Difference between passwd and passwd- file [duplicate]

Question

Possible Duplicate:
Who creates /etc/{group,gshadow,passwd,shadow}-?

I have a strange passwd- file in /etc, notice the trailing dash:

root@ubuntu:~# ls /etc/passw*
/etc/passwd  /etc/passwd-

Notice the different permissions:

root@ubuntu:~# ls -hl /etc/passw*
-rw-r--r-- 1 root root 2.0K Oct 26 13:38 /etc/passwd
-rw------- 1 root root 1.9K Oct 26 13:38 /etc/passwd-

and the difference in content:

root@ubuntu:~# diff /etc/passwd{,-}
39c39
< mysql:x:119:129:MySQL Server,,,:/nonexistent:/bin/false
---
> mysql:x:119:129::/nonexistent:/bin/false

What's happening here?

root@ubuntu:~# uname -a
Linux ubuntu 3.2.0-29-generic-pae #46-Ubuntu SMP Fri Jul 27 17:25:43 UTC 2012 i686 i686 i386 GNU/Linux
root@ubuntu:~# cat /etc/issue
Ubuntu 12.04.1 LTS \n \l

Answer 1

/etc/passwd- is a backup of /etc/passwd maintained by some tools, see the man page. There's also a /etc/shadow- usually, for the same purpose.

So, by observing the output of the command diff /etc/passwd{,-} in your question, nothing seems fishy. Someone (or something) changed the name of your mysql user.