BTRFS usage- Adding devices, moving data, converting to RAID1, all without rebooting

[oshunluvr]

From the btrfs wiki:

COMMAND SYNTAX

Any command name can be shortened as far as it stays unambiguous, however it is recommended to use full command names in scripts. All command groups have their manual page named btrfs-<group>.
For example: it is possible to run btrfs sub snaps instead of btrfs subvolume snapshot. But btrfs file s is not allowed, because file s may be interpreted both as filesystem show and as filesystem sync.
If the command name is ambiguous, the list of conflicting options is printed.
For an overview of a given command use btrfs command --help or btrfs [command…] --help --full to print all available options.

[Snowhog]

That makes more sense. I simply didn't understand how sudo command su would be valid under any circumstances!