I did a cross install of Jessie from Wheezy. When the system is booted,
there is a symlink from /etc/mtab to /proc/mounts, but /proc is empty or
not mounted. This has some consequences.
I mount proc:
# mount /proc
Now mount displays what is mounted, and proc is mounted.
mount: /proc: mount failed: Unknown error -1
In my host Wheezy system, # mount shows proc as mounted, although there
is no line to do it in fstab. But in the target Jessie disk, /proc is
empty and not mounted unless this line is present in its fstab:
none /proc proc defaults 0 0
My question is: a) how can my Wheezy system mount proc when there is no
command fstab to do it? b) why does my Jessie system not mount proc and
thus populate /proc unless the line is present?