The directory stack is a list of recently-visited directories. The
pushd builtin adds directories to the stack as it changes
the current directory, and the
popd builtin removes specified
directories from the stack and changes the current directory to
the directory removed. The
dirs builtin displays the contents
of the directory stack. The current directory is always the "top"
of the directory stack.
The contents of the directory stack are also visible
as the value of the
DIRSTACK shell variable.