Because the sym-links must be either:
$HOME, or by the shell shortcut
~/, or by the absolute path
/home/yourusername/, or by the relative path
./(because it’s the directory we’re currently in.
ln -s fun fun.sym
ln -s ../fun dir1/fun-sym
fun-symto be put into a sub-directory called
dir1/(which is the same as the relative path
./dir1, or the absolute paths
dir1, then as a relative path, it’s target will be up one directory. So if you are going to use a relative path to the target, the path must be in relation to where the sym-link WILL be. NOT in relation to where we currently are. Therefore, you must use the relative path
../funfor the sym-links target.
ln -s $HOME/fun dir1/fun-sym
ln -s ~/fun ./dir1/fun-sym
ln -s /home/yourusername/fun ./dir1/fun-sym
./dir1are both exactly the same thing.