How do you mount a directory from another partition?

First, mount the external drive to a specific location (in this case, /mnt/tmp). Note: If you don’t have a /tmp directory, create it.

    UUID=2d571cd6-510c-4f4f-8de7-f4b198747cf2	/mnt/tmp	ext4	defaults0	0

Next, mount the desired directory.

    /mnt/tmp/biswajit/Videos/	/srv/jellyfin	none	bind	0	0

Is mounting using the mount command permanent?

No, mounting using the mount command results in only a temporary change. We can mount any drive to any folder we desire i.e we can mount an external drive to /mnt/tmp (though it is a standard practice we can use folders like this /home/bb/Downloads also). Example:

    sudo mount /dev/sdb3 /home/bb/Downloads

What is the permanent solution?

The permanent solution involves modifying the /etc/fstab file. Here is an example:

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a device; this may
# be used with UUID= as a more robust way to name devices that works even if
# disks are added and removed. See fstab(5).
#
# <file system>             <mount point>  <type>  <options>  <dump>  <pass>
UUID=731C-5C80                            /boot/efi      vfat    umask=0077 0 2
UUID=30c9dc23-fc45-450c-9e65-7d95502e22d4 swap           swap    defaults,noatime 0 0
UUID=e91a3d2f-a2e7-4c21-9186-de10b5193ff4 /              ext4    defaults,noatime 0 1
tmpfs                                     /tmp           tmpfs   defaults,noatime,mode=1777 0 0
UUID=869f474f-bad6-4793-b8eb-3646dc058036	/home/bb/Downloads	ext4	defaults	0	2
UUID=2d571cd6-510c-4f4f-8de7-f4b198747cf2	/mnt/tmp	ext4	defaults0	0
/mnt/tmp/biswajit/Videos/	/srv/jellyfin	none	bind	0	0

Unmount Example

sudo umount /tmp

TIPS

Avoid using commands like this for directory mounting from a different drive:

sudo mount -o bind /run/media/bb/2d571cd6-510c-4f4f-8de7-f4b198747cf21/biswajit/Videos/ /srv/jellyfin

It never works :(