Understanding the usage of ln

From coreutils' manual, for ln

ln makes links between files. By default, it makes hard links; with
the -s option, it makes symbolic (or soft) links. Synopses:
ln [option]... [-T] target linkname
ln [option]... target
ln [option]... target... directory
ln [option]... -t directory target...
• If two file names are given, ln creates a link to the first file
from the second.

• If one target is given, ln creates a link to that file in the
current directory.

• If the –target-directory (-t) option is given, or failing that if
the last file is a directory and the –no-target-directory (-T) option
is not given, ln creates a link to each target file in the specified
directory, using the targets’ names.

What does the part in bold mean?

in particular
what do the followings mean

"failing that if the last file is a directory"
"using the targets’ names"?

Thanks.

Best Answer

It means that if you to ln /path/to/files/* /path/to/some/directory/ or ln -t /path/to/some/directory/ /path/to/files/*, a link to each of the files matching /path/to/files/* will be created in /path/to/some/directory/ with identical names to the originals.

Related Solutions

How to Create Symbolic Links with Wildcards in Linux

You might want to do that:

for dir in dir1 dir2
do
  [[ ! -d /somedir/$dir ]] && mkdir /somedir/$dir    
  find /media/sd*/$dir -type f -exec bash -c \
    '[[ ! -f /somedir/'$dir'/$(basename $1) ]] && ln -s $1 /somedir/'$dir'/' foo {} \;
done

This create symbolic links in /somedir/dir1/ (resp. dir2) pointing to all files present under /media/sd*/dir1 (resp. dir2). This script doesn't preserve hierarchy that might be present under the source directories.

Edit: Should you want all the links to be placed in a single directory, here is a slightly modified version:

[[ ! -d /somedir/data ]] && mkdir /somedir/data    
find /media/sd*/dir[12] -type f -exec bash -c \
    '[[ ! -f /somedir/data/$(basename $1) ]] && ln -s $1 /somedir/data/' foo {} \;
done

Linux – How to Change Ownership of Symbolic Links

On a Linux system, when changing the ownership of a symbolic link using chown, by default it changes the target of the symbolic link (ie, whatever the symbolic link is pointing to).

If you'd like to change ownership of the link itself, you need to use the -h option to chown:

-h, --no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the ownership of a symlink)

For example:

$ touch test
$ ls -l test*
-rw-r--r-- 1 mj   mj   0 Jul 27 08:47 test
$ sudo ln -s test test1
$ ls -l test*
-rw-r--r-- 1 mj   mj   0 Jul 27 08:47 test
lrwxrwxrwx 1 root root 4 Jul 27 08:47 test1 -> test
$ sudo chown root:root test1
$ ls -l test*
-rw-r--r-- 1 root root 0 Jul 27 08:47 test
lrwxrwxrwx 1 root root 4 Jul 27 08:47 test1 -> test

Note that the target of the link is now owned by root.

$ sudo chown mj:mj test1
$ ls -l test*
-rw-r--r-- 1 mj   mj   0 Jul 27 08:47 test
lrwxrwxrwx 1 root root 4 Jul 27 08:47 test1 -> test

And again, the link test1 is still owned by root, even though test has changed.

$ sudo chown -h mj:mj test1
$ ls -l test*
-rw-r--r-- 1 mj mj 0 Jul 27 08:47 test
lrwxrwxrwx 1 mj mj 4 Jul 27 08:47 test1 -> test

And finally we change the ownership of the link using the -h option.

Best Answer

Related Solutions

How to Create Symbolic Links with Wildcards in Linux

Linux – How to Change Ownership of Symbolic Links

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