under X, asks user for a passphrase for ssh-add

 This is Jim Knoble's free implementation of the ssh-askpass program.
 .
 Jim calls this x11-ssh-askpass, but I've decided to call it ssh-askpass to
 make it easier to find, because this is almost certainly the version you
 want. Other ssh-askpass programs are available, some of which may integrate
 better into various desktop environments.