What does “+ 3” mean in result of ‘ls -al’?

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Accidentally, when moving to a mounted volume, and typing ll (alias for ls -laF)

:/media/username/DATA$ ll
total 153
drwxrwxrwx  1 username username  8192 Sep  1 20:32 ./
drwxr-x---+ 3 root     root      4096 Sep  3 08:14 ../
drwxrwxrwx  1 username username 12288 Jul 26 22:29 documents/
drwxrwxrwx  1 username username 16384 Sep  2 02:01 downloads/

I have this interesting part: drwxr-x---+ 3

I understand the part drwxr-x---, but what the else part + 3 means?

Ps: I’m using Ubuntu 16.04 x86

Answer

The + after the normal permission bits indicate a special permission is in effect for the file/directory. The special permission is POSIX ACL (Access Control List).

You can set a ACL rule by using setfacl and view the already set rule(s) by getfacl.

Example:

% ls -l foo.sh
-rwxrwxr-x 1 foobar foobar 206 Aug 28 02:08 foo.sh

% setfacl -m u:spamegg:x foo.sh

% ls -l foo.sh                
-rwxrwxr-x+ 1 foobar foobar 206 Aug 28 02:08 foo.sh

% getfacl foo.sh
# file: foo.sh
# owner: foobar
# group: foobar
user::rwx
user:spamegg:--x
group::rwx
mask::rwx
other::r-x

Check man getfacl and man setfacl to get more idea.

As a side note, if you see a . inplace of +, that’s for the SELINUX context.

And the 3 after + indicates number of hard links the file has. A hardlink is a name for the file (file’s inode precisely) so number of hard links indicate number of names the file has.

In your case the entry is:

drwxr-x---+ 3 root     root      4096 Sep  3 08:14 ../

It’s for the parent directory of the current directory (/media/username/DATA), so .. points to /media/username directory.

Now, in Linux, every directory has at least two hard links, one is for . (current directory, link to itself) and the other is it’s entry in the parent directory (name-inode mapping), this was inherited from the Unix.

You have hard link count as 3 for /media/username, which means /media/username has one subdirectory (default 2 plus one for the .. entry of the subdirectory). If there were 2 subdirectories, the hard link count would be 4 due to both subdirectories mapping .. back to the parent.

Check man ls also.

Attribution
Source : Link , Question Author : mja , Answer Author : heemayl

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