[Xymon] Detecting read-only file system in Linux

On 11 March 2015 at 00:44, Thomas Eckert <thomas.eckert at it-eckert.de> wrote:

Just for future reference as you already found your solution:

From looking at the util-linux package I understand that _if_ the /proc-filesystem is mounted the information is used from there.

I don't think this is the case. Running "strace" on the "mount" command shows that it first looks at /etc/mtab, and if that exists, it doesn't look at /proc/mounts. Only if /etc/mtab doesn't exist, does mount look at /proc/mounts.

So in a situation where the filesystem containing /etc is having problems and goes read-only, /etc/mtab won't get updated because it's now read-only.

J