Why not use `tee`? I regularly do `cat ~/.ssh/id_rsa.pub | ssh foo@bar tee -a ~/.ssh/authorized_keys` without repercussion. For larger files I usually use rsyn

Why not use `tee`? I regularly do `cat ~/.ssh/id_rsa.pub | ssh foo@bar tee -a ~/.ssh/authorized_keys` without repercussion. For larger files I usually use rsync as you can resume interrupted transfers