Finding out sizes of files and directories in Linux is done using the du command, which estimates their disk space usage. The du command can be used with options that allow you to customize the results you get.
Commands can also be combined with each other so the second command filters the results output by the first command. So to find directories that are larger than 1GB you can run this command:
du -h --max-depth=1 / | grep '[0-9]G\>'
The -h option displays the sizes in a more human readable format, in gigabytes rather than kilobytes. The –max-depth=1 option makes it display the sizes of only the directories immediately within the specified path, in this case the root path /, which in Linux includes directories like /home, /usr, /bin, /var, and so on. If we were to specify 2 it would go a level further and also look into directories like /home/user, /usr/bin, /var/log, etc.
The | sign is the pipe sign that allows combining the first command with the next command, in this case grep, which is used for searching through text output for the specified strings, which can be specified through regular expressions. So the grep '[0-9]G>' searches through the du output and displays only the files that are larger than 1GB.
Here's another example of this command, but with –max-depth=1 being shortened to -d 1, which works the same, and checking the /var directory instead of the root / directory.
du -h -d 1 /var | grep '[0-9]G\>'
This single command is all you need for this task, but there's an even shorter one that works well too. You can use the built in -t or –threshold option of the du command like this:
du -h -d 1 -t 1G /
It will display first level directories larger than 1GB within the root / path, just like the first command. If you want it to display all directories, not just first level, just leave out the -d 1 option.
Finally, as a bonus, you can sort the results from largest to smallest by piping in the sort command:
du -h -d 1 -t 1G / | sort -hr
You can also sort the first command like this too, in which case you're combining the three commands into one:
du -h --max-depth=1 / | grep '[0-9]G\>' | sort -hr
Those are some of the ways you find directories larger than 1GB, or any other size you desire for that matter. Just switch 1G to 2G or 500M and so on.