eswitch.sh

#!/usr/bin/env bash

set -euo pipefail

BASE=/etc/hostenvs/

function usage {
  echo "Usage: $0 <environment>"
  echo
  echo "<environment> is the name of a file in ${BASE} to be symlinked to /etc/hosts."
  echo
  echo -n "Available choices: "
  ls ${BASE}
  echo -n "Currently /etc/hosts is "
  if [ -L /etc/hosts ]; then
    echo "a link to $(readlink /etc/hosts)"
  else
    if [ -f /etc/hosts ]; then
      echo "a regular file (not symlinked to anything)"
    else
      echo "something strange ($(file /etc/hosts))"
    fi
  fi
  exit 1
}

if [ "$EUID" -ne 0 ]; then
  echo "Please run $0 as root"
  exit 2
fi

if [ ! -x "${BASE}" ]; then
  echo "Creating ${BASE} for storing environments..."
  mkdir -p "${BASE}"
  mv /etc/hosts "${BASE}"default
  ln -f -s "${BASE}"default /etc/hosts
else
  if [ ! -L /etc/hosts ]; then
    # Non è un link, copiamolo per sicurezza e poi creiamo il link
    mv /etc/hosts /etc/hosts.bak
  fi
fi

if (( $# < 1 )) || [ "$1" == "" ] || [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
  usage
fi

if [ ! -f "${BASE}$1" ]; then
  echo "$1: environment not found"
  usage
fi


ln -f -s "${BASE}$1" /etc/hosts