howl.util.ignore_file provides support for “ignore files”, more specifically Git ignore files (e.g. .gitignore) and the ignore files used by searchers such as ripgrep and The Silver Searcher (i.e. .ignore). The purpose of ignore files is ignore certain files or directories within a target directory. This is accomplished by having one or more ignore files in the target directory, either at the root or in any arbitrary sub directory, containing patterns which specify what to ignore. You can read more about ignore files in the manpage for gitignore.

This module has been written to handle all of the known cases for ignore files at the time of this writing. This includes negations, escapes, all different types of globs, correct handling of sub directory ignore files, etc. Any missing functionality should thus be considered a bug, so please report any detected omissions.

General usage

You can create an ignore matcher using one of two possible ways (see below), but for both scenarios you’ll get back a callable object that works within the context of a certain directory. These callable objects you can invoke with paths relative to the context directory, and the return value will indicate whether the path should be ignored (true for ignore, and false for allowing it).

The relative paths passed are assumed to have a trailing slash for directory entries.


evaluator (dir, opts = {})

This creates an ignore matcher for the specified dir, which will take into account any parent ignore files as well as any relevant ignore files in sub directories. By default the evaluator will consult both .gitignore and .ignore files (giving precedence to the latter), but this can be controlled by specifying ignore_files in opts. The most important file should be specified first (default values is {'.ignore', '.gitignore'}).


Given a directory /tmp/foo and the following ignore files:







The following snippet shows the expected results:

dir ='/tmp/root')
ignore = howl.util.ignore_file.evaluator dir
ignore 'obj.o' -- => true (from parent ignore file)
ignore 'bar' -- => true (from parent ignore file)
ignore 'zed' -- => true (from root file)
ignore 'sub/sandwich' -- => true (from root ignore file)
ignore 'sub/my.o' -- => false (overriden from sub ignore file)
ignore 'sub/frob' -- => true (from sub ignore file)
ignore 'frob' -- => false (ignored only in sub directory)

ignore_file(file, dir)

Invoking the module directly for a given file returns a matcher for the specified file only. No parent or sub directory ignore files will be consulted, only file. If dir is specified then the matching will be done in the context of that directory - otherwise the file’s parent directory will be used as the context.