Why create a link like this: ln -nsf?

Question

What does this do?

ln -nsf

I know ln -s creates a symbolic link, not a hard link which means you can delete it and it won't delete the thing that it's linking to. But what do the other command arguments mean? (-nf)

Update: okay...so I remembered you can find this stuff out from the command line. Here's what I found out from typing ln --help:

-f, --force                 remove existing destination files
-n, --no-dereference        treat destination that is a symlink to a
                            directory as if it were a normal file

But this still isn't very clear to me what the implications of this are. Why would I want to create a soft/sym link like this?

Answer 1

From the BSD man page:

 -f    If the target file already exists, then unlink it so that the link
           may occur.  (The -f option overrides any previous -i options.)

 -n    If the target_file or target_dir is a symbolic link, do not follow
           it.  This is most useful with the -f option, to replace a symlink
           which may point to a directory.

Answer 2

the -n option (together with -f) forces ln to update a symbolic link to a directory. what does that mean?

suppose you have 2 directories

• foo
• bar

and an existing symbolic link

• baz -> bar

now you want to update baz to point to foo instead. if you just do

ln -sf foo baz

you would get

• baz/foo -> foo
• baz -> bar (unchanged), and thus
• bar/foo -> foo

if you add -n

ln -sfn foo baz

you get what you want.

• baz -> foo

that is what 'no-dereference' means: do not resolve an existing link and place the new link inside that directory, but rather just update it.

Answer 3

Here are all the options to ln. You'll find -n and -f in here.

 -F    If the target file already exists and is a directory, then remove
       it so that the link may occur.
       The -F option should be used with either -f or -i options.  If
       none is specified, -f is implied.
       The -F option is a no-op unless -s option is specified.

 -h    If the target_file or target_dir is a symbolic link, do not
       follow it.  This is most useful with the -f option, to replace 
       a symlink which may point to a directory.

 -f    If the target file already exists, then unlink it so that the
       link may occur.  (The -f option overrides any previous -i options.)

 -i    Cause ln to write a prompt to standard error if the target file
       exists.  If the response from the standard input begins with the
       character `y' or `Y', then unlink the target file so that the link
       may occur.  Otherwise, do not attempt the link.  (The -i option
       overrides any previous -f options.)

 -n    Same as -h, for compatibility with other ln implementations.

 -s    Create a symbolic link.

 -v    Cause ln to be verbose, showing files as they are processed.

Answer 4

You can type "man ln" to find such things:

   -f, --force
          remove existing destination files

   -n, --no-dereference
          treat destination that is a symlink to a directory as if it were
          a normal file

Answer 5

-f, --force remove existing destination files

-n, --no-dereference treat destination that is a symlink to a directory as if it were a normal file

Answer 6

-f says that if the target of your command is an existing file, it should be removed and replaced by the new link. (Note that in Unix-influenced systems, "file" can include directories, links, pipes, etc.)

-n modifies -f, saying that if the target you specify is an existing symbolic link, it should not be removed.