Change permission problem

[juno2]

My RH8 suddenly have the following permission problem , the root can't modify the file.

[root@MICT root]# chmod 655 /etc/passwd
chmod: changing permissions of `/etc/passwd': Read-only file system

Can suggest what this happen ? thx

[Stuart Browne · Accepted solution]

What does:

mount

say about the / file system? Is it mounted 'ro' for some reason?

You might also what to check what the attributes of the file are (although I beleive it would say a different error if it was immutable (lsattr /etc/passwd)).

You might need to:

mount -oremount,rw -L/ /

The cause of why the root filesystem is ro is a bit of a concern.. Have you done anything funny with it in the last few days?