The du (disk usage) is the command used in Linux to check the directory size including its other contents as well as the size of individual files.
When files and directories started consuming a large amount of disk space on your hard disks then du is the best command to tell which directories or files causing this.
In this tutorial, we learn how to use du command in Linux to check disk usage (files or directories).
Du command & Syntax
The following line shows the syntax of du command:
du [options] [file or directory name]
By default, without any options, it displays the disk usage of the given file or directory and for each of the subdirectories in bytes. If no file or directory name mentioned then du commad display disk usage of the current working directory.
# du /boot 2508 /boot/grub2/fonts 3068 /boot/grub2/i386-pc 5592 /boot/grub2 4 /boot/efi/EFI/centos 8 /boot/efi/EFI 12 /boot/efi 16 /boot/loader/entries 20 /boot/loader 152440 /boot
Du command with -a option prints the disk usage of all the files within the directory.
# du -a /boot 7920 /boot/vmlinuz-4.18.0-147.5.1.el8_1.x86_64 3752 /boot/System.map-4.18.0-147.5.1.el8_1.x86_64 4 /boot/grub2/device.map 4 /boot/grub2/grub.cfg 4 /boot/grub2/grubenv 2504 /boot/grub2/fonts/unicode.pf2 2508 /boot/grub2/fonts 8 /boot/grub2/i386-pc/cs5536.mod 4 /boot/grub2/i386-pc/gcry_rsa.mod 8 /boot/grub2/i386-pc/lsacpi.mod 52 /boot/grub2/i386-pc/gcry_camellia.mod 4 /boot/grub2/i386-pc/cpio_be.mod ...... 152440 /boot
You can see that it prints the total size at the end of the command where '152440' is the total size (in bytes) of '/boot' directory.
Get total size of specified directory
To display the total size of a specified directory you have to use -s option but will not report subdirectories. The following example, it shows the total size of '/boot' directory.
# du -s /boot 152440 /boot
You can print total disk usage from multiple directories as follows:
# du -s /boot /var 152440 /boot 332168 /var
Human readable format
So far we see the disk size was showing in bytes that is not much human-readable format. In order to print the output in kilobyte (K), megabyte (M) and gigabyte (G) we have to use -h option.
# du -h /boot 2.5M /boot/grub2/fonts 3.0M /boot/grub2/i386-pc 5.5M /boot/grub2 4.0K /boot/efi/EFI/centos 8.0K /boot/efi/EFI 12K /boot/efi 16K /boot/loader/entries 20K /boot/loader 149M /boot
The --si option is like -h option but it uses powers of 1000 instead of 1024.
# du --si /boot 2.6M /boot/grub2/fonts 3.2M /boot/grub2/i386-pc 5.8M /boot/grub2 4.1k /boot/efi/EFI/centos 8.2k /boot/efi/EFI 13k /boot/efi 17k /boot/loader/entries 21k /boot/loader 157M /boot
To get the total size of a specified directory in a human-readable format which is very commonly used du command, use the following command:
# du -sh /boot 149M /boot
Combine grand total size
This is very useful when you like to combine the total size on multiple directories. The following example du command combine (-c) the total disk size of specified (-s) '/boot' and '/var' directory and print at the last line in human-readable format (-h):
# du -csh /boot/ /var 149M /boot/ 317M /var 466M total
Display individual size of all files and directories
Using wildcard (*) we can print the individual size of each file and directories and then combine total size to print in the last line.
# du -csh /boot/* 184K /boot/config-4.18.0-147.5.1.el8_1.x86_64 180K /boot/config-4.18.0-80.7.1.el8_0.x86_64 12K /boot/efi 0 /boot/grub 5.5M /boot/grub2 53M /boot/initramfs-0-rescue-3e729c2d7c094902af0333ce40564ffe.img 23M /boot/initramfs-4.18.0-147.5.1.el8_1.x86_64.img 23M /boot/initramfs-4.18.0-80.7.1.el8_0.x86_64.img 16M /boot/initramfs-4.18.0-80.7.1.el8_0.x86_64kdump.img 20K /boot/loader 3.7M /boot/System.map-4.18.0-147.5.1.el8_1.x86_64 3.6M /boot/System.map-4.18.0-80.7.1.el8_0.x86_64 7.6M /boot/vmlinuz-0-rescue-3e729c2d7c094902af0333ce40564ffe 7.8M /boot/vmlinuz-4.18.0-147.5.1.el8_1.x86_64 7.6M /boot/vmlinuz-4.18.0-80.7.1.el8_0.x86_64 149M total
Du command with Pattern matching
Using du command you can perform pattern matching. In the following command it shows how to find disk size of all directories starting with 'bo'.
# du -sch /bo* 149M /boot 217M /bootstrap 366M total
Using du command to get Apparent size
The --apparent-size option prints apparent sizes (actual amount of data in the file) rather than disk usage.
# du --apparent-size /boot 2505 /boot/grub2/fonts 2544 /boot/grub2/i386-pc 5057 /boot/grub2 4 /boot/efi/EFI/centos 8 /boot/efi/EFI 12 /boot/efi 6 /boot/loader/entries 10 /boot/loader 151852 /boot
Check directory size which include hard links
Using the -l or --count-links option, the sizes are counted many times if hard linked. By default, the hard links are not displayed.
For example
# ls -li total 648 755150 -rw-r--r-- 1 root root 4719 Apr 19 00:46 file1 755152 -rw-r--r-- 2 root root 312519 Apr 19 00:47 file2 755152 -rw-r--r-- 2 root root 312519 Apr 19 00:47 file2.hard 755153 lrwxrwxrwx 1 root root 19 Apr 19 00:57 file2.soft -> /etc/sysconfig/init
Here, file2.hard is the hard link for file2. Now notice the output with -l and without it.
# du -ah 4.0K ./file2.soft 316K ./file2 12K ./file1 340K . # du -ahl 4.0K ./file2.soft 316K ./file2 12K ./file1 316K ./file2.hard 656K .
The default behavior for symbolic links is not to dereference them. For dereferencing symbolic links, -L or --dereference option is used
# du -ahL 8.0K ./file2.soft 316K ./file2 12K ./file1 344K .
(Note that size for file2.soft has changed now)
The -P or --no-dereference option does not dereference these symlinks (which is the default behavior as stated above).
Display disk usage at 'N' level sub directories
This option instructs du command to list the subdirectories and its size to our desired depth level.
For example, the below example lists the directories to the first tier only in the current directory tree and their size. Even total consumption of space is also reported here. In case if we set the --max-depth= to zero, then du command will not list any subdirectories and it will only report the size of selected directory.
# du --max-depth=1 -h /boot/ 7.1M /boot/grub 110M /boot/
Du command to exclude files
Du command can exclude specific directory using the --exclude option. In the following example I have excluded 'grub2' directory:
# du --exclude=grub2 /boot/ 4 /boot/efi/EFI/centos 8 /boot/efi/EFI 12 /boot/efi 16 /boot/loader/entries 20 /boot/loader 146848 /boot/
Below are the two examples to show you how to exclude '*.obj' or '*.jpg' files.
# du -h –exclude=’*.obj’ # du -h –exclude=’*.jpg’
Use du command to print modification time
The modification time of files and/or directories (or of files/directories in the subdirectories) can be displayed with --time option.
# du /boot/ --time 4 2017-03-23 15:03 /boot/grub/locale 2348 2017-03-23 15:03 /boot/grub/fonts 2480 2017-03-23 15:03 /boot/grub/i386-pc 7212 2017-04-05 08:31 /boot/grub 112180 2017-04-05 08:31 /boot/
Use du with other commands
Du command can be combined with other command using pipes (|). Lets check few examples
If we want to find top 3 directories by size in the current working directory:
# du -skh * | sort -nr | head -3 386M lib 252M share 154M lib64
Display all files and directories sorted by size:
# du -sk * | sort -n 12160 libexec 37552 sbin 58900 bin 70048 src 157456 lib64 257492 share 394504 lib
Conclusion
In this tutorial, we learned how to use du command in Linux to estimate disk usage for files and directories. I hope you enjoyed reading and please leave your suggestions in the below comment section.
