I have an Ubuntu 20.04 server installed on a single 8GB drive. The default installation has some "snap"s installed also. So, there are some "squashfs" file systems also reported by the df command:
# df -mT Filesystem Type 1M-blocks Used Available Use% Mounted on /dev/root ext4 7877 1837 6025 24% / devtmpfs devtmpfs 465 0 465 0% /dev tmpfs tmpfs 477 0 477 0% /dev/shm tmpfs tmpfs 96 1 95 1% /run tmpfs tmpfs 5 0 5 0% /run/lock tmpfs tmpfs 477 0 477 0% /sys/fs/cgroup /dev/loop0 squashfs 18 18 0 100% /snap/amazon-ssm-agent/1566 /dev/loop1 squashfs 94 94 0 100% /snap/core/9066 /dev/loop2 squashfs 55 55 0 100% /snap/core18/1705 /dev/loop3 squashfs 69 69 0 100% /snap/lxd/14804 /dev/loop4 squashfs 70 70 0 100% /snap/lxd/14890 /dev/loop5 squashfs 55 55 0 100% /snap/core18/1754 tmpfs tmpfs 96 0 96 0% /run/user/1000 As you see, there is only 1837MB of data stored in the (only) disk.
Now, I am trying the list that disk usage for each directory present under root (/) using the following command:
# du -smc /* 2>/dev/null 0 /bin 48 /boot 0 /dev 8 /etc 1 /home 0 /lib 0 /lib32 0 /lib64 0 /libx32 1 /lost+found 1 /media 1 /mnt 1 /opt 0 /proc 1 /root 1 /run 0 /sbin 1116 /snap 1 /srv 0 /sys 1 /tmp 1166 /usr 601 /var 2938 total The output shows a large amount of disk space used by the /snap directory, which of course is not true.
What is the correct way to count the size of files residing only on "real disk" filesystems? Adding the option -x to du does not make me feel comfortable, because in the future I may have another "real disk" filesystem mounted under /home for example and I do want that to be counted in du's output.
2 Answers
Unlike df, as far as I know du does not provide a --exclude-type to skip particular filesystem types. However you could exclude specific top level directories by glob pattern:
du -smc --exclude=/snap /* 2>/dev/null or (to exclude ephemeral filesystems as well) and assuming your shell supports brace expansion:
du -smc --exclude=/{proc,run,sys,snap} /* 2>/dev/null You have to correctly use du's arguments. Something like:
du --one-file-system -smc /* --exclude=/snap 2> /dev/null For reference use man du locally or online.
