what mens gen and ogen in btrfs sub list / ?

["Lentes, Bernd" <bernd.lentes@helmholtz-muenchen.de>]

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Hi,

i'd like to write a script in which, beneath other stuff, the oldest snapshot(s) are deleted.
So i'm looking for a way to sort the list of the snapshots by date.
I read the manpage and stumbled across gen and ogen of snapshots.
But what does that mean and how can the values be interpreted ?
Or is there another way to list the snapshots by e.g. creation date ?

OS: Ubuntu 20.04
btrfs-progs: 5.4.1-2

root@nc-mcd:~/skripte# btrfs sub list -tcg /
ID      gen     cgen    top level       path
--      ---     ----    ---------       ----
273     1060462 170590  5               snapshots/pre_upgrade_27112020
279     1060464 1006204 5               snapshots/root-19102021


Thanks.

Bernd



--
Bernd Lentes 
System Administrator 
Institute for Metabolism and Cell Death (MCD) 
Building 25 - office 122 
HelmholtzZentrum München 
bernd.lentes@helmholtz-muenchen.de 
phone: +49 89 3187 1241 
fax: +49 89 3187 2294 
http://www.helmholtz-muenchen.de/mcd 


Public key: 

30 82 01 0a 02 82 01 01 00 b3 72 3e ce 2c 0a 6f 58 49 2c 92 23 c7 b9 c1 ff 6c 3a 53 be f7 9e e9 24 b7 49 fa 3c e8 de 28 85 2c d3 ed f7 70 03 3f 4d 82 fc cc 96 4f 18 27 1f df 25 b3 13 00 db 4b 1d ec 7f 1b cf f9 cd e8 5b 1f 11 b3 a7 48 f8 c8 37 ed 41 ff 18 9f d7 83 51 a9 bd 86 c2 32 b3 d6 2d 77 ff 32 83 92 67 9e ae ae 9c 99 ce 42 27 6f bf d8 c2 a1 54 fd 2b 6b 12 65 0e 8a 79 56 be 53 89 70 51 02 6a eb 76 b8 92 25 2d 88 aa 57 08 42 ef 57 fb fe 00 71 8e 90 ef b2 e3 22 f3 34 4f 7b f1 c4 b1 7c 2f 1d 6f bd c8 a6 a1 1f 25 f3 e4 4b 6a 23 d3 d2 fa 27 ae 97 80 a3 f0 5a c4 50 4a 45 e3 45 4d 82 9f 8b 87 90 d0 f9 92 2d a7 d2 67 53 e6 ae 1e 72 3e e9 e0 c9 d3 1c 23 e0 75 78 4a 45 60 94 f8 e3 03 0b 09 85 08 d0 6c f3 ff ce fa 50 25 d9 da 81 7b 2a dc 9e 28 8b 83 04 b4 0a 9f 37 b8 ac 58 f1 38 43 0e 72 af 02 03 01 00 01

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