POSTIN

/bin/sh

update-alternatives --install /usr/lib/ssh/ssh-askpass ssh-askpass /usr/bin/ksshaskpass 40
update-alternatives --install /usr/bin/ssh-askpass bssh-askpass /usr/bin/ksshaskpass 40

POSTUN

/bin/sh

[ $1 = 0 ] || exit 0
update-alternatives --remove ssh-askpass /usr/bin/ksshaskpass
update-alternatives --remove bssh-askpass /usr/bin/ksshaskpass

Triggers

ksshaskpass < 0.5

/bin/sh

update-alternatives --remove ssh-askpass /usr/lib/ssh/ksshaskpass
update-alternatives --remove bssh-askpass /usr/lib/ssh/ksshaskpass