root@seymour:~# mount   -o  rw,remount  /

NOTE

You now have    complete    root    access  and read/write  privileges  on  the

machine.    This    is  an  example of  why security    of  a   physical    machine is

important.  If  someone has physical    access  to  your    computer    and knows

what    he  or  she is  doing,  that    person  can easily  and quickly gain    full    control

over    the machine and all it  contains.

If the problem exists because the user account was removed from the admin
group, enter the following:

Click here to view code image
root@seymour:~# adduser username admin

If the problem exists because the permissions for /etc/sudoers are
wrong, enter this:

Click here to view code image
root@seymour:~# chmod 440 /etc/sudoers

If the problem exists because of an internal problem in /etc/sudoers,
make a backup of the existing file and use visudo to edit it. (This is a
special use of the vi editor, covered in Chapter 12, “Command-Line Master
Class, Part 2,” that runs a check on the file after editing to be certain it is
correct; this particular problem usually occurs when someone edits the file
using another editor that does not make this check.) The contents of the file
should be as follows:

Click here to view code image

This file MUST be edited with the 'visudo' command as root.

Please consider adding local content in /etc/sudoers.d/ instead of

directly modifying this file.

See the man page for details on how to write a sudoers file.

Defaults env_reset
Defaults
secure_path="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

#   Host    alias   specification

#   User    alias   specification

#   Cmnd    alias   specification