reget is not a traditional sftp command, it was added to openssh’s version of sftp a bit ago, but different sftp implementations are different. Technically the correct way to resume a file in the sftp protocol is to seek to position of the file and then read the file. As I recall the spec mandates that at least one forward file seek must be allowed before reading the file, and it is for that purpose. In the erlang ssh_sftp client I’m pretty sure that was set via the position call or something like that (or pread to both set a start position and read from that point on).