Stage $4$: Changing directories $10$ marks

cd $$ change working directory

This command has two forms. In the first, it has no parameters and changes the working

directory to the user$$s home directory. In the second, it has one parameter which is a

directory $($either in full path or relative path form$)$ and changes the working directory

to the directory provided as a parameter. If the directory provided does not exist, then

it should say that there is no such directory. In fact, you must go further and utilise the

error value of the system calls using the perror$()$ function. The shell should check

appropriate parameters are used by the user and provide informative messages if this

is not the case. Note, though, that any string could be considered a path as far as the

command is concerned.

Remember that directory changes are effected with the chdir$()$ function.

Remember that $.$ and $..$ refer to the current and the parent directory and they can be

used as part of the path.