You need to mount the disks or partitions that you want to use to a folder or mount point before the data within it is accessible. From there, you'll be able to navigate the filesystem and perform read or write operations.

You can manually mount disks and partitions each time you need to use them, or you can add an entry in /etc/fstab, so it automatically mounts every time your system boots. You can mount these drives via the device name, label, or UUID.

Related: How to mount disk partition using UUID in Linux

Steps to mount disk or partition in Linux:

  1. Launch terminal.
  2. Get disk or partition name that you want to mount. 

    $ lsblk NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT loop0    7:0    0  55.4M  1 loop /snap/core18/1944 loop1    7:1    0  55.4M  1 loop /snap/core18/1932 loop2    7:2    0 217.9M  1 loop /snap/gnome-3-34-1804/60 loop3    7:3    0   219M  1 loop /snap/gnome-3-34-1804/66 loop4    7:4    0  64.8M  1 loop /snap/gtk-common-themes/1514 loop5    7:5    0    51M  1 loop /snap/snap-store/518 loop6    7:6    0  62.1M  1 loop /snap/gtk-common-themes/1506 loop7    7:7    0    51M  1 loop /snap/snap-store/498 loop8    7:8    0  31.1M  1 loop /snap/snapd/10707 loop9    7:9    0  31.1M  1 loop /snap/snapd/10492 sda      8:0    0    20G  0 disk  ├─sda1   8:1    0     1M  0 part  ├─sda2   8:2    0   513M  0 part /boot/efi └─sda3   8:3    0  19.5G  0 part / sdb      8:16   0    20G  0 disk  └─sdb1   8:17   0    20G  0 part  sr0     11:0    1  1024M  0 rom

  3. Check filesystem type of the disk or partition. 

    $ blkid /dev/sdb1 /dev/sdb1: UUID="ccab0f8d-3b5b-4189-9da3-23c49159c318" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="c088a647-01"

  4. Create a directory for mount point if it doesn't already exist. 

    $ mkdir disk

  5. Manually mount partition using mount. 

    $ sudo mount -t ext4 /dev/sdb1 disk [sudo] password for user:

  6. Check if drive was successfully mounted. 

    $ df -h Filesystem      Size  Used Avail Use% Mounted on tmpfs           391M  1.8M  389M   1% /run /dev/sda3        20G  7.1G   12G  39% / tmpfs           2.0G     0  2.0G   0% /dev/shm tmpfs           5.0M     0  5.0M   0% /run/lock tmpfs           4.0M     0  4.0M   0% /sys/fs/cgroup /dev/sda2       512M  7.8M  505M   2% /boot/efi tmpfs           391M  112K  391M   1% /run/user/1000 /dev/sdb1        20G   45M   19G   1% /home/user/disk

  7. Unmount previously mounted drive. 

    $ sudo umount /dev/sdb1

  8. Open /etc/fstab using your preferred text editor. 

    $ sudo vi /etc/fstab

  9. Add an entry for a new mount point. 

    /dev/sdb1       /home/user/disk ext4    defaults        0       0

  10. Mount all filesystems in /etc/fstab. 

    $ sudo mount -a

  11. Check if drive or filesystem is mounted successfully. 

    $ df -h Filesystem      Size  Used Avail Use% Mounted on tmpfs           391M  1.8M  389M   1% /run /dev/sda3        20G  7.1G   12G  39% / tmpfs           2.0G     0  2.0G   0% /dev/shm tmpfs           5.0M     0  5.0M   0% /run/lock tmpfs           4.0M     0  4.0M   0% /sys/fs/cgroup /dev/sda2       512M  7.8M  505M   2% /boot/efi tmpfs           391M  112K  391M   1% /run/user/1000 /dev/sdb1        20G   45M   19G   1% /home/user/disk