Git of the day #10: git add :/path/to/file

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When providing paths to git add, the path is relative to the current directory, or absolute prefixed with / like any other command that takes a path. There are additional forms of paths to provide to various Git commands, such as git-add, one of which is to prefix the path with a colon.

Using a colon at the beginning of a path makes the path relative to the root of the repo, regardless of what the current directory is.

There's two great uses of this:

• Adding a specific path to a known file when cd'd deep into a repo. For example, when working on a Go repo and cd'd into a package deep in the hierarchy, but needing to add a change to go.mod in the module root made by go get, one can git add :/go.mod rather than needing the right number of ../../ prefixes.
• Adding all files in the working copy. git add . would only add the current directory which may be a subdirectory of the repository if that is the current directory, but git add :/ would add all.

Git commands that take a path call the path a ‘pathspec’. A pathspec has additional capability over a regular path other commands may take on the command line — this colon behaviour being one of them, and the colon opens additional behaviour under it, such as / for the root of the repo. / is actually shorthand for (top), so git add :(top)go.mod is equivalent to git add :/go.mod. Here are my favourite pathspec-colon behaviours:

• :/ or :(top) for adding paths from the root of the repo
• :(literal) for adding paths that include glob characters, * and ?, literally rather than as wildcards
• :(icase) for case insensitive path matching.

This makes pathspec more powerful for matching files, and easier to use in repositories with deep hierarchy.