Let's Visit Linux Mount and Unmount Again

Posted on Friday December 21

mount - mount a filesystem

By default, the mount command displays a list of media devices currently mounted on the system:

$ sudo mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,relatime,size=2002872k,nr_inodes=500718,mode=755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
/dev/vda1 on /boot type ext2 (rw,relatime,block_validity,barrier,user_xattr,acl)
/dev/mapper/ubuntu--vg-root on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
.....
.....

The mount command provides four information:

The device filename of the media
The mount point in the virtual directory where the media is mounted
The filesystem type
The access status of the mounted media

The basic mount option

mount -t type device directory

Windows Device type

OS	File Systems
Windows	vfat,ntfs,iso9660

Linux Device type

lsblk displays block devices

$ lsblk -f
NAME  FSTYPE  LABEL UUID MOUNTPOINT
vda
 vda1  ext2  eb311fb6-841d-4220-9994-046ff3b46721 /boot
 vda2
 vda5  LVM2_member Gx5XbE-coCx-2c9e-XuP3-qD7T-R8GR-0k0nwV
 ubuntu--vg-root ext4  e2a78946-d108-438c-ac8c-4b003f74ae64 /
 ubuntu--vg-swap_1 swap  710191d7-7abd-4fb7-b4d9-eae243cd6077 [SWAP]

To mount the USB memory stick at device /dev/sdb1 at location /media/disk, you use the following command:

mount -t vfat /dev/sdb1 /media/disk

To mount the CDROM at device /dev/cdrom at location /mnt/disk, you use the following command:

mount /dev/cdrom /mnt/cdrom

mount Command options

Parameter	Description
-a	All the filesystems listed via getfsent(3) are mounted
-d	Causes everything to be done except for the actual system call
-f	Causes the mount command to simulate mounting a device, but not actually mount it
-s	Ignores mount options not supported by the filesystem
-o	async,force,noasync,noauto,nodev,noexec,noowners,nosuid,rdonly,sync,update,union,noatime,nobrowse `mount -t hfs -o nosuid,-w,-m=755 /dev/disk2s9 /tmp`
-r	Mount the file system read-only

mounts all filesystems except those of type NFS and HFS.

mount -a -t nonfs,hfs

mounts NFS share

mount -t nfs ip_address:/dirname /mnt/localdiskname

The unmount command

To remove a removable media device, you should never just remove it from the system. Instead, you should always unmount it first

umount [directory | device ]

To unmount the data directory

sudo umount /data

If any program has a fi le open on a device, the system won't let you unmount it.

$  umount /data
umount: /data: device is busy 
umount: /data: device is busy

Mounting the Remote File System

SSHFS is Linux based software that needs to be installed on your local computer

sudo mkdir /data
sudo chown user:group /data
sudo sshfs -o allow_other,defer_permissions root@:/ /mnt/data
or for Key Based
sudo sshfs -o allow_other,defer_permissions,IdentityFile=~/.ssh/id_rsa root@:/ /mnt/data

How to Make a Mount Point

A mount point is "just" a directory. So all you need to do is to create a directory, then mount it, the only tricky part is the device name which you are mounting

mkdir /data
chown user:group /data
mount /dev/sdb1 /data

/dev/sda - raw device
/dev/sda1 - virtual device, like a partition

Device Names

IDE controller naming convention

drive name	drive controller	drive number
/dev/hda	1	1
/dev/hdb	1	2
/dev/hdc	2	1
/dev/hdd	2	2

partition names

drive name	drive controller	drive number	partition type	partition number
/dev/hda1	1	1	primary	1
/dev/hda2	1	1	primary	2
/dev/hda3	1	1	primary	3
/dev/hda4	1	1	swap	NA
/dev/hdb1	1	2	primary	1
/dev/hdb2	1	2	primary	2
/dev/hdb3	1	2	primary	3
/dev/hdb4	1	2	primary	4