On Thu, Nov 26, 2015 at 12:10 AM, <waltd...@waltdnes.org> wrote: > > I'll admit that my system setup is a bit unusual. A long time ago, in > a place far away, hard drives were small, compared to today's standards. > The usual unix practice of multiple seprate partitions was not feasable > for me, but I did want to keep root on its own partition. So I > compromised with a small / partition, with empty /home, /opt, /var, > /usr, and /tmp directories. Their real equivalents are bind-mounted > from a much larger partition. I just re-did my oldest machine. It has > a primary partition 1, which covers the entire hard drive. The / > partion on /dev/sda5 is approximately 500 megabytes (YES!). There's a > 3.8 gigabyte swap partion /dev/sda6, and the rest of the drive is > /dev/sda7. Here's the relevant portion of /etc/fstab... > > /dev/sda5 / ext2 noatime,async 0 1 > /dev/sda7 /home ext3 noatime,async 0 1 > /home/bindmounts/opt /opt auto bind 0 0 > /home/bindmounts/var /var auto bind 0 0 > /home/bindmounts/usr /usr auto bind 0 0 > /home/bindmounts/tmp /tmp auto bind 0 0 > /dev/sda6 none swap sw 0 0 > > ...and the output from "df"... > > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/root 495944 49416 420928 11% / > devtmpfs 10240 0 10240 0% /dev > tmpfs 310080 356 309724 1% /run > shm 1550384 0 1550384 0% /dev/shm > cgroup_root 10240 0 10240 0% /sys/fs/cgroup > /dev/sda7 476205120 292365556 159643008 65% /opt > > ...showing /dev/sda7 mounted on /opt !?!? mc (Midnight Commander) shows > 152 of 454 gigabytes free on all of /home, /opt, /var, /usr, and /tmp, > which is correct, since they're all really bindmounts from /dev/sda7. > The / partition (/dev/sda5) has 411 of 484 megabytes free. The machine > works OK, but the "df" output is a head-scratcher. I've re-booted a > couple of times, with no change.
If the same filesystem's mounted two or more times, then df shows the shortest mountpoint. In your case, /home /opt /tmp /usr /var are mounts of /dev/sda7 so /opt is shown, because it's the first mountpoint lexically-speaking. If you use "-a", then /home will be displayed too.
