From the qu manpage: The qu utility displays the file system block usage for each directory in the file hierarchy rooted in each directory argument owned by the current process owner (or 'user' if specified). If no directory is specified, the block usage of the hierarchy rooted in the current directory usage is displayed. Usage is only calculated for files and directories owned by the process owner (i.e., you), making this useful for calculating real quota usage (hence qu). What this means is that qu can show you where all your disk space went. Consider this scenario: you log in one morning to find you're way over your disk quota. server% quota Disk quotas for user server (uid 1234): Filesystem blocks quota limit grace ... /usr 218783* 204800 225280 7days ... How do you track down where all your space went? You know that your logs are rotated every night, so that's not the problem. You've tried du but du shows you all disk space used, even by root, and does not take into account hard linked files. Let's try qu at our shell prompt: % qu Disk Usage for /usr/home/server/ Disk blocks Directory Path =========== ============== 65 / 3 /.cpan/ 292 /.cpan/CPAN/ 11164 /.cpan/build/ 2991 /.cpan/sources/ 1 /.ssh/ 2 /Mail/ 319 /checkbot-1.64/ 65 /checkbot-1.64/blib/ 292 /etc/ 1 /etc/.restore/ 24 /formmail/ 3 /ftp/ 5722 /ftp/upload/ 122 /tmp/ 10 /usr/ 90921 /usr/home/ 2 /usr/lib/ 1 /usr/libexec/ 104712 /usr/local/ 9 /usr/share/ 5 /var/ 1857 /var/log/ 6 /var/mail/ 8 /var/run/ 1 /var/spool/ Blocks: 218598 Total Blocks: 218598 Hmmm... let's try that again: server% qu --sort=blocks_reverse Disk Usage for /usr/home/server/ Disk blocks Directory Path =========== ============== 104712 /usr/local/ 90921 /usr/home/ 11164 /.cpan/build/ 5722 /ftp/upload/ 2991 /.cpan/sources/ 1857 /var/log/ 319 /checkbot-1.64/ 292 /.cpan/CPAN/ 292 /etc/ 122 /tmp/ 65 / 65 /checkbot-1.64/blib/ 24 /formmail/ 10 /usr/ 9 /usr/share/ 8 /var/run/ 6 /var/mail/ 5 /var/ 3 /.cpan/ 3 /ftp/ 2 /Mail/ 2 /usr/lib/ 1 /.ssh/ 1 /etc/.restore/ 1 /usr/libexec.foo/ 1 /var/spool/ Blocks: 218598 Total Blocks: 218598 Looks like I've got two directories that might be bigger than I want. 100 megs for ~/usr/local seems about right, ~/usr/home seems fishy. Just to make sure about ~/usr/local, let's see where that space is really going: server% qu --sort=blocks_reverse --levels=1 /usr/local Disk Usage for /usr/home/server/usr/local/ Disk blocks Directory Path =========== ============== 31424 /pgsql-7.1.2/ 18801 /mysql.old/ 15728 /etc/ 10353 /mysql-3.23.41/ 8676 /lib/ 2905 /man/ 2893 /curl-7.7.1/ 2192 /curl-7.8/ 1878 /mailman/ 1854 /analog-5.03/ 1791 /urchin3309d/ 1556 /analog-5.01/ 1040 /bin/ 925 /majordomo-1.94.5/ 703 /awstats-2.23q/ 669 /expat-1.95.1/ 577 /sendmail/ 347 /swish-e-2.0.5/ 312 /swish++/ 34 /frontpage/ 26 / 26 /include/ 3 /libexec/ Blocks: 104713 Total Blocks: 104713 Nothing out of the ordinary there. Let's check that big home directory we saw earlier: server% qu --sort=blocks_reverse --levels=1 /usr/home Disk Usage for /usr/home/server/usr/home/ Disk blocks Directory Path =========== ============== 80872 /foo/ 5505 /bob/ 4541 /joe/ 4 / Blocks: 90922 Total Blocks: 90922 Ouch! The 'foo' directory is much bigger than I had thought. Let's see what's going on there: server% cd usr/home/foo server% ls -l total 80872 -rw-r--r-- 1 server vuser 31603990 Aug 27 06:28 bar.log -rw-r--r-- 1 server vuser 51136330 Aug 27 06:28 foo.log So! It looks like some logs that I had forgotten about. Now I can simply: server% rm *.log server% quota Disk quotas for user server (uid 1234): Filesystem blocks quota limit grace ... /usr 137911 204800 225280 ... and I'm back in the saddle again. To find out more about qu type 'man qu' at your shell prompt.