soft links
A soft link is a file which says how to go to another file. When a program encounters a soft link, it will make a guess at whether it should ignore it, or try to get to that file.
To make a soft link to a file in the current directory, linking is easy:
fortune > $file_1
ln -s $file_1 $link_1
Now imagine your directory looks like this:
dir_0/
├── dir_1
│ └── file_1
├── dir_2
│ └── file_1
├── file_1
└── link_1
Inside dir_1
, making a soft link to dir_0/file_1
would mean putting the directions to that file:
cd dir_1
ln -s ../file_1 link_1
The real content of the file is just ‘../file_1
, so making it from another directory would mean writing exactly the same address to that file:
ln -s ../file_1 dir_2/link_2
Both symlinks are identical, except for the name.
dir_0/
├── dir_1
│ ├── file_1
│ └── link_1 <-- This one points to ../file_1
├── dir_2
│ ├── file_1
│ └── link_2 <-- This one points to ../file_1 as well.
└── file_2
Since it’s just an address, you can delete the original file, then make another.
rm file_1
ls -l dir_1/
fortune > file_1
cat dir_2/link_2
fortune | tee -a file_1
cat dir_1/link_1
Last, let’s make a link from dir_2/link_2
to dir_1/file_1
(this will delete the old link):
ln -s -f ../dir_1/file_1 dir_2/link_2
cat dir_2/link_2