You don’t need to install
man pages manually, they are installed together with the command they describe. In the case of
ls the program as well as the
man page are part of the
coreutils package, see the package’s file list or the output of
dpkg -L coreutils:
$ dpkg -L coreutils | grep [^a-z]ls
man page wasn’t installed properly for any reason, just reinstall the package:
sudo apt install --reinstall PACKAGE
Though that is done automatically anytime a
man page is added in the installation of a package, you can also update the database of
If a command you seek help for is installed but has no
man page, its help may be available elsewhere, see How can I get help on terminal commands? for alternatives.
If you want to install a
man page without the corresponding package I recommend using
dman as explaned in this answer.