The output of ls -l command yields the following result:

enter image description here

What is the number field between file permission and owner? i.e. what are those 1, 1, 1, and 2? I checked the --help but that doesn't explain it.

[EDIT] I thought it was the number of files in a directory but it isn't. See image. "tempFolder" has 3 files but still show a "2"


2 Answers 2


Note: edited after @StephaneChazelas comment

The first number of the ls -l output after the permission block is the number of hard links.

It is the same value as the one returned by the stat command in "Links".

This number is the hardlink count of the file, when referring to a file, or the number of contained directory entries, when referring to a directory.

A file typically has a hard link count of 1 but this changes if hard links are made with the ln command. See the Debian Reference manual.

In your example, adding a hard link for tempFile2 will increase its link count:

ln -l
ln tempFile2 tempHardLink
ln -l

Both tempFile2 and tempHardLink will have a link count of 2.

If you do the same exercise with a symbolic link (ln -s tempFile2 tempSymLink), the count value will not increase.

A directory will have a minimum count of 2 for '.' (link to itself) and for the entry in its parent's directory .

In your example, if you want to increase the link count of tempFolder, create a new directory and the number will go up.

ls -l tempFolder
mkdir tempFolder/anotherFolder
ls -l tempFolder

The link from anotherFolder/ to tempFolder/ (which is ..) will be added to the count.

  • 4
    See: unix.stackexchange.com/questions/31073/…
    – Mat
    Jul 14, 2012 at 12:24
  • 1
    Since it is displayed between the permissions and the ownership, you get the impression it very important, but I never used it. When is it typically needed? Jul 14, 2012 at 13:15
  • 4
    @EmanuelBerg when file systems were far less reliable than they are now and you were working on the file system you developed, and ls could spend 2 characters and give you more information, and there was no stat(1) command nor find(1) nor fsck, nor symlinks it was probably far more useful than it is today. It can't be changed without breaking shell scripts whose writers have long past into /dev/null; It has been that way since at least 1979.
    – msw
    May 12, 2013 at 11:31
  • May I know what its means for the dingdong.txt having value of 1 ? and what means if the value is 0 ? Sep 30, 2019 at 10:56

On Unix, typically, a file is some entry in a table of files. There are different sorts of files: regular files, devices, symbolic links, doors, pipes, sockets, directories...

The inode number (which you can see in the output of ls -i) is the index in that table.

Now, you don't access files by inode but by path. A path is a chain of directory entries. You'll notice we're not talking of folder but of directory here. Because it is what a directory is (think of a phone directory).

A directory is a special kind of file that gives names to a number of inodes. A directory entry is a mapping from a name to an inode.

A given file (an inode) can have more than one name in one directory (just like there can be more than one name at a phone number), and can also have names (entries) in more than one directory. Those are called links, also known as hard links to distinguish from soft links (a slang term for symbolic link, which is a special type of file which is a pointer to a path).

A file (inode) keeps track of the number of links (of entries in any directory) that it has, so that when the number reaches 0 (when it is being unlinked from the last directory it was referenced in), it is deallocated.

That's that number (the number of links) that is displayed in the ls -l output.

When a non-directory file is created the first time (with the open or creat (or bind or mknod for some types of files) system calls), it is done by providing a path to the new file (like "/a/b"). What happens then is a new file and inode is allocated and a new entry is added to the directory associated with the "a" name in the "/" root directory. That's the initial link so the link count is one.

More links can be added later on with the link() system call (the ln command). And links can be removed with the unlink() system call (the rm command).

You'll notice that the files of type directory generally have a number of links greater or equal to 2.

Now, when you create a directory, you're calling the mkdir() system call. Something like mkdir("/a/b"). What it does then is allocate a new file of type directory. In that new directory, it automatically creates two entries:

  • "." (dot for directory). Which is a link to itself. So the link count is now 1.
  • ".." (for directory's directory). Which is a link to "/a". So the link count of "/a" is incremented by one

Then that new directory is linked to "/a" (an entry is added in "/a" for it), so its link count is now 2. If a "/a/b/c" directory is created, because of the ".." entry in "/a/b/c", the link count of "/a/b" will become 3.

Most Unices restrict creating further links to a directory because they can cause problematic loops. When they do allow a link() on a directory, generally only the superuser can do it.

Some filesystems like btrfs depart from that traditional directory structure. You'll notice that link counts on directories in btrfs file systems are always one even though those directories do contain a "." entry with the same inode number as themselves in them.

The fact that the link count is traditionally 2 plus the number of subdirs has its use. For instance, in:

find . -name '*.c' -print

if . does not contain subdirs but contains millions of files. By checking the link count of ., find can know that there is no subdir. So all find has to do is read the content of the directory and report the entries that end in .c (like a grep '\.c$' on a few megabyte file, no big deal). Otherwise, find would have to check the type of every single file to see if there are directories to descend into in there (resulting in as many lstat() system calls). Of course, this kind of optimisation doesn't work on btrfs (though in modern versions of Linux, the type of files is also stored in the directory entry for some filesystems (including btrfs) and returned by the getdents(2) system call used to retrieve the list of entries in a directory, so lstat is still not necessary).

  • You compare a Unix directory to a telephone directory.  I guess that’s a valid comparison, but when I think “telephone directory”, I think of a book that’s bigger than just about any other book I’ve ever seen — bigger than any book I’ve seen in the past ten years — that lists all the people and businesses in a region of two or three counties.  A telephone directory might have over a million entries, and you probably wouldn’t have more than two or three of them in your house.  A telephone directory is, in some respects, more like the i-list than an individual directory. … (Cont’d) Sep 17, 2020 at 3:11
  • (Cont’d) … The phone tree at a company might be a better analogy.  The president might have a Rolodex listing the CEO, the COO, the CFO, the CIO, and nobody else.  The CEO might have a Rolodex listing the Director of Research and a few other people.  The CFO might have a Rolodex listing the Director of Marketing and a few other people.  If you wanted to talk to John Smith, who works on an assembly line or in a cubicle farm, you might (in principle) have to go through the president, the COO, the plant manager, the shift supervisor, and John’s immediate supervisor — in order to get John’s phone. Sep 17, 2020 at 3:11

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