sudo apt-get install -fを実行してみたところ、次のメッセージが表示されました。
setting up chkrootkit (0.53-1) ...
debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable
dpkg: error processing package chkrootkit (--configure):
installed chkrootkit package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of bsd-mailx:
bsd-mailx depends on default-mta | mail-transport-agent; however:
Package default-mta is not installed.
Package mail-transport-agent is not installed.
dpkg: error processing package bsd-mailx (--configure):
dependency problems - leaving unconfigured
Setting up rkhunter (1.4.6-8) ...
debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable
dpkg: error processing package rkhunter (--configure):
installed rkhunter package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
chkrootkit
bsd-mailx
rkhunter