How to check free disk space

To check and analyze free disk space on Linux, you can use the built-in utilities as df and du:

The df utility displays information about the total, free, and used memory space of file systems on the disk.
The du utility displays the size of files and directories.

With the df -h command, you can see the overall picture: how much free space is left and on which disk partition.

Example output:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           392M  1.5M  391M   1% /run
/dev/vda2        15G   12G  2.4G  84% /
tmpfs           2.0G  1.1M  2.0G   1% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           392M   12K  392M   1% /run/user/0

As a rule, only the partition where the root partition / is mounted needs to be analyzed. In our case, it is /dev/vda2. The example shows:

the total size is 15 GB;
12 GB occupied;
2.4 GB free.

In total, 84% of the partition is occupied.

To analyze the occupied space, use the du -sh command, specifying the path to the directory or file. For example, you can view the size of the directory located at /var/www/:

# du -sh /var/www/
659M	/var/www/

To view the size of files and directories inside, you can use the -dX switch, where X is the nesting depth of the view. For example, you can find out the size of files and directories inside /var/www/:

# du -h -d1 /var/www/ | sort
4.0K	/var/www/php-fpm
520K	/var/www/testuser
400K	/var/www/mover
568K	/var/www/php-bin-isp-php84
324K	/var/www/php-bin-isp-php73
4.0K	/var/www/httpd-logs
576K	/var/www/d-suetin
504K	/var/www/php-bin-isp-php83
20K	/var/www/html
472K	/var/www/usertest
3.6M	/var/www/df
340K	/var/www/php-bin-isp-php56
352K	/var/www/php-bin-isp-php74
340K	/var/www/php-bin-isp-php52
64K	/var/www/usr1
53M	/var/www/isimp
419M	/var/www/www-root
200K	/var/www/php-bin
180M	/var/www/importdbtest
128K	/var/www/httpd-cert
72K	/var/www/prefix
659M	/var/www/

To view the size of files and directories in subdirectories, increase the value of the switch, for example -d3.

Each analysis and its results are unique, but there are directories that are most often large:

User files of the ispmanager 6 panel at /var/www/USERNAME/
Log files of the ispmanager 6 panel at /usr/local/mgr5/var/logs/
System log files at /var/log/
DBMS binary logs at /var/log/mysql or /var/log/mariadb with the name in the format binlog.00001.