du command in Linux with examples

The `du` command in Linux is a powerful utility that allows users to analyze and report on disk usage within directories and files. Whether you’re trying to identify space-hogging directories, manage disk space efficiently, or simply gain insights into storage consumption, the du command provides valuable information. In this article, we’ll explore the du command, its basic syntax, and various examples to demonstrate its functionality.

Syntax of `du` command in Linux

The basic syntax of the du command is as follows:

du [options] [directory/file]

Here,

[options] = various flags that modify the behavior of the command

[directory/file] = the target directory or file for which disk usage information is desired. If no directory or file is specified, du will default to the current directory.

Example:

du /home/mandeep/test

Output:

44    /home/mandeep/test/data
2012    /home/mandeep/test/system design
24    /home/mandeep/test/table/sample_table/tree
28    /home/mandeep/test/table/sample_table
32    /home/mandeep/test/table
100104    /home/mandeep/test

Options available in `du` command in Linux

The du command offers a range of options that enhance its functionality. Let’s explore some commonly used options:

Options	Describe
-0, –null	end each output line with NULL
-a or –all	Displays disk usage information for all files and directories, including hidden ones.
–apparent-size	print apparent sizes, rather than disk usage
-B, –block-size=SIZE	scale sizes to SIZE before printing on console
-c or –total	Shows the total disk usage in addition to individual usage for directories and files.
-d, –max-depth=N	print total for directory only if it is N or fewer levels below command line argument
-h or –human-readable	Displays sizes in human-readable format, using units such as KB, MB, GB, etc. This option makes it easier to interpret the disk usage information.
-S, -separate-dirs	for directories, don’t include size of subdirectories
-s or –summarize	Provides a summary of the disk usage for the specified directory or file, without displaying individual usage details for subdirectories.
–time	show time of last modification of any file or directory
–exclude	Excludes specific directories or files from disk usage calculation based on patterns or names.

Pratical Example of du Command

1. `-h` option in `du` command

If we want to print sizes in human readable format(K, M, G), use -h option

du -h /home/Mandeep/test 

Output:

44K    /home/mandeep/test/data
2.0M    /home/mandeep/test/system design
24K    /home/mandeep/test/table/sample_table/tree
28K    /home/mandeep/test/table/sample_table
32K    /home/mandeep/test/table
98M    /home/mandeep/test

44K    /home/mandeep/test/data
2.0M    /home/mandeep/test/system design
24K    /home/mandeep/test/table/sample_table/tree
28K    /home/mandeep/test/table/sample_table
32K    /home/mandeep/test/table
98M    /home/mandeep/test

2. To display all files, including directories, with their sizes

Use -a option for printing all files including directories.

du -a -h /home/mandeep/test

Output: This is partial output of above command.

4.0K    /home/mandeep/test/blah1-new
4.0K    /home/mandeep/test/fbtest.py
8.0K    /home/mandeep/test/data/4.txt
4.0K    /home/mandeep/test/data/7.txt
4.0K    /home/mandeep/test/data/1.txt
4.0K    /home/mandeep/test/data/3.txt
4.0K    /home/mandeep/test/data/6.txt
4.0K    /home/mandeep/test/data/2.txt
4.0K    /home/mandeep/test/data/8.txt
8.0K    /home/mandeep/test/data/5.txt
44K    /home/mandeep/test/data
4.0K    /home/mandeep/test/notifier.py

3. To calculate the total size of a directory and its subdirectories

Use -c option to print total size

du -c -h /home/mandeep/test

Output:

44K    /home/mandeep/test/data
2.0M    /home/mandeep/test/system design
24K    /home/mandeep/test/table/sample_table/tree
28K    /home/mandeep/test/table/sample_table
32K    /home/mandeep/test/table
98M    /home/mandeep/test
98M    total

`-d` option in `du` command

To print sizes to particular level, use -d option with level no.

du -d 1 /home/mandeep/test

Output:

44    /home/mandeep/test/data
2012    /home/mandeep/test/system design
32    /home/mandeep/test/table
100104    /home/mandeep/test

Now try with level 2, you will get some extra directories

du -d 2 /home/mandeep/test

Output:

44    /home/mandeep/test/data
2012    /home/mandeep/test/system design
28    /home/mandeep/test/table/sample_table
32    /home/mandeep/test/table
100104    /home/mandeep/test

4. To obtain the disk usage summary for a directory

Get summary of file system using -s option

du -s /home/mandeep/test

Output:

100104    /home/mandeep/test

5. To view the timestamp of the last modification of files and directories

Get the timestamp of last modified using –time option

du --time -h /home/mandeep/test

Output:

44K    2018-01-14 22:22    /home/mandeep/test/data
2.0M    2017-12-24 23:06    /home/mandeep/test/system design
24K    2017-12-30 10:20    /home/mandeep/test/table/sample_table/tree
28K    2017-12-30 10:20    /home/mandeep/test/table/sample_table
32K    2017-12-30 10:20    /home/mandeep/test/table
98M    2018-02-02 17:32    /home/mandeep/test

Frequently Asked Question

1. What is the du command in Linux, and how does it differ from the df command?

The du command in Linux is used to estimate file space usage. It displays the sizes of directories and files, helping users identify which directories are consuming the most disk space. Unlike df, which shows information about mounted file systems, du focuses on individual files and directories within those file systems.

2. How can I use the du command to find the largest directories on my system?

To find the largest directories, you can use the du command with the --max-depth option.

For example:

du --max-depth=1 /path

It will display the sizes of the immediate subdirectories under the specified path.

3. Is there a way to display disk usage in a human-readable format with the du command?

Yes, the du command supports the -h option to display sizes in a human-readable format (e.g., KB, MB, GB).

For instance:

du -h /path

It will provide a more readable output.

4. Can I use the du command to find large files within a directory?

Absolutely. You can combine the `find` command with du to identify large files.

For example:

find /path -type f -exec du -h {} + | sort -rh | head -n 10

It will list the top 10 largest files under the specified path.

5. How do I exclude certain directories or files from the du command output?

To exclude specific directories, use the --exclude option with the du command.

For example:

du -h --exclude=/path/to/exclude /path

It will display disk usage for the specified path while excluding the specified directory.

Conclusion

In this article we have discussed the `du` command in Linux which provides us essential insights into file and directory space usage, enabling users to effectively manage their storage. We also discussed the variety of options available. Overall, we can say that mastering `du` command and its options, a user can efficiently analyze disk usage, identify storage areas, and optimize their system’s storage utilization.