root@v1:~#
root@v1:~# touch /etc/subuid.lock
root@v1:~# useradd -m user
useradd: existing lock file /etc/subuid.lock without a PID
useradd: cannot lock /etc/subuid; try again later.
root@v1:~#
root@v1:~# rm /etc/subuid.lock
root@v1:~#
root@v1:~# useradd -m user
root@v1:~#
root@v1:~# userdel -r user
userdel: user mail spool (/var/mail/user) not found
root@v1:~#