Git Not Ignoring Sub-Directories

Question

I had static/ in the .gitignore, which successfully ignored the entire directory. I now want to stage everything in it except static/vendor.

I thought that having static/vendor/ inside .gitignore would do it. However, it does not. When I submit static for staging, all files from inside static/vendor still end up being staged alongside others that I actually want.

Is there a trick to this? What am I missing?

Answer 1

The .gitignore rules are a little weird. (For that matter, the name .gitignore is a little weird, but forgivable: a better name would be .git-do-not-complain-about-some-files-that-are-untracked-and-do-not-automatically-add-them-in-that-case-but-this-file-has-no-effect-on-files-that-are-tracked, or something equally unweildy.)

Each line in .gitignore has one of a few general forms:

• comments and blank lines get ignored;
• lines with ! are do-not-ignore rules; and
• the remaining lines are ignore-rules.

This lets us dispense with the first type entirely, and think about the second and third type of line using one set of rules, with the "do not ignore" applied at the end. So now we're down to the following sub-rules:

• lines can contain a name with no slash at all: foo, or
• lines can contain a file name with a leading slash, but no embedded slash: /leading, or
• lines can contain a file name with a trailing slash, but no embedded slash: trailing/, or
• lines can contain a file name with leading and trailing slash, but no embedded slash: /leadandtrail/, or
• lines can contain a file name that does have an embedded slash, combined with any or all of the above: has/slash, /has/slash, has/slash/, and so on.

(Lines can also contain various glob characters, which for now, let's not worry about!)

To keep this explosion of sub-categories simpler, we want to group them into just two crucial sub-categories, which I will call anchored and un-anchored. Along a separate axis, we want to group them into two other crucial sub-categories, which I will call slash-suffixed and not-slash-suffixed.

An anchored name is any name that either starts with a slash or contains an embedded slash (or both). So /leading and has/slash and /has/slash are all anchored, but foo and trailing/ are un-anchored.

A slash-suffixed name is any name that ends in slash. This one final slash is removed as soon as the name is categorized as slash-suffixed. So trailing/ is slash-suffixed but then treated as if it were just spelled trailing, and has/slash/ is also slash-suffixed and treated as if it were just spelled has/slash.

Hence the entry:

vendor/

is slash-suffixed but un-anchored, while:

static/vendor/

is both slash-suffixed and anchored.

(A name like a/b// is slash-suffixed and anchored and treated like a/b/, and a name like b// is slash-suffixed and anchored and treated like b/. The extra slash left over is just a bad idea: don't do it. I'm not sure what actually happens!)

Now that we've categorized the names as anchored or un-anchored and slash-suffixed or not-slash-suffixed, we can describe how the gitignore rules work for them:

• Any slash-suffixed name matches a partial path name if and only if that partial path name represents a directory/folder. So vendor/ matches the directory (or folder) vendor, but not a file whose name component is vendor. Without the slash-suffix, the name matches both a file and a directory.

• Any anchored name matches only the components of file name that start from the same directory in which the .gitignore file was found. That is, given an anchored vendor, we'll exclude vendor in this directory, but not a/vendor, b/vendor, and so on. Given an unanchored vendor, we'll exclude vendor in this directory and a/vendor and b/vendor and so on.

This is why adding static/ in front of your vendor/ changed its behavior: it went from un-anchored to anchored, so that it began to act like /static/vendor/ (which would of course do the same thing: it's anchored in two ways, but the only thing that matters is that it is anchored).

Adding **/ in front enables the (still-anchored!) string static/vendor/ to match a/static/vendor, b/static/vendor, and so on. You didn't need the **/ in front when vendor/ was un-anchored.

An alternative

Note, by the way, that you could remove the vendor/ entry entirely from this .gitignore file (wherever it is) and create a static/ entry in vendor/.gitignore, creating that file if necessary. That would be un-anchored but slash-suffixed. It would match the directory static in that directory or any sub-directory of that directory. Edit: Oops, this was backwards: you would want a vendor/ in the static/ directory. But the general principle applies here.

(The main, or perhaps only, drawback to this is that you will have created or altered a file in this particular sub-directory—and, of course, that you might need to do it in multiple sub-directories.)