the meaning of "~" (was: Terminal)

[Markus Schönhaber]

sg1:

> Moving from director to directory I am using cd ~/name of director the
> terminal is not recognising  the "~" for some reason.'

The "~" is recognized as expected. Your expectation is wrong.
The shell expands "~" to the path to the home directory of the effective
user.

> sg1 at sg1-desktop:~$ sudo su

Now you're not sg1 any more - you're root instead.

> root at sg1-desktop:/home/sg1# cd ~/Desktop
> bash: cd: /root/Desktop: No such file or directory

The shell expands "~" to the path of the effective user, root (remember:
you're not sg1 any more), which is /root.
What you do above is the same as doing
cd /root/Desktop
literally.

> root at sg1-desktop:/home/sg1# 
> 
> For example trying to move from sg1 to desktop and back again, no luck
> so far.

Why do you do
sudo su
in the first place? What problem are you really trying to solve?

https://help.ubuntu.com/community/RootSudo

-- 
Regards
  mks