正如标题所述，我的“/”分区中的磁盘空间为 97%，这是在删除了 GB 的文件之后。我正在运行 Ubuntu 18.04.2 LTS。
运行后df -Th，我得到以下输出：
Filesystem Type Size Used Avail Use% Mounted on
udev devtmpfs 3.9G 0 3.9G 0% /dev
tmpfs tmpfs 787M 3.2M 784M 1% /run
/dev/sda2 ext4 102G 94G 3.1G 97% /
tmpfs tmpfs 3.9G 0 3.9G 0% /dev/shm
tmpfs tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
/dev/loop0 squashfs 3.8M 3.8M 0 100% /snap/gnome-system-monitor/100
/dev/loop3 squashfs 55M 55M 0 100% /snap/core18/1055
/dev/loop1 squashfs 15M 15M 0 100% /snap/gnome-characters/292
/dev/loop2 squashfs 141M 141M 0 100% /snap/gnome-3-26-1604/88
/dev/loop4 squashfs 2.3M 2.3M 0 100% /snap/gnome-calculator/260
/dev/loop5 squashfs 43M 43M 0 100% /snap/gtk-common-themes/1313
/dev/loop8 squashfs 15M 15M 0 100% /snap/gnome-characters/296
/dev/loop6 squashfs 4.2M 4.2M 0 100% /snap/gnome-calculator/352
/dev/loop7 squashfs 15M 15M 0 100% /snap/gnome-logs/45
/dev/loop11 squashfs 1.0M 1.0M 0 100% /snap/gnome-logs/61
/dev/loop9 squashfs 1.0M 1.0M 0 100% /snap/gnome-logs/57
/dev/loop10 squashfs 150M 150M 0 100% /snap/gnome-3-28-1804/63
/dev/loop12 squashfs 89M 89M 0 100% /snap/core/7169
/dev/loop13 squashfs 4.2M 4.2M 0 100% /snap/gnome-calculator/406
/dev/loop14 squashfs 150M 150M 0 100% /snap/gnome-3-28-1804/67
/dev/loop16 squashfs 8.5M 8.5M 0 100% /snap/canonical-livepatch/81
/dev/loop15 squashfs 8.5M 8.5M 0 100% /snap/canonical-livepatch/77
/dev/loop18 squashfs 89M 89M 0 100% /snap/core/7270
/dev/loop17 squashfs 36M 36M 0 100% /snap/gtk-common-themes/1198
/dev/loop19 squashfs 3.8M 3.8M 0 100% /snap/gnome-system-monitor/95
/dev/loop20 squashfs 141M 141M 0 100% /snap/gnome-3-26-1604/90
/dev/loop21 squashfs 55M 55M 0 100% /snap/core18/1066
/dev/sdb ext4 1.8T 1.3T 430G 76% /mnt/Plex
/dev/sdc ext4 3.6T 89M 3.4T 1% /mnt/Plex2
/dev/sda1 vfat 511M 6.1M 505M 2% /boot/efi
tmpfs tmpfs 787M 16K 787M 1% /run/user/128
tmpfs tmpfs 787M 0 787M 0% /run/user/1000
之后，我运行sudo du --max-depth=1 -axh | sort -n得到以下结果：
0 ./initrd.img
0 ./initrd.img.old
0 ./vmlinuz
0 ./vmlinuz.old
3.8G ./usr
4.0K ./cdrom
4.0K ./lib64
4.0K ./srv
4.8G ./var
8.0K ./media
8.0K ./mnt
11G .
12M ./sbin
13M ./bin
16K ./lost+found
16M ./etc
52K ./snap
100K ./tmp
107M ./boot
203M ./opt
296K ./root
560M ./home
846M ./lib
我在其他几个论坛上看到，lsof 中可能有一些文件尚未释放。因此我运行了sudo lsof | grep deleted以下命令：
mysqld 1128 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1163 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1163 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1163 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1163 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1163 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1164 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1164 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1164 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1164 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1164 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1165 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1165 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1165 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1165 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1165 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1166 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1166 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1166 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1166 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1166 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1167 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1167 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1167 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1167 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1167 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1168 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1168 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1168 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1168 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1168 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1169 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1169 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1169 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1169 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1169 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1170 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1170 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1170 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1170 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1170 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1171 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1171 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1171 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1171 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1171 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1172 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1172 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1172 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1172 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1172 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1173 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1173 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1173 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1173 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1173 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1174 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1174 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1174 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1174 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1174 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1206 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1206 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1206 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1206 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1206 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1207 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1207 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1207 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1207 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1207 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1208 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1208 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1208 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1208 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1208 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1209 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1209 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1209 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1209 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1209 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1210 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1210 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1210 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1210 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1210 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1211 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1211 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1211 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1211 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1211 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1212 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1212 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1212 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1212 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1212 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1214 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1214 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1214 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1214 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1214 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1215 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1215 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1215 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1215 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1215 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1216 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1216 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1216 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1216 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1216 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1217 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1217 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1217 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1217 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1217 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1218 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1218 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1218 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1218 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1218 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1225 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1225 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1225 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1225 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1225 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
mysqld 1128 1226 mysql 5u REG 8,2 0 3014658 /tmp/ibbG3efy (deleted)
mysqld 1128 1226 mysql 6u REG 8,2 0 3014659 /tmp/ib58jSsO (deleted)
mysqld 1128 1226 mysql 7u REG 8,2 0 3014660 /tmp/ib9uQvG4 (deleted)
mysqld 1128 1226 mysql 8u REG 8,2 0 3014661 /tmp/ibPox2aB (deleted)
mysqld 1128 1226 mysql 12u REG 8,2 0 3014662 /tmp/ibl6rfCR (deleted)
apache2 1176 root 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
apache2 1220 www-data 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
apache2 1221 www-data 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
apache2 1222 www-data 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
apache2 1223 www-data 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
apache2 1224 www-data 9u REG 8,2 0 3014663 /tmp/.ZendSem.zhgjQN (deleted)
pulseaudi 1593 gdm 6u REG 0,5 67108864 33974 /memfd:pulseaudio (deleted)
null-sink 1593 1598 gdm 6u REG 0,5 67108864 33974 /memfd:pulseaudio (deleted)
我似乎找不到丢失的~83GB 在哪里，除非我完全错过了什么东西，而这完全有可能。
GUI 版本。左上角显示主分区有 8.8 GB / 111 GB 可用空间。底部显示 3.3 GB / 109.1 GB 可用空间。最后，右上角显示根目录占用了 10.5 GB 的空间。