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Re: how to change root passwd (if forgotten)

On Wed, Aug 10, 2011 at 11:25 AM, abdelkader belahcene
<abelahcene@gmail.com> wrote:
> Hi,
> I ve forgotten my root passwd on centos 6 (red hat based),
> I tried to change it as I used in debian (in debian it works perfectly) ,
> that is:
> use a cd live (or installation cd1), to access the hd,
> I mount  my root partition and mount proc and devices

Definitely the wrong newsgroup, but:

        * boot with CentOS, RHEL, or Scientific Linux rescue CD
        * Select "linux rescue" or rescue mode from the CD boot process.
        * Allow it to mount your old system at /mnt/sysimage with all
the relevant /dev and /dev/sys utilities under it.
        * Do "chroot /mnt/sysimage" to enter the environment of the
mounted directories, in a chroot cage.
        * THEN do "passwd root"
        * Exit the chroot. (Just type "exit").
        * Sync the disk changes, just as a precaution. (Just type "sync")
        * Reboot and eject CD.

I generally setup PXE to make these tools available without a CD in
large environments,. The "chroot" business is core to updating messed
up grub configurations, password files, kernels, fstab, or core system

> I tried  the command passwd, no error reprorted, but after reboot the passwd
> had´t changed.
> then I decided to remove passwd from /etc/shadow (delete the
> second field).

> OK,  now I can access my machine  without passwd,  BUT I CAN´T GIVE ANY
> # passwd
> Changing password for user root.
> New password:
> Retype new password:
> passwd: Authentication token manipulation error
> any idea to fix the problem.
> thanks a lot

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