Robert P. J. Day wrote:
something i brought up a while back but, in order to prevent myself
doing something incredibly dumb and wiping out anything under /usr by
accident, i like to mount the /usr filesystem as read-only.
occasionally, when i've tried to do that manually, i've been
disallowed with the error that that filesystem is currently busy, and
one of the possible reasons is that prelink was running.
more generally, i'm assuming that (re)mounting /usr readonly will
always be disallowed if anything is currently open for write, and the
simplest way to check for that that i use is:
$ fuser -muv /usr
USER PID ACCESS COMMAND
/usr: rpjday 3142 ...e. (rpjday)gnome-keyring-d
rpjday 3143 ...e. (rpjday)gnome-session
rpjday 3208 ...e. (rpjday)dbus-launch
rpjday 3216 ...e. (rpjday)gconfd-2
rpjday 3220 ...e. (rpjday)gnome-settings-
rpjday 3228 ...e. (rpjday)gconf-helper
rpjday 3229 ...e. (rpjday)metacity
rpjday 3230 ...e. (rpjday)gnome-panel
rpjday 3232 ...e. (rpjday)nautilus
rpjday 3236 ...e. (rpjday)gnome-volume-ma
rpjday 3238 ...e. (rpjday)bonobo-activati
rpjday 3245 ...e. (rpjday)gnome-vfs-daemo
rpjday 3247 ...e. (rpjday)bluetooth-apple
rpjday 3253 ...e. (rpjday)nm-applet
rpjday 3254 ...e. (rpjday)puplet
rpjday 3255 ...e. (rpjday)python
rpjday 3261 ...e. (rpjday)pam-panel-icon
rpjday 3262 ...e. (rpjday)gnome-power-man
rpjday 3267 ...e. (rpjday)/usr/bin/sealer
rpjday 3294 ...e. (rpjday)gnome-screensav
rpjday 3306 ...e. (rpjday)mapping-daemon
rpjday 3327 ...e. (rpjday)wnck-applet
rpjday 3329 ...e. (rpjday)trashapplet
rpjday 3347 ...e. (rpjday)gam_server
rpjday 3361 ...e. (rpjday)notification-ar
rpjday 3363 ...e. (rpjday)fast-user-switc
rpjday 3365 ...e. (rpjday)clock-applet
rpjday 3367 ...e. (rpjday)mixer_applet2
rpjday 3371 ...e. (rpjday)gnome-terminal
rpjday 3381 ....m (rpjday)bash
rpjday 3462 f...m (rpjday)firefox
rpjday 3482 f...m (rpjday)run-mozilla.sh
rpjday 3487 f..e. (rpjday)firefox-bin
rpjday 3524 ....m (rpjday)bash
rpjday 3905 f..e. (rpjday)npviewer.bin
rpjday 4062 ....m (rpjday)bash
now, according to the man page for fuser, anything open for write
will be identified with an "F", so the above should be good and, in
fact, the remount worked.
can i assume that, as long as nothing is open for write, the
read-only remount should work? is there any other reason that i would
be told that the device is busy. put another way, if i run the above
command and don't see an "F", should the remount always work?
rday
Add ro to the mount options in /etc/fstab and see what complains.
This is supposed to work, and if you're running 100 or more Linux guests
on a Zed box (folk run a lot more than this) it's highly likely you want
to do this.
--
Cheers
John
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