print or match Host and Hostname aliases from ~/.ssh/config

sshaliases

#!/bin/bash

function usage() {
    echo "usage:"
    name=`basename $0`
    echo "$name: print Host and Hostname aliases from ~/.ssh/config"
    echo "$name foo: grep for foo in above output"
    echo "$name -e|--exact foo: grep for '^foo ' in above output and print only hostname.  example: ping \$(sshaliases --exact foo)"
    echo "$name -h|--help: this help"
}
 
EXACT=""
MATCH=()

for i in "$@"
do
case $i in
    -e|--exact)
        EXACT="YES"
        shift
    ;;
    -h|--help)
        usage
        exit
    ;;
    *)
        MATCH+=("$1") # save it in an array for later
        shift
    ;;
esac
done

function maybe_cut() {
  if [ "$EXACT" == "YES" ] ; then
      cut -d' ' -f2
  else
      cat
  fi
}

function maybe_grep() {
  if [ "$MATCH" == "" ] ; then
      cat
  elif [ "$EXACT" == "YES" ] ; then
      grep "^${MATCH} "
  else
      grep "${MATCH}"
  fi
}

awk '
/^Host / {
   gsub("^Host ", "", $0);
   printf "%s ", $0;
}
/^[ \t]+Hostname / {
   gsub("^[ \t]*Hostname[ \t]+", "", $0);
   print;
}

' < ~/.ssh/config | sort | maybe_grep | maybe_cut