Disk usage check in linux

Classic SysAdmin: How to Check Disk Space on Linux from the Command Line

This is a classic article written by Jack Wallen from the Linux.com archives. For more great SysAdmin tips and techniques check out our free intro to Linux course.

Quick question: How much space do you have left on your drives? A little or a lot? Follow up question: Do you know how to find out? If you happen to use a GUI desktop (e.g., GNOME, KDE, Mate, Pantheon, etc.), the task is probably pretty simple. But what if you’re looking at a headless server, with no GUI? Do you need to install tools for the task? The answer is a resounding no. All the necessary bits are already in place to help you find out exactly how much space remains on your drives. In fact, you have two very easy-to-use options at the ready.

In this article, I’ll demonstrate these tools. I’ll be using Elementary OS, which also includes a GUI option, but we’re going to limit ourselves to the command line. The good news is these command-line tools are readily available for every Linux distribution. On my testing system, there are a number of attached drives (both internal and external). The commands used are agnostic to where a drive is plugged in; they only care that the drive is mounted and visible to the operating system.

With that said, let’s take a look at the tools.

df

The df command is the tool I first used to discover drive space on Linux, way back in the 1990s. It’s very simple in both usage and reporting. To this day, df is my go-to command for this task. This command has a few switches but, for basic reporting, you really only need one. That command is df -H. The -H switch is for human-readable format. The output of df -H will report how much space is used, available, percentage used, and the mount point of every disk attached to your system (Figure 1).

What if your list of drives is exceedingly long and you just want to view the space used on a single drive? With df, that is possible. Let’s take a look at how much space has been used up on our primary drive, located at /dev/sda1. To do that, issue the command:

The output will be limited to that one drive (Figure 2).

You can also limit the reported fields shown in the df output. Available fields are:

• source — the file system source
• size — total number of blocks
• used — spaced used on a drive
• avail — space available on a drive
• pcent — percent of used space, divided by total size
• target — mount point of a drive

Let’s display the output of all our drives, showing only the size, used, and avail (or availability) fields. The command for this would be:

The output of this command is quite easy to read (Figure 3).

The only caveat here is that we don’t know the source of the output, so we’d want to include source like so:

df -H --output=source,size,used,avail

Now the output makes more sense (Figure 4).

du

Our next command is du. As you might expect, that stands for disk usage. The du command is quite different to the df command, in that it reports on directories and not drives. Because of this, you’ll want to know the names of directories to be checked. Let’s say I have a directory containing virtual machine files on my machine. That directory is /media/jack/HALEY/VIRTUALBOX. If I want to find out how much space is used by that particular directory, I’d issue the command:

du -h /media/jack/HALEY/VIRTUALBOX

The output of the above command will display the size of every file in the directory (Figure 5).

So far, this command isn’t all that helpful. What if we want to know the total usage of a particular directory? Fortunately, du can handle that task. On the same directory, the command would be:

du -sh /media/jack/HALEY/VIRTUALBOX/

Now we know how much total space the files are using up in that directory (Figure 6).

You can also use this command to see how much space is being used on all child directories of a parent, like so:

The output of this command (Figure 7) is a good way to find out what subdirectories are hogging up space on a drive.

The du command is also a great tool to use in order to see a list of directories that are using the most disk space on your system. The way to do this is by piping the output of du to two other commands: sort and head. The command to find out the top 10 directories eating space on a drive would look something like this:

du -a /media/jack | sort -n -r | head -n 10

The output would list out those directories, from largest to least offender (Figure 8).

Not as hard as you thought

Finding out how much space is being used on your Linux-attached drives is quite simple. As long as your drives are mounted to the Linux system, both df and du will do an outstanding job of reporting the necessary information. With df you can quickly see an overview of how much space is used on a disk and with du you can discover how much space is being used by specific directories. These two tools in combination should be considered must-know for every Linux administrator.

And, in case you missed it, I recently showed how to determine your memory usage on Linux. Together, these tips will go a long way toward helping you successfully manage your Linux servers.

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10 Useful du (Disk Usage) Commands to Find Disk Usage of Files and Directories

The Linux “du” (Disk Usage) is a standard Unix/Linux command, used to check the information of disk usage of files and directories on a machine.

The du command has many parameter options that can be used to get the results in many formats. The du command also displays the files and directory sizes in a recursive manner.

This article explains 10 useful “du” commands with their examples, which might help you to find out the sizes of files and directories in Linux. The information provided in this article is taken from the man pages of du command.

How to Find the Size of a Directory in Linux

1. To find out the disk usage summary of a /home/tecmint directory tree and each of its subdirectories. Enter the command as:

[[email protected]]# du /home/tecmint 40 /home/tecmint/downloads 4 /home/tecmint/.mozilla/plugins 4 /home/tecmint/.mozilla/extensions 12 /home/tecmint/.mozilla 12 /home/tecmint/.ssh 689112 /home/tecmint/Ubuntu-12.10 689360 /home/tecmint

The output of the above command displays the number of disk blocks in the /home/tecmint directory along with its sub-directories.

How to Find the Directory Size in Human Readable Format

2. Using the “-h” option with the “du” command provides results in “Human Readable Format“. This means you can see sizes in Bytes, Kilobytes, Megabytes, Gigabytes, etc.

[[email protected]]# du -h /home/tecmint 40K /home/tecmint/downloads 4.0K /home/tecmint/.mozilla/plugins 4.0K /home/tecmint/.mozilla/extensions 12K /home/tecmint/.mozilla 12K /home/tecmint/.ssh 673M /home/tecmint/Ubuntu-12.10 674M /home/tecmint

How to Find Total Size of a Directory in Linux

3. To get the summary of a grand total disk usage size of a directory uses the option “-s” as follows.

[[email protected]]# du -sh /home/tecmint 674M /home/tecmint

4. Using the “-a” flag with the “du” command displays the disk usage of all the files and directories.

[[email protected]]# du -a /home/tecmint 4 /home/tecmint/.bash_logout 12 /home/tecmint/downloads/uploadprogress-1.0.3.1.tgz 24 /home/tecmint/downloads/Phpfiles-org.tar.bz2 40 /home/tecmint/downloads 12 /home/tecmint/uploadprogress-1.0.3.1.tgz 4 /home/tecmint/.mozilla/plugins 4 /home/tecmint/.mozilla/extensions 12 /home/tecmint/.mozilla 4 /home/tecmint/.bashrc 689108 /home/tecmint/Ubuntu-12.10/ubuntu-12.10-server-i386.iso 689112 /home/tecmint/Ubuntu-12.10 689360 /home/tecmint

5. Using the “-a” flag along with “-h” displays disk usage of all files and folders in a human-readable format. The below output is easier to understand as it shows the files in Kilobytes, Megabytes, etc.

[[email protected]]# du -ah /home/tecmint 4.0K /home/tecmint/.bash_logout 12K /home/tecmint/downloads/uploadprogress-1.0.3.1.tgz 24K /home/tecmint/downloads/Phpfiles-org.tar.bz2 40K /home/tecmint/downloads 12K /home/tecmint/uploadprogress-1.0.3.1.tgz 4.0K /home/tecmint/.mozilla/plugins 4.0K /home/tecmint/.mozilla/extensions 12K /home/tecmint/.mozilla 4.0K /home/tecmint/.bashrc 673M /home/tecmint/Ubuntu-12.10/ubuntu-12.10-server-i386.iso 673M /home/tecmint/Ubuntu-12.10 674M /home/tecmint

6. Find out the disk usage of a directory tree with its subtree in Kilobyte blocks. Use the “-k” (displays size in 1024 bytes units).

[[email protected]]# du -k /home/tecmint 40 /home/tecmint/downloads 4 /home/tecmint/.mozilla/plugins 4 /home/tecmint/.mozilla/extensions 12 /home/tecmint/.mozilla 12 /home/tecmint/.ssh 689112 /home/tecmint/Ubuntu-12.10 689360 /home/tecmint

7. To get the summary of disk usage of directory tree along with its subtrees in Megabytes (MB) only. Use the option “-mh” as follows. The “-m” flag counts the blocks in MB units and “-h” stands for human-readable format.

[[email protected]]# du -mh /home/tecmint 40K /home/tecmint/downloads 4.0K /home/tecmint/.mozilla/plugins 4.0K /home/tecmint/.mozilla/extensions 12K /home/tecmint/.mozilla 12K /home/tecmint/.ssh 673M /home/tecmint/Ubuntu-12.10 674M /home/tecmint

8. The “-c” flag provides a grand total usage disk space at the last line. If your directory is taken 674MB space, then the last last two lines of the output would be.

[[email protected]]# du -ch /home/tecmint 40K /home/tecmint/downloads 4.0K /home/tecmint/.mozilla/plugins 4.0K /home/tecmint/.mozilla/extensions 12K /home/tecmint/.mozilla 12K /home/tecmint/.ssh 673M /home/tecmint/Ubuntu-12.10 674M /home/tecmint 674M total 

How to Exclude Files with du Command

9. The below command calculates and displays the disk usage of all files and directories, but excludes the files that match the given pattern. The below command excludes the “.txt” files while calculating the total size of a directory. So, this way you can exclude any file formats by using the flag “-–exclude“. See the output there is no txt files entry.

[[email protected]]# du -ah --exclude="*.txt" /home/tecmint 4.0K /home/tecmint/.bash_logout 12K /home/tecmint/downloads/uploadprogress-1.0.3.1.tgz 24K /home/tecmint/downloads/Phpfiles-org.tar.bz2 40K /home/tecmint/downloads 12K /home/tecmint/uploadprogress-1.0.3.1.tgz 4.0K /home/tecmint/.bash_history 4.0K /home/tecmint/.bash_profile 4.0K /home/tecmint/.mozilla/plugins 4.0K /home/tecmint/.mozilla/extensions 12K /home/tecmint/.mozilla 4.0K /home/tecmint/.bashrc 24K /home/tecmint/Phpfiles-org.tar.bz2 4.0K /home/tecmint/geoipupdate.sh 4.0K /home/tecmint/.zshrc 120K /home/tecmint/goaccess-0.4.2.tar.gz.1 673M /home/tecmint/Ubuntu-12.10/ubuntu-12.10-server-i386.iso 673M /home/tecmint/Ubuntu-12.10 674M /home/tecmint

How to Find Directory Usage By Modification Time

10. Display the disk usage based on a modification of time, use the flag “–time” as shown below.

[[email protected]]# du -ha --time /home/tecmint 4.0K 2012-10-12 22:32 /home/tecmint/.bash_logout 12K 2013-01-19 18:48 /home/tecmint/downloads/uploadprogress-1.0.3.1.tgz 24K 2013-01-19 18:48 /home/tecmint/downloads/Phpfiles-org.tar.bz2 40K 2013-01-19 18:48 /home/tecmint/downloads 12K 2013-01-19 18:32 /home/tecmint/uploadprogress-1.0.3.1.tgz 4.0K 2012-10-13 00:11 /home/tecmint/.bash_history 4.0K 2012-10-12 22:32 /home/tecmint/.bash_profile 0 2013-01-19 18:32 /home/tecmint/xyz.txt 0 2013-01-19 18:32 /home/tecmint/abc.txt 4.0K 2012-10-12 22:32 /home/tecmint/.mozilla/plugins 4.0K 2012-10-12 22:32 /home/tecmint/.mozilla/extensions 12K 2012-10-12 22:32 /home/tecmint/.mozilla 4.0K 2012-10-12 22:32 /home/tecmint/.bashrc 24K 2013-01-19 18:32 /home/tecmint/Phpfiles-org.tar.bz2 4.0K 2013-01-19 18:32 /home/tecmint/geoipupdate.sh 4.0K 2012-10-12 22:32 /home/tecmint/.zshrc 120K 2013-01-19 18:32 /home/tecmint/goaccess-0.4.2.tar.gz.1 673M 2013-01-19 18:51 /home/tecmint/Ubuntu-12.10/ubuntu-12.10-server-i386.iso 673M 2013-01-19 18:51 /home/tecmint/Ubuntu-12.10 674M 2013-01-19 18:52 /home/tecmint

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