How do I quickly calculate the size of a directory?

Question

I want to calculate the size of my home directory, which has a lot of sub directories.

It takes about 40 seconds to run du.
Is there a quicker way?

$ time du -sh
5.0G    .

real    0m39.676s
user    0m0.058s
sys     0m3.151s

Answer 1

A rather round about method would be to put your home directory on a separate partition that gets mounted at boot, making sure it is large enough for all your future needs.

After you've done that then the fastest way to tell how much space you are using is the df command which will show the free and used space on the partitions. df also has switches to show the information in human readable formats.

Answer 2

No, there isn't a quick way. You need to go through all subdirectories.

Answer 3

… or, thirdly, one can use disc quotas.

A variant on Mokubai's roundabout answer is to have all home directories on a dedicated volume for home directories, to enable disc quotas on that volume (and build the quota database if quotas are being added to a volume with data already on it), and to use the quota command to display how much of a user's disc quota for that volume that user has used. Those used to traditional Unices in centralized multi-user timesharing environments will find this very familiar. ☺

This really does have an advantage over du when it comes to the "How much disc space is the stuff that I own taking up?" question: If some other user slyly hardlinks one of your files — that you subsequently unlink from your home directory and think to be gone — into one of xyr own directories, that xe denies you read+execute permission for (and that hence you cannot scan with du), the disc space that it consumes will still count against your disc quota and you can detect the discrepancy.

And, of course, all the security and maintainability advantages of having a separate volume for all home directories also apply.