How to determine your Linux system’s filesystem types

Linux systems use a number of file system types – such as Ext, Ext2, Ext3, Ext4, JFS, XFS, ZFS, XFS, ReiserFS and btrfs. Fortunately, there are a number of commands that can look at your file systems and report on the type of each of them. This post covers seven ways to display this information.

To begin, the file system types that are used on Linux systems are described below.

File system types

Ext4 is the fourth generation of the ext file system, released in 2008 and pretty much the default since 2010. It supports file systems as big as 16 terabytes. It also supports unlimited subdirectories where ext3 only supports 32,000. Yet it’s backward compatible with both ext3 and ext2, thus allowing them to be mounted with the same driver. Ext4 is also very stable, widely supported and compatible with solid state drives.

JFS is a journaling file system (thus the name) developed by IBM for AIX Unix. It allows for quick file system recovery after a crash by logging file metadata.

XFS is currently the default file system in Red Hat Enterprise Linux. Due to the way it lays out files as extents, it is less vulnerable to fragmentation than ext4.

ZFS is a file system that began life as part of Sun Microsystems’ Solaris OS. It provides robust data repair features and high storage capacity and is good for large-scale data storage.

ReiserFS is an alternative to the ext3 file system, but with better performance and some advanced features.

Btrfs (which stands for “B-tree file system”) is a file system that prioritizes data integrity, fault tolerance and easy administration. It supports advanced features like snapshots, built-in RAID, and copy-on-write.

Vfat is a file system type that contains the bootloader. It’s commonly referred to as the “boot partition”.

Tmpfs is a file system type which keeps all of its files in virtual memory.

You are unlikely to see more than a handful of these on most Linux systems.

Commands that display file system types

There are many ways to determine file system types on Linux. This section covers six different commands and one system file. The details provided by the commands often depend on options used and some require sudo privileges.

Using the lsblk command

The lsblk command provides details on specified block devices. With no options, you will see something like this:

$ lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda      8:0    0 14.9G  0 disk
├─sda1   8:1    0  600M  0 part /boot/efi
├─sda2   8:2    0    1G  0 part /boot
└─sda3   8:3    0 13.3G  0 part /home
                                /
zram0  252:0    0  3.7G  0 disk [SWAP]

As you can see, it provides partition names (e.g., sda1), major and minor device numbers (the major number is the larger, more generic category), RM (removable or not), the size, type (disk or partition) and the mount point. An RM of 0 indicates the disk or partition is not removable.

In the command below, the options used specifically request that the file system type (FSTYPE) be included.

$ lsblk -o PATH,FSTYPE,MOUNTPOINT /dev/sda
PATH      FSTYPE MOUNTPOINT
/dev/sda
/dev/sda1 vfat   /boot/efi
/dev/sda2 ext4   /boot
/dev/sda3 btrfs  /home

The lsblk command with the -f option includes file system version information, the UUIDs and both available and used space.

$ lsblk -f
NAME   FSTYPE FSVER LABEL                 UUID                                 FSAVAIL FSUSE% MOUNTPOINTS
sda
├─sda1 vfat   FAT32                       6E4A-5BD5                             581.4M     3% /boot/efi
├─sda2 ext4   1.0                         444b22ab-9206-4f97-b1c3-b8832d294401  609.4M    30% /boot
└─sda3 btrfs        fedora_localhost-live d961ea75-eaa0-425a-b378-fe2bc7e3a9ce    8.5G    32% /home
                                                                                              /
zram0                                                                                         [SWAP]

Using the blkid command

The blkid command requires the use of sudo privilege and supplies information like that shown below including the partition names, UUIDs, block size, file system type and PARTUUID (raw physical storage partition UUID).

$ sudo blkid
[sudo] password for fedora:
/dev/sda2: UUID="444b22ab-9206-4f97-b1c3-b8832d294401" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="344a7c0d-2aa0-44c1-8d49-2ea763659119"
/dev/sda3: LABEL="fedora_localhost-live" UUID="d961ea75-eaa0-425a-b378-fe2bc7e3a9ce" UUID_SUB="61a2f8bf-8cec-4bbc-b426-cb1aa226d027" BLOCK_SIZE="4096" TYPE="btrfs" PARTUUID="98d3521c-18b9-45e0-a5b2-b817323f8e89"
/dev/sda1: UUID="6E4A-5BD5" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="EFI System Partition" PARTUUID="371effc8-5c7b-4838-9d9e-ee22d9d7ab55"
/dev/zram0: LABEL="zram0" UUID="1f5a53e0-6657-447b-958d-86e84482d829" TYPE="swap"

Using the df command

The df command with the -T option will display details for file systems in the format shown below.

$ df -T
Filesystem     Type     1K-blocks    Used Available Use% Mounted on
devtmpfs       devtmpfs      4096       0      4096   0% /dev
tmpfs          tmpfs      1934144       0   1934144   0% /dev/shm
tmpfs          tmpfs       773660    1596    772064   1% /run
/dev/sda3      btrfs     13974528 4447900   8879700  34% /
tmpfs          tmpfs      1934148      16   1934132   1% /tmp
/dev/sda3      btrfs     13974528 4447900   8879700  34% /home
/dev/sda2      ext4        996780  303944    624024  33% /boot
/dev/sda1      vfat        613160   17780    595380   3% /boot/efi
tmpfs          tmpfs       386828     124    386704   1% /run/user/1000

Adding the -H option alters the numbers use to make them more human-friendly.

$ df -Th
Filesystem     Type      Size  Used Avail Use% Mounted on
devtmpfs       devtmpfs  4.0M     0  4.0M   0% /dev
tmpfs          tmpfs     1.9G     0  1.9G   0% /dev/shm
tmpfs          tmpfs     756M  1.6M  754M   1% /run
/dev/sda3      btrfs      14G  4.3G  8.5G  34% /
tmpfs          tmpfs     1.9G   16K  1.9G   1% /tmp
/dev/sda3      btrfs      14G  4.3G  8.5G  34% /home
/dev/sda2      ext4      974M  297M  610M  33% /boot
/dev/sda1      vfat      599M   18M  582M   3% /boot/efi
tmpfs          tmpfs     378M  124K  378M   1% /run/user/1000

Using the mount command

The mount command displays file system types along with a lot of additional information. The command below ensures that only details about disk devices are included in the output.

$ mount | grep ^/dev
/dev/sda3 on / type btrfs (rw,relatime,seclabel,compress=zstd:1,ssd,discard=async,space_cache=v2,subvolid=257,subvol=/root)
/dev/sda3 on /home type btrfs (rw,relatime,seclabel,compress=zstd:1,ssd,discard=async,space_cache=v2,subvolid=256,subvol=/home)
/dev/sda2 on /boot type ext4 (rw,relatime,seclabel)
/dev/sda1 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=ascii,shortname=winnt,errors=remount-ro)

Using fsck

The fsck command with the -N option will display file system types without performing a file system check as the command normally would.

$ fsck -N /dev/sda1
fsck from util-linux 2.38.1
[/usr/sbin/fsck.vfat (1) -- /boot/efi] fsck.vfat /dev/sda1
$ fsck -N /dev/sda3
fsck from util-linux 2.38.1
[/usr/sbin/fsck.btrfs (1) -- /] fsck.btrfs /dev/sda3

Using the file command

The file command as shown below will display the file system type along with the device label, sector size and other details.

$ sudo file -sL /dev/sda3
/dev/sda3: BTRFS Filesystem label "fedora_localhost-live", sectorsize 4096, nodesize 16384, leafsize 16384, UUID=d961ea75-eaa0-425a-b378-fe2bc7e3a9ce, 4340412416/14309916672 bytes used, 1 devices

Examining /etc/fstab

You can also retrieve information on file system types by looking at the /etc/fstab file.

$ cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Sat Jan 28 20:15:39 2023
#
# Accessible filesystems, by reference, are maintained under '/dev/disk/'.
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.
#
# After editing this file, run 'systemctl daemon-reload' to update systemd
# units generated from this file.
#
UUID=d961ea75-eaa0-425a-b378-fe2bc7e3a9ce /                       btrfs   subvol=root,compress=zstd:1 0 0
UUID=444b22ab-9206-4f97-b1c3-b8832d294401 /boot                   ext4    defaults        1 2
UUID=6E4A-5BD5          /boot/efi               vfat    umask=0077,shortname=winnt 0 2
UUID=d961ea75-eaa0-425a-b378-fe2bc7e3a9ce /home                   btrfs   subvol=home,compress=zstd:1 0

An easier option would be to use a command like what is shown below and limit the output to just the mount point and file system types.

$ cat /etc/fstab | grep -v ^# | awk ‘{print $2,$3}’
/ btrfs
/boot ext4
/boot/efi vfat
/home btrfs

Wrap-up

There are so many Linux commands ready to provide details on file system types that choosing a favorite or two and setting them up as aliases might be a good idea!