Getting 'You are in emergency mode. After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode' after rebooting Linux Mint 21.1 Vera

On my Linux Mint 21.1 Vera machine, rebooting the machine would show the following early in the boot process

You are in emergency mode. After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode.
Press Enter for maintenance
(or press Control-D to continue):

For my specific case this happended because I have a USB drive connected to the CPU. Removing the the USB drive and rebooting the machine allow me to continue with the boot process.

Install TightVNC server on Linux Mint 21.1 Vera

One of the options to manage VirtualBox GUI on a Linux host is via VNC server. Below is quick setup to get it up and running.

$: sudo apt install tightvncserver

It is handy to be able to maintain the same session when connecting to Linux, so let's install tmux, like so:

$: sudo apt install tmux

Once TightVNC server and tmux are installed, run the following to create a session:

$: tmux
$: tightvncserver -nolisten tcp :1 -geometry 1024x768

The above commands creates a new tmux session and runs a new VNC server with geometry of 1024x768 on port :1

In multiple cases, I have observed that the VNC session created was just a solid gray backgroun, no xterm, no nothing. As a work-around install XFCE4 like below

$: sudo apt install xfce4 xfce4-goodies

Then update ~/.vnc/xstartup like below.

#!/bin/sh

xrdb "$HOME/.Xresources"
xsetroot -solid grey
#x-terminal-emulator -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
#x-window-manager &
# Fix to make GNOME work
export XKL_XMODMAP_DISABLE=1
/etc/X11/Xsession &
startxfce4 &

Add hard drive into Linux Mint 21.1 Vera/Ubuntu/Debian

This is a condensed version on how to add hard disk into Linux Mint/Ubuntu/Debian. First check hard drives in the system, like so:

$: sudo lshw -C disk

It should show (partial data only) like this:

*-disk:1
   description: ATA Disk
   product: WDC WD3200AAKX-0
   vendor: Western Digital
   physical id: 1
   bus info: scsi@1:0.0.0
   logical name: /dev/sdb
   version: 1H15
   serial: WD-WMC2E0871450
   size: 298GiB (320GB)
   capabilities: partitioned partitioned:dos
   configuration: ansiversion=5 logicalsectorsize=512 sectorsize=512 signature=e32ff1f9

Using parted, let's now configure the harddisk/partition

$: sudo parted /dev/sdb

In parted prompt, create a new GPT partition table

(parted) mklabel gpt

Change the default unit to GB

(parted) unit GB

Create one partition occupying all the space on the drive

(parted) mkpart primary ext4 0 100%

Check to verify the layout

(parted) print

It should show something like below:

Model: ATA WDC WD3200AAKX-0 (scsi)
Disk /dev/sdb: 320GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End    Size   File system  Name     Flags
 1      0.00GB  320GB  320GB  ext4         primary

Save and quit parted

(parted) quit

Format the partition using ext4

$: sudo mkfs -t ext4 /dev/sdb1

Formatting process should show something like below:

mke2fs 1.46.5 (30-Dec-2021)
/dev/sdb1 contains a ext4 file system labelled 'VMs'
        last mounted on /mnt/b41faa95-6135-47f6-a24e-ed1909d6fc18 on Sun Dec 25 19:06:43 2022
Proceed anyway? (y,N) y
Creating filesystem with 78142464 4k blocks and 19537920 inodes
Filesystem UUID: 1b7f46da-9aa6-4c30-afec-d983f35a19d5
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872, 71663616

Allocating group tables: done
Writing inode tables: done
Creating journal (262144 blocks):
done
Writing superblocks and filesystem accounting information: done

Now let us create a mount point

$: sudo mkdir /mnt/vmdisk

Add an entry in fstab to automount the new partition

$: sudo vim /etc/fstab

Add a line entry in fstab like below

/dev/sdb1    /mnt/vmdisk   ext4    defaults     0        0

We should be able to use the partition without rebooting, so mount it manually for now.

$: sudo mount /mnt/vmdisk

Add directory to be writable by user

$: sudo mkdir /mnt/vmdisk/vms

Make the user named timus owner of the new folder

$: sudo chown -R timus:timus /mnt/vmdisk/vms

Refs:
https://help.ubuntu.com/community/InstallingANewHardDrive

Install VirtualBox 7.0.4 on Linux Mint 21.1 Vera

▣ Download VirtualBox 7.0.4 from www.virtualbox.org, select Ubuntu 22.04.

▣ Once download is complete, open a terminal and run the following:

$: cd Downloads/
$: sudo dpkg -i virtualbox-7.0_7.0.4-154605~Ubuntu~jammy_amd64.deb
$: sudo apt -f install
$: sudo usermod -a -G vboxusers timus

Replace timus with the current user

Show Debian/Ubuntu/Mint package version using apt-cache

$: apt-cache show monodevelop | grep Version

The type or namespace name `Gtk' could not be found. Are you missing an assembly reference?

After fixing items below related to MonoDevelop on Linux Mint 7.3, another error shows up:
http://8thstring.blogspot.com/2016/01/monodevelop-does-not-start-on-linux.html
http://8thstring.blogspot.com/2016/01/could-not-obtain-c-compiler-c-compiler.html

The type or namespace name `Gtk' could not be found. Are you missing an assembly reference?

To fix install gtk-sharp-2.0 libraries, like:

$: sudo apt-get install gtk-sharp2