Physical control = Hold F8 while booting and "single user mode" can drop into a root console shell
OR: systemrescuecd or livecd, (assuming the shell executable on your hard drive works!)
echo $SHELL (ensure it's /bin/bash, if not then type: SHELL=/bin/bash) fdisk -l chroot /dev/sda1 /mnt/backup cat /etc/passwd passwd USERNAME
Once you create your "guest" user, SU to root and open /etc/passwd in a text editor. Find the line that contains the password for that user, and delete everything between the two colons.
Save then exit. Try to login as that user and you should be able to go right in without a problem.
With shadow passwords, the ``/etc/passwd'' file contains account information, and looks like this:smithj:x:561:561:Joe Smith:/home/smithj:/bin/bash
Username, up to 8 characters. Case-sensitive, usually all lowercase An "x" in the password field. Passwords are stored in the ``/etc/shadow'' file.
Numeric user id. This is assigned by the ``adduser'' script. Unix uses this field, plus the following group field, to identify which files belong to the user.
Numeric group id. Red Hat uses group id's in a fairly unique manner for enhanced file security. Usually the group id will match the user id.
Full name of user. I'm not sure what the maximum length for this field is, but try to keep it reasonable (under 30 characters).
User's home directory. Usually /home/username (eg. /home/smithj). All user's personal files, web pages, mail forwarding, etc. will be stored here.
User's "shell account". Often set to ``/bin/bash'' to provide access to the bash shell (my personal favorite shell).
Note: Note: If the account needs to provide "FTP" transfers to update web pages, then the shell account will need to be set to ``/bin/bash'' -- and then special permissions will need to be set up in the user's home directory to prevent shell logins.
The ``/etc/shadow'' file contains password and account expiration information for users, and looks like this:
Password, 13 character encrypted. A blank entry (eg. ::) indicates a password is not required to log in (usually a bad idea), and a ``'' entry (eg. ::) indicates the account has been disabled.
The number of days (since January 1, 1970) since the password was last changed.
The number of days before password may be changed (0 indicates it may be changed at any time)
The number of days after which password must be changed (99999 indicates user can keep his or her password unchanged for many, many years)
The number of days to warn user of an expiring password (7 for a full week)
The number of days after password expires that account is disabled
The number of days since January 1, 1970 that an account has been disabled
A reserved field for possible future use