Usage: ln [OPTION]... [-T] TARGET LINK_NAME
or: ln [OPTION]... TARGET
or: ln [OPTION]... TARGET... DIRECTORY
or: ln [OPTION]... -t DIRECTORY TARGET...
In the 1st form, create a link to TARGET with the name LINK_NAME.
In the 2nd form, create a link to TARGET in the current directory.
In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.
Create hard links by default, symbolic links with --symbolic.
By default, each destination (name of new link) should not already exist.
When creating hard links, each TARGET must exist. Symbolic links
can hold arbitrary text; if later resolved, a relative link is
interpreted in relation to its parent directory.
Mandatory arguments to long options are mandatory for short options too.
--backup[=CONTROL] make a backup of each existing destination file
-b like --backup but does not accept an argument
-d, -F, --directory allow the superuser to attempt to hard link
directories (note: will probably fail due to
system restrictions, even for the superuser)
-f, --force remove existing destination files
-i, --interactive prompt whether to remove destinations
-L, --logical dereference TARGETs that are symbolic links
-n, --no-dereference treat LINK_NAME as a normal file if
it is a symbolic link to a directory
-P, --physical make hard links directly to symbolic links
-r, --relative create symbolic links relative to link location
-s, --symbolic make symbolic links instead of hard links
-S, --suffix=SUFFIX override the usual backup suffix
-t, --target-directory=DIRECTORY specify the DIRECTORY in which to create
-T, --no-target-directory treat LINK_NAME as a normal file always
-v, --verbose print name of each linked file
--help display this help and exit
--version output version information and exit
The backup suffix is '~', unless set with --suffix or SIMPLE_BACKUP_SUFFIX.
The version control method may be selected via the --backup option or through
the VERSION_CONTROL environment variable. Here are the values:
none, off never make backups (even if --backup is given)
numbered, t make numbered backups
existing, nil numbered if numbered backups exist, simple otherwise
simple, never always make simple backups
Using -s ignores -L and -P. Otherwise, the last option specified controls
behavior when a TARGET is a symbolic link, defaulting to -P.
GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Full documentation at: <https://www.gnu.org/software/coreutils/ln>
or available locally via: info '(coreutils) ln invocation'
Symbolic links are essentially shortcuts that reference to a file instead of its inode value. This method can be applied to directories and can reference across different hard disks/volumes. Since the symbolic link is referring to the original file and not its inode value, then replacing the original file into a different folder will break the symbolic link, or create a dangling link.
$ cat file1
$ ln -s file1 sym-link-test
$ cat sym-link-test
$ ll sym-link-test
lrwxrwxrwx 1 johndo johndo 5 Mar 17 11:47 sym-link-test -> file1
A hard link is a direct reference to a file via its inode. You can also only hardlink files and not directories. By using a hardlink, you can change the original file’s contents or location and the hardlink will still point to the original file because its inode is still pointing to that file. There is no referencing to the original file. In addition, hardlinks can only refer to files within the same volume otherwise symbolic links will be needed.
$ cat file1
$ ln file1 hardlink-test
$ cat hardlink-test
$ ll hardlink-test
-rw-rw-r-- 2 b b 10 Mar 17 11:39 hardlink-test