Patterns which are specific to a particular repository but which do not need to be shared with other related repositories (e.g., auxiliary files that live inside the repository but are specific to one user's workflow) should go into the $GIT_DIR/info/exclude file. Patterns which a user wants git to ignore in all situations (e.g., backup or temporary files generated by the user's editor of choice) generally go into a file specified by core.excludesfile in the user's ~/.gitconfig.
The underlying git plumbing tools, such as git ls-files and git read-tree, read gitignore patterns specified by command-line options, or from files specified by command-line options. Higher-level git tools, such as git status and git add, use patterns from the sources specified above.
Patterns have the following format:
An example:
$ git status [...] # Untracked files: [...] # Documentation/foo.html # Documentation/gitignore.html # file.o # lib.a # src/internal.o [...] $ cat .git/info/exclude # ignore objects and archives, anywhere in the tree. *.[oa] $ cat Documentation/.gitignore # ignore generated html files, *.html # except foo.html which is maintained by hand !foo.html $ git status [...] # Untracked files: [...] # Documentation/foo.html [...]
Another example:
$ cat .gitignore vmlinux* $ ls arch/foo/kernel/vm* arch/foo/kernel/vmlinux.lds.S $ echo '!/vmlinux*' >arch/foo/kernel/.gitignore
The second .gitignore prevents git from ignoring arch/foo/kernel/vmlinux.lds.S.
Documentation by David Greaves, Junio C Hamano, Josh Triplett, Frank Lichtenheld, and the git-list <m[blue]git@vger.kernel.orgm[][1]>.
Part of the git(1) suite