Significance of forward slash(/) while specifying a directory

Shell Programming and Scripting
1

What is the significance of the forward slash(/) while specifying a directory?

cp -av /dir/ /opt/
and
cp -av /dir /opt

Does effectively the same job it seems?

2

directories are also treated as files in unix.
filenames are unique whether its a file or dir.
i dont think you need to provide "/" at all.

3

A forward slash seems to just be a default delimiter when it comes to the shell interpreting paths, something to be aware of when inserting variables into paths. For example: -

poweredge:/home/brad>cd /home//brad/bin
poweredge:/home/brad/bin>

So be mindful that if the variable is a null string the path will not cause an error if it still evaluates to a valid path.

poweredge:/home/brad>DIR=""
poweredge:/home/brad>cd /home/$DIR/brad/bin
poweredge:/home/brad/bin>