regenerate missing public key

2011-05-11 17:57:21 -0700 I've had to do this a surprising number of times lately, and have had to figure it out anew each time. So here it is—for my future reference—how to regenerate from your private key the missing corresponding public key in such a way that it is usable in the ~/.ssh/authorized_keys file:
ssh-keygen -i -f <( ssh-keygen -e -f id_rsa ) >