システムには完全修飾ドメイン名（fqdn）が必要です。

次のようないくつかのQtライブラリをインストールしようとしています。

sudo apt-get install libqt5webengine5  libqt5webenginewidgets5

ところで、次のようなエラーが発生します。

The hostname -f command returned: $1

Your system needs to have a fully qualified domain name (fqdn) in
order to install the var-qmail packages.

Installation aborted.

dpkg: error processing package qmail (--configure):
 installed qmail package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of qmail-run:
 qmail-run depends on qmail (>= 1.06-2.1); however:
  Package qmail is not configured yet.

No apport report written because the error message indicates its a followup error from a previous failure.
                          dpkg: error processing package qmail-run (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 qmail
 qmail-run
E: Sub-process /usr/bin/dpkg returned an error code (1)

このライブラリをどのようにインストールしますか？

編集する：

ls: cannot access '–l': No such file or directory
qmail.list
qmail.md5sums
qmail.postinst
qmail.postrm
qmail.preinst
qmail-run.conffiles
qmail-run.list
qmail-run.md5sums
qmail-run.postinst
qmail-run.postrm
qmail-run.preinst
qmail-uids-gids.list
qmail-uids-gids.md5sums
qmail-uids-gids.postinst
qmail-uids-gids.postrm
qmail-uids-gids.preinst

The hostname -f command returned: Lenovo-V330-15IKB

You must have a fully qualified domain name (fqdn) for your system
to install the qmail and qmail-run packages.

Installation aborted.

dpkg: error processing package qmail-run (--configure):
 installed qmail-run package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 qmail-run
E: Sub-process /usr/bin/dpkg returned an error code (1)

エラーがアクティブです。sudo dpkg --configure -a

Setting up qmail-run (2.0.2+nmu1) ...

The hostname -f command returned: hammad-Lenovo-V330-15IKB

You must have a fully qualified domain name (fqdn) for your system
to install the qmail and qmail-run packages.

Installation aborted.

dpkg: error processing package qmail-run (--configure):
 installed qmail-run package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 qmail-run