Add/remove hosts to/from .ssh/config and etc/hosts files

hostmod

#!/bin/bash

# initialize help variables
usageHelp="Usage: ${0##*/}
  three arguments to add
      usage: hostmod -n hostname -i IPaddress -k keyfile

  one argument to remove
      usage: hostmod -n hostname
"
hostnameHelp="-n memorable name for host"
ipHelp="-i ip address of host"
keyFileHelp="-k name of keyfile in $HOME/.ssh"

# define help functions
printHelpAndExit()
{
  echo "$usageHelp"
  echo "$hostnameHelp"
  echo "$ipHelp"
  echo "$keyFileHelp"
  exit $1
}

printErrorHelpAndExit()
{
        # echo
        # echo "$@"
        # echo
        # echo
        printHelpAndExit 1
}

# initialize argument variables
HOSTNAME=""
IPADDRESS=""
KEYFILE=""

# initialize colors
red='\033[0;31m'
green='\033[0;32m'
NC='\033[0m'

# process arguments
while getopts "hn:i:k:" optionName; do
  case "$optionName" in
    h)  printHelpAndExit 0;;
    n)  HOSTNAME="$OPTARG";;
    i)  IPADDRESS="$OPTARG";;
    k)  KEYFILE="$OPTARG";;
    [?])  printErrorHelpAndExit "$badOptionHelp";;
  esac
done

# execute
if [[ -n $HOSTNAME ]] && [[ -n $IPADDRESS ]] && [[ -n $KEYFILE ]]
    then

      echo -e "Host $HOSTNAME
      User ubuntu
      HostName $IPADDRESS
      IdentityFile $HOME/.ssh/$KEYFILE
  " >> $HOME/.ssh/config

      sudo echo -e "$IPADDRESS\t$HOSTNAME" >> /etc/hosts

      echo -e "${green}Added host in $HOME/.ssh/config${NC}"
      grep -B 1 -A 4 $HOSTNAME $HOME/.ssh/config
      echo -e "${green}Added host in /etc/hosts\n${NC}"
      grep -B 1 -A 1 $HOSTNAME /etc/hosts

elif [[ -n $HOSTNAME ]] && [[ -z $IPADDRESS ]] && [[ -z $KEYFILE ]]

    then

      sed -e "/\<$HOSTNAME\>/,+4d" -i.backup $HOME/.ssh/config
      sudo sed -e "/\<$HOSTNAME\>/d" -i.backup /etc/hosts

      echo -e "${red}Removed host in $HOME/.ssh/config${NC}"
      grep -B 1 -A 4 $HOSTNAME $HOME/.ssh/config
      echo -e "${red}Removed host in /etc/hosts${NC}"
      grep -B 1 -A 1 $HOSTNAME /etc/hosts

else

    printErrorHelpAndExit

fi