I have a PC with Ubuntu 16.04 installed. Recently I want to install some packages but have trouble installing them. After some digging, I found that the failure seems to be related to the linux user account system. The problem is that any file with a name prefixed by passwd. cannot be created in /etc path.
# ls /etc/passwd.*
ls: cannot access '/etc/passwd.*': No such file or directory
# touch /etc/passwd.test-test-test
touch: cannot touch '/etc/passwd.test-test-test': Permission denied
# ls /etc/passwe.* …