Root partition smaller than partition size
I have Ubuntu installed on VMware. Previous user expanded the size of the partition (I believe by using GParted in boot mode). Now I get warning about free space left on root partition. Unfortunately, it shows everything is 80G except in disk usage tool.
> sudo lsblk -o NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL
NAME FSTYPE SIZE MOUNTPOINT LABEL
loop0 squashfs 132,2M /snap/1password/66
loop1 squashfs 83,3M /snap/1password/61
loop2 squashfs 4K /snap/bare/5
loop3 squashfs 10,2M /snap/canonical-livepatch/104
loop4 squashfs 55,4M /snap/core18/2128
loop5 squashfs 10,2M /snap/canonical-livepatch/105
loop6 squashfs 208,4M /snap/code/75
loop7 squashfs 13M /snap/dmd/102
loop8 squashfs 216,3M /snap/code/76
loop9 squashfs 219M /snap/gnome-3-34-1804/72
loop10 squashfs 99,3M /snap/core/11743
loop11 squashfs 55,5M /snap/core18/2074
loop12 squashfs 167M /snap/gitkraken/182
loop13 squashfs 219M /snap/gnome-3-34-1804/66
loop14 squashfs 162,9M /snap/gnome-3-28-1804/145
loop15 squashfs 65,2M /snap/gtk-common-themes/1519
loop16 squashfs 65,1M /snap/gtk-common-themes/1515
loop17 squashfs 164,8M /snap/gnome-3-28-1804/161
loop18 squashfs 7M /snap/dub/53
loop19 squashfs 32,3M /snap/snapd/13170
loop20 squashfs 346,9M /snap/wine-platform-runtime/249
loop21 squashfs 322,8M /snap/wine-platform-6-stable/8
loop22 squashfs 61,4M /snap/prospect-mail/11
loop23 squashfs 303,1M /snap/wine-platform-5-stable/16
loop24 squashfs 126,6M /snap/slack/44
loop25 squashfs 303,1M /snap/wine-platform-5-stable/18
loop26 squashfs 51M /snap/snap-store/547
loop27 squashfs 168,1M /snap/postman/147
loop28 squashfs 32,4M /snap/snapd/13270
loop29 squashfs 51M /snap/snap-store/518
loop30 squashfs 5,5M /snap/notepad-plus-plus/292
loop31 squashfs 322,8M /snap/wine-platform-6-stable/5
loop32 squashfs 5,7M /snap/notepad-plus-plus/307
loop33 squashfs 127,2M /snap/slack/46
loop34 squashfs 99,4M /snap/core/11606
loop35 squashfs 346,9M /snap/wine-platform-runtime/250
loop36 squashfs 165,9M /snap/gitkraken/183
loop37 squashfs 168,1M /snap/postman/148
loop38 squashfs 64,9M /snap/prospect-mail/16
sda 80G
├─sda1 vfat 512M /boot/efi
├─sda2 1K
├─sda5 ext4 731M /boot
└─sda6 crypto_LUKS 78,8G
└─sda6_crypt LVM2_member 78,8G
├─vgubuntu-root ext4 77,8G /
└─vgubuntu-swap_1 swap 980M [SWAP]
sr0
Looks like your partition is about 80GB but your filesystem is about 30 GB. If you are using ext4, ext3 or ext2 there is a simple way to extend the filesystem using the resize2fs command. You are using LVM so this guide below should solve your problem. You only need to do the resize2fs step but there are a number of other commands there that will help you understand the LVM setup on your machine
https://www.tecmint.com/extend-and-reduce-lvms-in-linux/
Since this is performing significant disk operations you should backup anything you cannot afford to loose.