I find /* and * has different means when I compare with the setting:
*
!/init.el
!/README.md
!.gitignore
!/lib/
VS
/*
!/init.el
!/README.md
!.gitignore
!/lib/
The former not track /lib/ but the latter track it.
How to undertand * and /*?
UPDATE
I think this question is not exactly same as another one. Because he is focus on dir/** and dir/* but this one is focus on /* and *.
The first version ignores all files except those listed explicitly. lib is ignored because it contains no trackable files. Git does not track folders, so directories that appear empty seem to get ignored.
The second version ignores all root level files and directories except those listed explicitly. It does not ignore anything that is trackable and not in the root directory. lib is listed explicitly, so it is not ignored. Any files it contains are not at the root level, so they aren't ignored either.
The answer is a little complicated because Git's scanning algorithm is tricky, but it boils down to the fact that * matches lib/custom-file.el but /* does not.
As a general rule, in glob patterns, * does not "cross" path name separator /-es. Hence A*B matches ANameThatEndsInB but not ADirectory/WithAFileB.
Putting a / in a glob pattern requires that the thing before the / name a directory and the thing after the / occur within the directory: A*/*B does match ADirectory/WithAFileB. The name components, ADirectory and WithAFileB, are matched individually against the glob components, A* and *B.
A glob pattern ending in /, as in */, matches only directories. One starting with / has another special meaning in Git (but note that, e.g., the .gitignore entry /foo/bar/ consists of two components: /foo/ and then bar/; the bar/ part does not start with a slash). In particular, if the pattern starts with /, it applies only to files in the top level of that Git directory. If that's the top level .gitignore then this means the root of the work-tree itself.
Now, as in Mad Physicist's answer, it's true that if Git has no existing tracked files within a directory, Git does not have to read that directory sometimes. An ignore pattern that matches a directory name will make Git skip the scanning of the directory, if Git does not already have to scan that directory for some other reason. So in general, if you have a .gitignore that has * in it anywhere, any directory tends to get skipped entirely—well, as long as Git doesn't already have to look inside it for some other reason. So * in a .gitignore tends to ignore all directories. However, Git's ignore rules say that whenever Git has hold of a file or directory name and is checking .gitignore files, it should read through the entire file and find all matches, including the ones with ! in front of them. This means that, for instance:
*
!*/
will tell Git to ignore everything (including directories), but override that by saying don't ignore the */ directories. But the * will continue to ignore all files.
If you make it read:
/*
!/*/
you'll ignore all files in this directory (the one containing the .gitignore) but have Git scan all its subdirectories. Everything within any sub-directory such as foo/name will fail to match either of these glob patterns, since the foo/name part has a slash and the * cannot cross it.
