I have seen colleagues using git add -A :/ for staging files in repositories, but I am unable to find what that does in the documentation. What am I missing?
Note: I understand what the flag -A does (this question has been answered in SO before). My question is specifically about :/ and the role it plays in git add.
As you already know the -A option, let's talk about git add :/ only. According to the documentation of git-add, the last argument is a pathspec. The definition of it is in the documentation of gitglossary. Let me quote the releant parts (I put the important sentences in bold):
A pathspec that begins with a colon : has special meaning. In the short form, the leading colon : is followed by zero or more "magic signature" letters (which optionally is terminated by another colon :), and the remainder is the pattern to match against the path. The optional colon that terminates the "magic signature" can be omitted if the pattern begins with a character that cannot be a "magic signature" and is not a colon.
In the long form, the leading colon : is followed by a open parenthesis (, a comma-separated list of zero or more "magic words", and a close parentheses ), and the remainder is the pattern to match against the path.
The "magic signature" consists of an ASCII symbol that is not alphanumeric.
top /
The magic word top (mnemonic: /) makes the pattern match from the root of the working tree, even when you are running the command from inside a subdirectory.
Currently only the slash / is recognized as the "magic signature", but it is envisioned that we will support more types of magic in later versions of git.
You can see that if a pathspec begins by :/ or :(top) then that part of the pathspec is by definition the root of the working tree.
git add :/ stages all files in the working tree.
(This answer originally talked about refspecs, which turned out to be irrelevant and incorrect.)
As lrineau's answer correctly points out, the : character in this case is part of the syntax of a pathspec.
Documentation on pathspecs is annoyingly difficult to find, but there's a "gitglossary" man page, available either by typing man gitglossary or visiting this web page.
The relevant part:
A pathspec that begins with a colon
:has special meaning. In the short form, the leading colon:is followed by zero or more "magic signature" letters (which optionally is terminated by another colon :), and the remainder is the pattern to match against the path. The optional colon that terminates the "magic signature" can be omitted if the pattern begins with a character that cannot be a "magic signature" and is not a colon.In the long form ... [snip].
The "magic signature" consists of an ASCII symbol that is not alphanumeric.
top /
The magic wordtop(mnemonic:/) makes the pattern match from the root of the working tree, even when you are running the command from inside a subdirectory.
The conclusion is the same as in my original answer: :/ refers to the root directory of the current working tree.
