How to Check Disk Space in Linux

April 13, 2020

Introduction

How much space do I have free on my Linux drive?

Managing disk space on a Linux server is an important task. For example, package manager applications notify you how much disk space will be required for an installation. For that information to be meaningful, you should know how much space your system has available.

In this tutorial, learn how to use the df command to check disk space in Linux and the du command to display file system disk space usage.

Tutorial on checking available disk space in Linux

Prerequisites

  • A Linux-based system
  • A terminal window / command line
  • A user account with sudo or root privileges

Check Linux Disk Space Using df Command

You can check your disk space simply by opening a terminal window and entering the following:

df

Command to check disk space on Linux.

The df command stands for disk free, and it shows you the amount of space taken up by different drives. By default, df displays values in 1-kilobyte blocks.

Display Usage in Megabytes and Gigabytes

You can display disk usage in a more human-readable format by adding the –h option:

df –h

This displays the size in kilobytes (K), megabytes (M), and gigabytes (G).

Command to check disk space in human-readable format of kilobytes, megabytes,and gigabytes

Understanding the Output Format

The df command lists several columns:

Filesystem         Size      Used     Avail    Use%    Mounted on

udev               210M        0        210M     0%       /dev

tmpfs              49M       1004K      48M      3%       /run

/dev/sda2          7.9G       4.3G      3.2G     58%      /

Your output may have more entries. The columns should be self-explanatory:

  • Filesystem – This is the name of each particular drive. This includes physical hard drives, logical (partitioned) drives, and virtual or temporary drives.
  • Size – The size of the filesystem.
  • Used – Amount of space used on each filesystem.
  • Avail – The amount of unused (free) space on the filesystem.
  • Use% – Shows the percent of the disk used.
  • Mounted on – This is the directory where the file system is located. This is also sometimes called a mount point.

The list of filesystems includes your physical hard drive, as well as virtual hard drives:

  • /dev/sda2 – This is your physical hard drive. It may be listed as /sda1, /sda0, or you may even have more than one. /dev stands for device.
  • udev – This is a virtual directory for the /dev directory. This is part of the Linux operating system.
  • tmpfs – You may have several of these. These are used by /run and other Linux processes as temporary filesystems for running the operating system. For example, the tmpfs /run/lock is used to create lockfiles. These are the files that prevent multiple users from changing the same file at the same time.

Display a Specific File System

The df command can be used to display a specific file system:

df –h /dev/sda2

You can also use a backslash:

df –h /

This displays the usage on your primary hard drive. Use the mount point (in the Mounted on column) to specify the drive you want to check.

Command to display the usage of a specific file system.


Note: The df command only targets a full filesystem. Even if you specify an individual directory, df will read the space of the whole drive.


Display File Systems by Type

To list all file systems by type, use the command:

df –ht ext4

This lists drives with the ext4 type, in human-readable format.

Command to list drives with the ext4 type with size and available space show

Display Size in 1000 Instead of 1024

You can display disk usage in units of 1000 instead of 1024:

du –H

This can address a point of confusion in storage technology. Hard drive manufacturers sell hard drives in sizes based on 1000 bytes = 1 kilobyte.

However, operating systems divide that space up so that 1024 bytes = 1 kilobyte. Because of this, a 1000-gigabyte hard drive ends up with roughly 930 gigabytes of usable storage.

Check Disk Space in Linux With du Command

The du command displays disk usage. This tool can display disk usage for individual directories in Linux, giving you a finer-grained view of your disk usage. Use it to display the amount of space used by your current directory:

du

Du command for displaying disk usage in Linux.

Like the df command, you can make du human-readable:

du –h

It displays a list of the contents of the current directory, and how much space they’re using. You can simplify the display with the –s option:

du –hs

This shows how much space the current directory uses.

example of how much space is left in a linux directory

To specify the directory or file, check use the following options:

du –hs /etc/kernel-img.conf
du –hs /etc

With the second command, you may have noticed a permission denied error message. This means the current user doesn’t have the privileges to access certain directories. Use the sudo command to elevate your privileges:

sudo du –hs /etc

Note: If you’re working on CentOS Linux, you may need to use the su command to switch to the root user to access protected directories.


Conclusion

You should now understand how to use df and du commands to check disk space on your Linux system. Remember, to display a complete list of options, use either df ––help or du ––help.

Check out our article on how to use fsck command to run a filesystem check as preventive maintenance or when there is an issue with your system.

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Sofija Simic
Sofija Simic is an aspiring Technical Writer at phoenixNAP. Alongside her educational background in teaching and writing, she has had a lifelong passion for information technology. She is committed to unscrambling confusing IT concepts and streamlining intricate software installations.
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