System Administration Links – Perceptual Gestalt

chroot

An excellent guide from Bart Simons

Classics

Support and Help

Password Recovery

[CentOS] Reset Root Password (single user mode)

If you don’t remember the root password, or you just want to boot in the most minimal way, you can add init=/bin/bash to your linux line to bypass the regular init sequence and just drop to a shell. The line should look like

linux /vmlinuz-xxx root=xxx ro init=/bin/bash

Whatever is after vmlinuz and root (where the xxxs are) leave as-is. You can remove everything else on that line except for the leading word linux, vmlinuz, root and ro. Add init=/bin/bash

The system ought to boot and present a bash shell running as user root. If your system has full-disk encryption, you will need to enter the encryption password.

At this command line, run the following commands:

mount -o remount,rw /
mount /proc

Then you can view and modify the user database. The main user database file is /etc/passwd. It contains user names (for both physical users and system accounts), but passwords are in a different file /etc/shadow. If you’ve forgotten a password, you can’t recover it, all you can do is change it.

If you want to change the password for an account, run

passwd root

to change user root’s password.

If you see a token manipulation error then make sure you booted into an environment that supports read/write (use rw in linux line or remount as rw).

Once you’re finished, you can reboot.

umount /
reboot

[CentOS] Reset Root Password (live CD chroot mode)

Boot into your live environment
Make directory on which to mount your partition
```
mkdir ./mnt || /bin/true
```
Identify your disks using fdisk
```
fdisk -l
```
Look for the bootable partition of type Linux
If your partition is a standard Linux partition:
```
mount /dev/sda1 ./mnt
```

If your partition is a Linux LVM:

pvscan
vgscan
vgchange -a y
lvscan
mount /dev/sda1 ./mnt
mount --bind /dev ./mnt/dev<
mount --bind /proc ./mnt/proc
mount --bind /sys ./mnt/sys

Change root into your mounted directory
```
chroot ./mnt /bin/bash
```
Type passwd and enter a new password
Type reboot to reboot your system

Provisioning

Foreman – PXEless Bare Metal & Virtual Machine Provisioning

Volume Management

[LVM] Working With LVM Volumes