The rules for the patterns you can put in the .gitignore file are as follows:

• Blank lines or lines starting with # are ignored.

• Standard glob patterns work.

• You can end patterns with a forward slash (/) to specify a directory.

• You can negate a pattern by starting it with an exclamation point (!).

Glob patterns are like simplified regular expressions that shells use. An asterisk (*) matches zero or more characters; [abc] matches any character inside the brackets (in this case a, b, or c); a question mark (?) matches a single character; and brackets enclosing characters separated by a hyphen([0-9]) matches any character between them (in this case 0 through 9). You can also use two asterisks to match nested directories; a/**/zwould match a/z, a/b/z, a/b/c/z, and so on.

 

Here is another example .gitignore file:

# no .a files*.a# but do track lib.a, even though you're ignoring .a files above!lib.a# only ignore the root TODO file, not subdir/TODO/TODO# ignore all files in the build/ directorybuild/# ignore doc/notes.txt, but not doc/server/arch.txtdoc/*.txt# ignore all .txt files in the doc/ directorydoc/**/*.txt

GitHub maintains a fairly comprehensive list of good .gitignore file examples for dozens of projects and languages at  if you want a starting point for your project.