reset known_hosts entry for a hostname

kh-reset.sh

#! /usr/bin/env zsh

if [[ $# != 1 ]]; then
  print Usage: kh-reset hostname
  exit 1
fi

# Expand the different hostnames and IP
if [ -x /usr/bin/dscl ]; then
  # macOS
  hosts="$hosts $(dscl . read /Hosts/$1 | awk '/^IPAddress/ { print $2 }')"
else
  # sanity
  hosts="$1 $(getent hosts $1)"
fi

# Remove all matching entries from known_hosts
for h in ${=hosts}; do ssh-keygen -R $h >& /dev/null; done

# Grab the new key into known_hosts
ssh-keyscan -tdsa,rsa ${=hosts} >> $HOME/.ssh/known_hosts 2>/dev/null