A few days ago I found the following command:

```
for i in 0 1 2 3 4 5 6 S ; do ln -s /etc/rc$i.d /etc/rc.d/rc$i.d ; done

```

As far as understand this command is going to create a symbolic link between each file using the for cycle, but **what I can't really understand is the S in that numeration, what is it supposed to do?**