Checking disk space usage with du

The du utility is used to estimate disk space usage. Its syntax is:

du [options] [file]

Basic usage

By default, du recursively lists directories and their size (in kibibytes). Typically, you want to pipe the output to sort to sort the output by the size:

# du ~example/ | sort -r | head
8348008 /home/example/
6766096 /home/example/public_html
6698220 /home/example/public_html/wp-content
6574016 /home/example/public_html/wp-content/uploads
2527828 /home/example/public_html/wp-content/uploads/2020
2196120 /home/example/public_html/wp-content/uploads/2019
1798432 /home/example/public_html/wp-content/uploads/2018
1517832 /home/example/mail
1517648 /home/example/mail/example.com
895108  /home/example/mail/example.com/info

And you can add the -h (--human-readable) option to print the directory size in units that are easier to digest:

# du -h /home/example/ | sort -hr | head
8.0G    /home/example/
6.5G    /home/example/public_html
6.4G    /home/example/public_html/wp-content
6.3G    /home/example/public_html/wp-content/uploads
2.5G    /home/example/public_html/wp-content/uploads/2020
2.1G    /home/example/public_html/wp-content/uploads/2019
1.8G    /home/example/public_html/wp-content/uploads/2018
1.5G    /home/example/mail/sistermintaka.com
1.5G    /home/example/mail
875M    /home/example/mail/example.com/info

When you look into disk space issues it is usually best to also use the -a (--all) option. This prints both directories and files. Any large backup files and/or error logs are included in the output.

And, you can also check the size of a single directory:

# du -sh /home/example
8.0G    /home/example

Advanced options

The -c (--total) option adds a grand total to the output. You can use that to, say, add up the total disk space usage of two directories:

# du -shc \
/home/example/public_html/wp-content/uploads/2018 \
/home/example/public_html/wp-content/uploads/2019
1.8G    /home/example/public_html/wp-content/uploads/2018
2.1G    /home/example/public_html/wp-content/uploads/2019
3.9G    total

Using du for large directories

If you run du on a very large directory then you may want to limit how far the utility traverses into the directory tree. The -d (--max-depth) option does just that. For instance, you can use --max-depth=1 to list the size of all directories in /home/example:

# du --max-depth=1 -h ~example| sort -hr | head
8.0G    /home/example
6.5G    /home/example/public_html
1.5G    /home/example/mail
32M     /home/example/logs
16M     /home/example/tmp
6.5M    /home/example/.cagefs
6.4M    /home/example/etc
1.6M    /home/example/.cphorde
748K    /home/example/.cpanel
80K     /home/example/ssl

The --exclude option excludes certain directories. This is particularly useful when you run du on a server’s root directory. On cPanel servers, for instance, you can safely exclude the following directories:

• /proc
• /sys
• /run
• /home/virtfs
• /usr/share/cagefs-skeleton/proc

Excluding these directories makes du faster and it prevents the output includes junk data.

# du -h / \
--exclude=/proc \
--exclude=/sys \
--exclude=/run \
--exclude=/home/virtfs \
--exclude=/usr/share/cagefs-skeleton/proc \
| sort -hr \
| head -50