Symlink not updating as expected when using an absolute with relative path
I am trying to use symbolic links. I did some reading and found the following commands:
Creation -> ln -s {/path/to/file-name} {link-name}
Update -> ln -sfn {/path/to/file-name} {link-name}
Deletion -> rm {link-name}
Creations and deletions work fine. But updates do not work. After performing this command, the symlink becomes invalid.
I have read here and there that it is not possible to update/override a symlink. So there is contradictory information on the net. Who is right? If a symlink can be updated/overridden, how can I achieve this?
Update
Here is my directory structure:
~/scripts/test/
~/scripts/test/remote_loc/
~/scripts/test/remote_loc/site1/
~/scripts/test/remote_loc/site1/stuff1.txt
~/scripts/test/remote_loc/site2/
~/scripts/test/remote_loc/site2/stuff2.txt
~/scripts/test/remote_loc/site2/
~/scripts/test/remote_loc/site3/stuff3.txt
From ~/scripts/test/, when I perform:
ln -s /remote_loc/site1 test_link
a test_link is created, and I can ls -l it, but it seems broken (contrary to what I said above in my question).
How can I perform a multiple directory level link?
Using -f with ln will overwrite any link that was already there, so as long as you have the correct permissions, it should work... It's always worked for me. What operating system are you using?
Ok, I found where my error is: one should not put the first / in path.
In other words, the commands in my questions should be:
Creation -> ln -s {path/to/file-name} {link-name}
Update -> ln -sfn {path/to/file-name} {link-name}
instead of
Creation -> ln -s {/path/to/file-name} {link-name}
Update -> ln -sfn {/path/to/file-name} {link-name}
considering my case.
First issue:
Quoting you:
Creations and deletions work fine. But updates do not work. After performing this command, the symlink becomes invalid.
The problem With the given directory structure:
~/scripts/test/ ~/scripts/test/remote_loc/ ~/scripts/test/remote_loc/site1/ ~/scripts/test/remote_loc/site1/stuff1.txt ~/scripts/test/remote_loc/site2/ ~/scripts/test/remote_loc/site2/stuff2.txt ~/scripts/test/remote_loc/site2/ ~/scripts/test/remote_loc/site3/stuff3.txt
and using the command:
ln -s /remote_loc/site1 test_link
Is that it creates a symbolic link in your $PWD, or present working directory, that points to a non-existing file off the /, or root, at /remote_loc/site1
If your PWD is in ~/scripts/ then you should have used this:
ln -s remote_loc/site1 test_link
else you could have used the full absolute path like:
ln -s /home/yourusername/remote_loc/site1 test_link
Second issue:
Quoting you:
I have read here and there that it is not possible to update/override a symlink. So there is contradictory information on the net. Who is right? If a symlink can be updated/overridden, how can I achieve this?
To answering your question "Who is right", I am not sure what exactly you read, or how it was understood. But, the following should help clear up:
- What can be updated, and
- What can not be updated without using appropriate switches.
Updating symbolic links with targets that are not directories.
ln -sf:
The -f or --force remove existing destination files, This is used to update a link's target or destination.
Example:
ln -sf /tmp/test /tmp/test.link; ls -go /tmp |grep test
-rw-r--r-- 1 0 Jun 8 17:19 test
lrwxrwxrwx 1 9 Jun 8 17:27 test.link -> /tmp/test
But, as you can see, it will give the absolute path if absolute paths are in ln's arguments. Giving a full path is necessary when the present working directory is different than the link's parent directory.
Relative Paths:
ln -sfr:
The -r or --relative creates symbolic links relative to the link's location.
Example:
ln -sfr /tmp/test /tmp/test.link ; ls -go /tmp| grep test
-rw-r--r-- 1 0 Jun 8 17:19 test
lrwxrwxrwx 1 4 Jun 8 17:27 test.link -> test
But, updating a link to a directory will not work if the target is a directory.
Example:
ln -sf /tmp/testdir /tmp/testdir.link ; ls -go /tmp |grep testdir
drwxr-xr-x 2 4096 Jun 8 17:48 testdir
lrwxrwxrwx 1 7 Jun 8 17:47 testdir.link -> testdir
As you can see, despite using absolute path names given in ln's argument above without the -r option, the symbolic link is still relative to the link.
Update Links to Directories:
ln -sfrn:
The -n or --no-dereference treats LINK_NAME as a normal file if it is a symbolic link to a directory.
Example:
ln -sfn /tmp/testdir /tmp/testdir.link; ls -go /tmp| grep testdir
drwxr-xr-x 2 4096 Jun 8 17:48 testdir
lrwxrwxrwx 1 12 Jun 8 17:48 testdir.link -> /tmp/testdir
As contrasted with:
ln -sfnr /tmp/testdir /tmp/testdir.link; ls -go /tmp| grep testdir
drwxr-xr-x 2 4096 Jun 8 17:48 testdir
lrwxrwxrwx 1 7 Jun 8 17:48 testdir.link -> testdir
$ touch test1 test2
$ ln -sf test2 test1
$ ls -l test[12]
lrwxrwxrwx 1 user01 user01 5 2012-05-17 14:41 test1 -> test2
-rw-r--r-- 1 user01 user01 0 2012-05-17 14:41 test2