While I used Linux since 2014, I've never had a filesystem fill up. Mine is 93% full on an HP laptop with Mint 20 installed on a dual-boot. I've spent a few days researching with Bing and Google.

I followed the instructions from this thread, https://www.linuxquestions.org/quest...ce-4175603355/.

I've never had to delete from a filesystem that I don't work in and I really need an experienced set of eyes to help me see what's wrong and guidance to make sure I don't delete the wrong thing. Following is what I've uncovered so far. I flipped a few steps in troublshooting by accident but it's the step-by-step in the linked thread above.

Thanks in advance.

oem@nightwingnook666:~$ sudo df -h
[sudo] password for oem:
Filesystem Size Used Avail Use% Mounted on
udev 1.9G 0 1.9G 0% /dev
tmpfs 385M 1.7M 384M 1% /run
/dev/sda6 19G 16G 1.3G 93% /
tmpfs 1.9G 202M 1.7G 11% /dev/shm
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda1 260M 68M 192M 27% /boot/efi
/dev/sda7 506G 412G 69G 86% /home
tmpfs 385M 24K 385M 1% /run/user/29999

oem@nightwingnook666:~$ sudo du / | sort -rn | head
du: cannot access '/proc/5927/task/5927/fd/4': No such file or directory
du: cannot access '/proc/5927/task/5927/fdinfo/4': No such file or directory
du: cannot access '/proc/5927/fd/3': No such file or directory
du: cannot access '/proc/5927/fdinfo/3': No such file or directory
du: cannot access '/run/user/29999/doc': Permission denied
du: cannot access '/run/user/29999/gvfs': Permission denied
448462296 /
431670604 /home
431670576 /home/oem
215124392 /home/oem/Videos
154267116 /home/oem/Downloads
26963860 /home/oem/Comics
25873104 /home/oem/Downloads/Naruto Shippuden Remake Complete (1-500, all seasons) [h.264] [Dual Audio]
21977280 /home/oem/Videos/Queer As Folk US Season 4 Complete 720P AMZN WEB-DL x264 [i_c]
21894936 /home/oem/Comics/Dennis O'Neil Comics
19898012 /home/oem/Comics/Dennis O'Neil Comics/Comics

oem@nightwingnook666:~$ sudo df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
udev 482115 627 481488 1% /dev
tmpfs 492412 1106 491306 1% /run
/dev/sda6 1222992 497229 725763 41% /
tmpfs 492412 377 492035 1% /dev/shm
tmpfs 492412 5 492407 1% /run/lock
tmpfs 492412 18 492394 1% /sys/fs/cgroup
/dev/sda1 0 0 0 - /boot/efi
/dev/sda7 33742848 88042 33654806 1% /home
tmpfs 492412 60 492352 1% /run/user/29999


oem@nightwingnook666:~$ sudo mkdir /tmp/rootbind
oem@nightwingnook666:~$ sudo mount --bind / /tmp/rootbind
oem@nightwingnook666:~$ sudo du -d 1 -h /tmp/rootbind
4.1G /tmp/rootbind/var
4.0K /tmp/rootbind/cdrom
4.0K /tmp/rootbind/mnt
4.0K /tmp/rootbind/proc
19M /tmp/rootbind/bin
4.0K /tmp/rootbind/sys
44K /tmp/rootbind/media
6.1M /tmp/rootbind/lib32
32K /tmp/rootbind/timeshift
283M /tmp/rootbind/boot
2.8M /tmp/rootbind/root
22M /tmp/rootbind/sbin
4.0K /tmp/rootbind/srv
4.0K /tmp/rootbind/home
124K /tmp/rootbind/tmp
1.4G /tmp/rootbind/lib
1.9G /tmp/rootbind/opt
16K /tmp/rootbind/dev
4.0K /tmp/rootbind/lib64
8.5G /tmp/rootbind/usr
116K /tmp/rootbind/run
16K /tmp/rootbind/lost+found
30M /tmp/rootbind/etc
16G /tmp/rootbind

oem@nightwingnook666:~$ sudo du -smx /* | sort -n
du: cannot access '/proc/6159/task/6159/fd/4': No such file or directory
du: cannot access '/proc/6159/task/6159/fdinfo/4': No such file or directory
du: cannot access '/proc/6159/fd/3': No such file or directory
du: cannot access '/proc/6159/fdinfo/3': No such file or directory
0 /dev
0 /proc
0 /sys
1 /cdrom
1 /lib64
1 /lost+found
1 /media
1 /mnt
1 /srv
1 /timeshift
2 /run
3 /root
7 /lib32
19 /bin
22 /sbin
30 /etc
283 /boot
1370 /lib
1861 /opt
12740 /tmp
421544 /home

oem@nightwingnook666:~$ sudo mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,nosuid,noexec,relatime,size=1928460k,nr_inodes=482115,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,nodev,noexec,relatime,size=393932k,mode=755)
/dev/sda6 on / type ext4 (rw,relatime,errors=remount-ro)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup2 on /sys/fs/cgroup/unified type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
efivarfs on /sys/firmware/efi/efivars type efivarfs (rw,nosuid,nodev,noexec,relatime)
none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)
cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/rdma type cgroup (rw,nosuid,nodev,noexec,relatime,rdma)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=28,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=18156)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,pagesize=2M)
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)
tracefs on /sys/kernel/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)
configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
/dev/sda1 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/sda7 on /home type ext4 (rw,relatime)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,nosuid,nodev,noexec,relatime)
tmpfs on /run/user/29999 type tmpfs (rw,nosuid,nodev,relatime,size=393928k,mode=700,uid=29999,gid=29999)
gvfsd-fuse on /run/user/29999/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=29999,group_id=29999)
/dev/fuse on /run/user/29999/doc type fuse (rw,nosuid,nodev,relatime,user_id=29999,group_id=29999)
tracefs on /sys/kernel/debug/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)
/dev/sda6 on /tmp/rootbind type ext4 (rw,relatime,errors=remount-ro)

oem@nightwingnook666:~$ df -i /
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/sda6 1222992 497230 725762 41% /
oem@nightwingnook666:~$ sudo du -h --max-depth=1 /
4.1G /var
4.0K /cdrom
4.0K /mnt
du: cannot access '/proc/3728/task/3732/fdinfo/38': No such file or directory
du: cannot access '/proc/6324/task/6324/fd/4': No such file or directory
du: cannot access '/proc/6324/task/6324/fdinfo/4': No such file or directory
du: cannot access '/proc/6324/fd/3': No such file or directory
du: cannot access '/proc/6324/fdinfo/3': No such file or directory
0 /proc
19M /bin
0 /sys
44K /media
6.1M /lib32
32K /timeshift
350M /boot
2.8M /root
22M /sbin
4.0K /srv
412G /home
120K /tmp
1.4G /lib
1.9G /opt
0 /dev
4.0K /lib64
8.5G /usr
du: cannot access '/run/user/29999/doc': Permission denied
du: cannot access '/run/user/29999/gvfs': Permission denied
1.8M /run
16K /lost+found
30M /etc
428G /

Odds are that over the years you have installed some packages that are just sitting and taking up space. One place to look is in /boot for lots of old kernels. Removing them and their associated linux-header files will free up lots of space.
Just be sure to use the package management tools and not 'rm' for the clean up.

Thanks for the heads up, but the things I've learned through this and other Linux forums and websites like itsfoss.com. I've never had this many "devs," .i.e. /dev/sda6, /dev/sda7, etc. in a partition and not sure how to determine which kernels I can delete. I just had a kernel update a few days ago.
Any specific terminal line commands would help. I really like being able to check on the progress and what's going on under the hood.

How do I check boot in terminal?

Does Mint offer to delete files when you apt update and and apt upgrade?
If it does it should offer apt autoremove

It did that a few times here after a kernel update. i think it was around 360 mb or so per kernel deleted.

Edit:
https://tweakers.net/fotoalbum/image...ehJBsWCHUH.png

If you have gparted installed, it can give a great idea where are all those partitions reside.
Example here is my laptop.

Regardless of how many partitions (/dev/sda#) you have, there is only one location for kernels. Find the kernel you boot into, and keep that and the one previous, and delete the rest. You can do that with apt,using the --purge option. Also run apt clean and apt autoclean, which will clear out the old package files in the cache. This could give you a gigabyte or more. Another place that probably has lots of files is /var/log. You probably don't bother to read the logs, so removing them shouldn't be a problem. Apt autoremove might give you considerable more free space, but be very careful about that. It can remove essential packages, so make sure all the removals are acceptable. That can be hard, so I would advise erring on the side of caution there. Another possible source of excess files is erroneous copy to /media. Remove all external drives, if there are any, and check /media. There should be nothing there other than perhaps some empty directories.

your post shows that /dev/sda6 is / and /dev/sda7 is /home. You also have /dev/sda1 as the efi partition. Each is a discrete partition on /dev/sda and none of those are excess.
What I see as the real issue is that / has only 19G allocated and you have that almost full. You would need to remove something as has already been suggested or make more space available somehow.

I assume this is dual boot with windows which would account for at least 3 additional partitions in between sda1 and sda6.

Please run "sudo fdisk -l" and see exactly what other partitions are on that drive, then post that output here. It will tell you the total size of the drive, the sizes of each partition on that drive, and what that partition is.
Once you know what is there then you can decide what to do about space; remove packages, clean up extra kernels, clean up cache, adjust partition size, etc.

What do you have in /root. Your post shows "2.8M /tmp/rootbind/root" which is almost 3M and that is 2.8M more than I use.

oem@nightwingnook666:~$ sudo fdisk -l
[sudo] password for oem:
Sorry, try again.
[sudo] password for oem:
Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: WDC WD10SPZX-60Z
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 0D119515-222C-4FFE-B95C-FFB7D317F2F1

Device Start End Sectors Size Type
/dev/sda1 2048 534527 532480 260M EFI System
/dev/sda2 534528 567295 32768 16M Microsoft reserved
/dev/sda3 567296 825104383 824537088 393.2G Microsoft basic data
/dev/sda4 1951504384 1953511423 2007040 980M Windows recovery environment
/dev/sda5 825104384 832917503 7813120 3.7G Linux swap
/dev/sda6 832917504 871979007 39061504 18.6G Linux filesystem
/dev/sda7 871979008 1951504383 1079525376 514.8G Linux filesystem

Partition table entries are not in disk order.

I'm just not sure what to delete since I've never had this problem before. As I stated above, I've been researching this for the last few days and I'm pretty sure there are old kernels, but again I'm not sure what to delete.

Any guidance is greatly appreciated.

Looking at that I would suggest going into windows and see how much space is actually used there. I have a 500G disk in my laptop and when I did the dual boot install I reduced the size of the windows data partition to 100G and used the freed up space for linux - about 375G.
Looking at yours I believe that you could probably (depending on how much data you actually have in windows) use the windows disk manager to 1) defrag the drive then 2) reduce the file system and partition to about 200G. That would free up about 190G for use by linux.
Once the space is free then we can help to move part or all the linux install to a new partition with more space.

Reducing the windows partition would be the same steps as instructions tell you to follow for a new dual boot install. The rest we have to do manually.

I'll have to do that tomorrow when I'm on a more stable and faster connection, since I've been putting off updating Windows. I'll check in tomorrow with the results.

Again thanks everyone for the help so far.

Just a thought.
How critical is keeping the current install? or would a new install be acceptable?
It would be lots easier to allocate and use the new space for / with a new install.

Before deleting any filesystems, take a look at "/var/log" as sgosnell suggested. If you're not using logrotate to manage the log files under "/var/log" I'd strongly suggest looking into getting that configured so that log files don't consume too much of your root partition. Make sure you have it compressing the older log files. If you've configured some system service to provide debug information in their logs, turn that off when it's no longer needed---it can increase log file size quite a bit. Also, making "/var" a separate filesystem can help (more of a future project for you) so that "/" doesn't fill up---if "/var" fills up it's not quite the system-halting event that filling up "/" is.

HTH...

I don't think his problem has anything to do with logs, extra kernels, etc. other than as the last straw. His / partition is only 19G and is 93% full so almost anything will break that camels back. He probably cannot even do a full update with that. He also has at present no space on the HDD to move anything according to his fdisk -l output.

He has ~2GB in /opt, which is a lot for that directory. I have no idea what is there, or if it's necessary. And 4GB in /var, which isn't necessarily huge, but could include files that aren't necessary, such as cached package files and logs, among others. He could shrink /home and extend /, and that's probably the best bet long-term, but it will take time to move all the files in /home so it can be shrunk.

That could be.
But he also has ~400G in his windows partition and if that is not all needed he can easily get ~200G from there, leaving him with a great plenty for windows and a lot more space to grow/relocate his linux install. He would have almost twice what he currently has in his entire linux space in the newly unallocated space from shrinking windows.
Because of the way his partitions are located I would look at creating a new partition (/dev/sda8) in that newly freed up space to relocate /home, then expand/resize / (/dev/sda6) to use part or all of the space currently in /home (/dev/sda7). This keeps partitions contiguous and can easily be handled one step at a time. without even doing a reinstall or booting from a live USB.

I use separate partitions (filesystems) for videos etc, so it would be easy to move a bunch of videos into the new space, reducing the /home usage.
This also makes backups simpler, since I don't bother backing up videos.

You will need an extra line in the fstab file.