ps -uax |grep -i dpkg
root      4167  0.0  0.0  17564   984 pts/8    S+   20:01   0:00 grep --color=auto -i dpkg
root     22248  0.0  0.0  25880  7008 pts/2    Ss+  19:07   0:00 /usr/bin/dpkg --status-fd 61 --configure --pending
root     22269  0.0  0.1  69584 20484 pts/2    S+   19:07   0:00 /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/docker.io.postinst configure 18.06.1-0ubuntu1.2~18.04.1
root     22278  0.0  0.0  16020  3468 pts/2    S+   19:07   0:00 /bin/sh /var/lib/dpkg/info/docker.io.postinst configure 18.06.1-0ubuntu1.2~18.04.1

root@we:~# sudo apt-get -f install
E: Could not get lock /var/lib/dpkg/lock-frontend - open (11: Resource temporarily unavailable)
E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), is another process using it?
root@we:~# sudo dpkg --configure -a
dpkg: error: dpkg frontend is locked by another process