Bug #17283: Why does Dir.glob's ** match files in current directory?

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 2.7.2p137 (2020-10-01 revision 5445e04352) [x64-mingw32]
• Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN

[Yanir (Yanir Tsarimi)]

If my current directory has 1 file and 1 dir, and I use Dir.glob("**/*") or even just **, both the dir and the file would be matched.

I would expect that only the dir will be matched, since the glob starts with **, which wants to match a directory.
This is a behavior that's different from bash. In bash only the directory would be matched.

Ruby:

 Directory of C:\Users\User\z

10/24/2020  10:42 PM    <DIR>          .
10/24/2020  10:42 PM    <DIR>          ..
10/24/2020  10:42 PM    <DIR>          dir
10/24/2020  10:41 PM                 4 file
               1 File(s)              4 bytes
               3 Dir(s)  256,993,574,912 bytes free

C:\Users\User\z>irb
irb(main):001:0> Dir.glob("**/*")
=> ["dir", "file"]
irb(main):002:0> Dir.glob("**")
=> ["dir", "file"]

In Bash:

root@debian:~/rubytest# ls -lah
total 12K
drwxr-xr-x  3 root root 4.0K Oct 23 17:44 .
drwx------ 19 root root 4.0K Oct 23 17:43 ..
drwxr-xr-x  2 root root 4.0K Oct 23 17:44 dir
-rw-r--r--  1 root root    0 Oct 23 17:44 file
root@debian:~/rubytest# ls -lah **/*
-rw-r--r-- 1 root root 0 Oct 23 17:44 dir/subfile

I know the behavior is not meant to be 1:1 to bash. But this is still unexpected and doesn't make sense to me. Is this intended?

The documentation says:

**
Matches directories recursively.

[Eregon (Benoit Daloze)]

• Related to Bug #17280: Dir.glob with FNM_DOTMATCH matches ".." and "." and results in duplicated entries added

[Eregon (Benoit Daloze)]

Interestingly this behavior differs between Bash and Zsh:

$ tree
.
├── dir
│   └── subfile
└── foo

$ bash
$ echo **
dir foo
$ echo **/*
dir/subfile

$ zsh -f
$ echo **
dir foo
$ echo **/*
dir dir/subfile foo

I think we cannot change the behavior for compatibility.

As a fun fact, "**" can even match the parent directory with FNM_DOTMATCH (#17280).

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset git|e880d075f847ff17e1bc77301a9ed363fb40525b.

---

[DOC] refined "**" description in Dir.glob [ci skip]

As same as the description for File.fnmatch.
[Bug #17283]

[nobu (Nobuyoshi Nakada)]

Eregon (Benoit Daloze) wrote in #note-2:

Interestingly this behavior differs between Bash and Zsh:

Bash doesn't support **, and it just equals *.