I had an accident with /etc/passwd - using putpwent(), I replaced the first line of /etc/passwd with mine.
Unfortunately this line used to belong to root.
Now I don't have root permission, and I can't change it back.
The file belongs to user 0 group root:
-rw-r--r-- 1 0 root 1.8K Jan 9 11:33 passwd
Any idea how to recover?