problem related to read only file system in single user root login

[Matthew Seaman]

On 05/01/2014 09:06, Aravind Gopal wrote:
> Sir,
> Sorry to bother you, I have a severe problem and I failed to solve it
> myself.
> I am new to freebsd and I have average knowledge about Linux.
> What I have done is
> 1) Installed FreeBSD 9.2 amd64(to a system with AMD phenom X4 840)
> 2) Added a normal user(As I don't know about 'wheel' group, 'wheel' group
> was not added).
> 3) Installed xorg and kde, as described in the handbook.
> 4) restarted and entered in to the normal user(KDE).
> 5) but could not upgrade/update/install new program/mount filesystem from
> the normal user with kde.
> 6) As From kde loging screen, root login is not allowed.
> 7) restarted and selected the 'single user mode' and logged in to 'root'
> 8) as per the documentation I tried to add user to the 'wheel' group using
> 'pw groupmod'. But failed and the system message was 'read only file
> system'.
> 
> 
> As my cpu is amd and the annoying bug in the kernel is fixed in freeBSD 10,
> I need to upgrade. also i want to mount other partitions.
> 
> Frankly speaking I abandoned the pc After the failure of my trouble
> shooting.
> 
> Do I need to install freeBSD again?
> 
> please help....
> 

In order to fix this, you need a root shell.  As you've discovered, on
*BSD your userid needs to be a member of the wheel group in order to use
su(1).  I assume you don't have sudo(8) installed?  Worth checking, but
I doubt you'll get any joy from it, as it needs the sudoers file to be
configured, and I'm sure you'ld remember doing something like that.

So, you need to get a root login.  As you say, KDE doesn't let you login
directly as root.

You may be able to login via the text console.  It depends if your
graphics hardware supports switching back and forth (cards like Nvidia
and Radeon generally do: kernel mode graphics like Intel may not), and
if the command is enabled in your X configuration (it should be, by
default).  Try pressing these three keys all together:

    Ctrl - Alt - F1

If that results in a black screen with some white text, then you're in
luck.  There should be a 'login:' prompt at the bottom of the screen.
If not press return until it appears.  Then login as root, giving the
root password you will have set during the installation process.

You'll get to a root shell running tcsh -- from here you an issue your
pw(8) command to add your userid to the wheel group:

    # pw user mod -n userid -G wheel

You probably also want to run:

    # sysctl vfs.usermount=1

and edit /etc/sysctl.conf to add

   vfs.usermount=1

so that setting is recreated on reboot.

Now type 'logout' and then Ctrl-Alt-F9 which should get you back to your
KDE session.

If Ctrl-Alt-F1 doesn't get you to a usable console, then booting into
single user as you did previously is the way to go.  Once you get to the
single user shell prompt, type this:

   # mount -u -o rw /

which will remount the root partition read-write.  You can then run
the pw(8) and sysctl(8) commands as shown.  Then type Ctrl-D and the
system will carry on booting up to multi-user.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.
PGP: http://www.infracaninophile.co.uk/pgpkey


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