Having /var/run separately mounted?

[Aaron LI]

On April 28, 2020 6:31:32 PM GMT+08:00, Michael Neumann <mneumann at ntecs.de> wrote:
>On Tue, Apr 28, 2020 at 07:14:43AM +0000, Dr. Martin Ivanov wrote:
>> <div>I would like to have /var/run mounted separately as it is not a
>directory to be backed up.</div>
>> <div><br>
>> </div>
>> <div>I tried mounting it as a tmpfs or as a null mount under /build.
>In both cases it did not work, because some processes write to /var/run
>before it is mounted and some after that. In particular, problems arise
>due to the shared memory, which has to be mounted
>
>Have you tried adding an entry to fstab like this:
>
>/build/var.run	/var/run	null	rw	0	0
>
>This should then be mounted automatically by /etc/rc.d/mountcritlocal.
>Once mountcritlocal has mounted the local file systems it will create a
>/var/run/shm entry. So your /build/var.run should have a `shm`
>subdirectory.
>
>If you want to mount /var/run as tmpfs then you have to edit
>/etc/rc.d/mountcritlocal slightly. Right at the end you will find:
>
>	mount_tmpfs -m 01777 dummy /var/run/shm
>	mkdir -p -m 01777 /var/run/shm/tmp
>
>If /var/run should be a tmpfs, the `shm` directory and other
>directories
>will not exist and you have to create them. Take a look at
>/etc/mtree/BSD.var.dist and search for `var`. You will find the
>subdirectories and their modes that you have to create. Create those
>directories right before the `mount_tmpfs` call above.
>
>Haven't tried that myself, but I think that should work.
>
>Regards,
>
>  Michael

I'd like we improve the RC script and provide a configuration like 'tmpfs_var_run=YES' to mount a tmpfs at /var/run.  And in such a case, we can just create /var/run/shm with mode 01777 and without mounting another tmpfs.

In addition, we can do the same for /tmp.

Cheers,
-- 
Aaron