I would like to undelete a large file I deleted using the rm -r command on the directory it was located in. The file was on a 1TB usb external harddisk. Nothing was written to the disk after the file was deleted, I simply unmounted and realised my mistake. I'm fairly sure I know the name of the file, although it would be handy to be able to see a list of previous files in case there was another deleted by mistake.
I've seen this question: How to undelete files on btrfs partition?
I tried what was suggested there but had no luck:
./btrfs-undelete /dev/sdb1 mydir/file.name
Searching roots... found 0 roots.
rm: cannot remove '/tmp/btrfs-undelete.19720': No such file or directory
Didn't find 'mydir/file.name'
I am therefore stumped. Any suggestions would be appriciated.