How to display btrfs subvolume tree?

Question

Is there a way to make a btrfs subvolume tree like what is shown below? (Only subvolumes - no regular directories or files.)

# tree /mnt/1
/mnt/1
├── a
├── snapshot
│ ├── a
│ └── subv
└── subv
 └── b

This example is created from a "sample" btrfs with no regular directories or files.
tree <mountpoint> shows all directories and files, not just the subvolumes. Using the -d option shows only directories, which is better, but still shows non-subvolume directories.

So, on an installed system, you get:

# tree /
/
├── bin -> usr/bin
├── boot
│  ├── grub
│  │  ├── fonts
│  │  │  └── unicode.pf2
│  │  ├── grub.cfg
│  │  ├── grub.cfg.example
│  │  ├── grubenv
│  │  ├── i386-pc
│  │  │  ├── 915resolution.mod
│  │  │  ├── acpi.mod
│  │  │  ├── adler32.mod
│  │  │  ├── affs.mod
... <over 242,000 lines snipped>

• Celada: How about tree -x? It's not exactly what you asked for, but it may suit your purpose.
• user1902689: btrfs subvolume list / currently gives me 10 lines. tree -x / gives me over 108,000 lines.
• Celada: Yeah, so then that's no good :-( I guess the trouble with your requirement is the question of what such a command should show if subvolumes /a and /a/b/c exist but the intermediate /a/b is not a subvolume but a regular directory. Omit the second level in the tree? But then where would /a/z appear if /a/z were a subvolume? Or show a blank placeholder in place of /a/b which isn't a subvolume? Also seems problematic. Anyway, maybe I'm just not imaginative enough to see the solution. Good luck.
• user1902689: @Celada - When I run btrfs subvolume list /, I see ID ### gen ### top level ### path <path>. Is the top level number corresponding to the ID numbers? If so, I'd be happy for a tree generated on that basis, where top level 5 (at least on my system, indicating the "top-level" subvolumes) are shown, with recursive branches showing any subvolumes with that node's top level. I'm guessing it would probably have to be a btrfs-progs feature.
• etskinner: I'm working on putting together a script for this. So far I've populated objects of each subvolume in a btrfs file system with their children. Anyone who's interested in helping please feel free to submit a pull request.

Answer 1

See this solution. It gets the list of subvols from btrfs command, strips the paths' column only, then passes through 2 tools: 1st converts path list to hierarchically indented text, 2nd adds ascii art tree in the place of indentation.

btrfs subvol list / | cut -f9 -d' ' | sed -e 's/^/ROOT\//' | paths2indent | indent2tree

You find these 2 perl scripts here: paths2indent and indent2tree

Example subvol list:

ID 1883 top level 5 path slash
ID 2004 top level 5 path logs
ID 2005 top level 5 path dbase
ID 2006 top level 5 path sdata
ID 2007 top level 5 path users
ID 2937 top level 5 path slash/snaps/by-procedure/quota-yazzy/users
ID 2938 top level 5 path slash/snaps/by-date/2019-11-21_0100/dbase
ID 2939 top level 5 path slash/snaps/by-date/2019-11-21_0100/slash
ID 2940 top level 5 path slash/snaps/by-date/2019-11-21_0100/logs
ID 2941 top level 5 path slash/snaps/by-date/2019-11-21_0100/sdata
ID 3004 top level 5 path slash/snaps/home/2019-12-04_0600

Example output:

ROOT
├── dbase
├── slash
│ └── snaps
│ ├── by-procedure
│ │ └── quota
│ │ └── users
│ ├── by-date
│ │ └── 2019年11月21日_0100
│ │ ├── dbase
│ │ ├── slash
│ │ ├── sdata
│ │ └── logs
│ └── home
│ └── 2019年12月04日_0600
├── users
├── sdata
└── logs

EDIT: newer versions output format differ, so change cut's field number if needed (-f7 vs. -f9).

• MountainX: Can you check that this is still working? It is not working for me, even after this fix: stackoverflow.com/a/59889217/463994
• MountainX: Resolved: I just needed to change the cut parameter to -f9
• Seth: The links to your helper scripts are broken. They're here now: indent2tree paths2indent