Consider the following command line snippet:
$ cd /tmp/
$ mkdir dirA
$ mkdir dirB
$ echo "the contents of the 'original' file" > orig.file
$ ls -la orig.file
-rw-r--r-- 1 $USER $USER 36 2010-12-26 00:57 orig.file
# create symlinks in dirA and dirB that point to /tmp/orig.file:
$ ln -s $(pwd)/orig.file $(pwd)/dirA/
$ ln -s $(pwd)/orig.file $(pwd)/dirB/lorig.file
$ ls -la dirA/ dirB/
dirA/:
total 44
drwxr-xr-x 2 $USER $USER 4096 2010-12-26 00:57 .
drwxrwxrwt 20 root root 36864 2010-12-26 00:57 ..
lrwxrwxrwx 1 $USER $USER 14 2010-12-26 00:57 orig.file -> /tmp/orig.file
dirB/:
total 44
drwxr-xr-x 2 $USER $USER 4096 2010-12-26 00:58 .
drwxrwxrwt 20 root root 36864 2010-12-26 00:57 ..
lrwxrwxrwx 1 $USER $USER 14 2010-12-26 00:58 lorig.file -> /tmp/orig.file
At this point, I can use readlink to see what is the 'original' (well, I guess the usual term here is either 'target' or 'source', but those in my mind can be opposite concepts as well, so I'll just call it 'original') file of the symlinks, i.e.
$ readlink -f dirA/orig.file
/tmp/orig.file
$ readlink -f dirB/lorig.file
/tmp/orig.file
... However, what I'd like to know is - is there a command I could run on the 'original' file, and find all the symlinks that point to it? In other words, something like (pseudo):
$ getsymlinks /tmp/orig.file
/tmp/dirA/orig.file
/tmp/dirB/lorig.file
I've not seen a command for this and it's not an easy task, since the target file contains zero information on what source files point to it.
This is similar to "hard" links but at least those are always on the same file system so you can do a find -inode to list them. Soft links are more problematic since they can cross file systems.
I think what you're going to have to do is basically perform an ls -al on every file in your entire hierarchy and use grep to search for -> /path/to/target/file.
For example, here's one I ran on my system (formatted for readability - those last two lines are actually on one line in the real output):
pax$ find / -exec ls -ald {} ';' 2>/dev/null | grep '\-> /usr/share/applications'
lrwxrwxrwx 1 pax pax 23 2010-06-12 14:56 /home/pax/applications_usr_share
-> /usr/share/applications