$ touch file1
$ ls -li file1
4210927 -rw-r--r--   1 fletch  wheel  0 Dec  8 11:15 file1
$ perl -e 'link( "file1" => "file2" ) or die "$!"'
$ ls -li
total 0
4210927 -rw-r--r--   2 fletch  wheel  0 Dec  8 11:15 file1
4210927 -rw-r--r--   2 fletch  wheel  0 Dec  8 11:15 file2
$ echo "Through file2" >> file2
$ ls -li
total 16
4210927 -rw-r--r--   2 fletch  wheel  14 Dec  8 11:15 file1
4210927 -rw-r--r--   2 fletch  wheel  14 Dec  8 11:15 file2
$ cat file1
Through file2
$ rm file1
$ cat file2
Through file2
$ ls -li
total 8
4210927 -rw-r--r--   1 fletch  wheel  14 Dec  8 11:15 file2