#!/bin/bash

# Script to "probe" current machine for what linux distribution type it is running on
#
# Output possibilities:
#
#  no args:
#    Unknown
#    el
#    sles
#
#  w/args
#    Unknown
#    el<ver>
#    sles<ver>

# We prefer to use /etc/os-release if it is available
if test -f /etc/os-release; then
  # read in the variables
  . /etc/os-release

  # Map ID to a normalized output
  case ${ID} in

    # RHEL distros
    centos|rhel)
      DISTRO=el
      ;;

    # SLES distros
    sles)
      DISTRO=sles
      ;;

    *)
      DISTRO=unknown
      ;;
  esac

  # get the distro release
  REL=${VERSION_ID}

else
  # If /etc/os-release not found, use lsb_release if it is available
  LSB_RELEASE=`which lsb_release 2>/dev/null`;
  if [ $? -eq 0 ] ; then
    if [ -e ${LSB_RELEASE} ] ; then
      #
      # extract the distro and the distro release
      #
      DISTRO=`lsb_release -i | sed -e "s/Distributor[ \t]*ID:[ \t]*//"`
      REL=`lsb_release -r | sed -e "s/Release:[ \t]*//" -e "s/\..*$//"`

      # Map raw data stream to a normalized output
      case ${DISTRO} in
        CentOS)
          DISTRO=el
          ;;
        RedHatEnterpriseServer)
          DISTRO=el
          ;;
        RHEL)
          DISTRO=el
          ;;
        'SUSE LINUX')
          DISTRO=sles
          ;;
        SLES)
          DISTRO=sles
          ;;
        SUSE)
          DISTRO=sles
          ;;
        Scientific)
          DISTRO=el
          ;;
        *)
          DISTRO=unknown
          ;;
      esac
    fi

  # If lsb_release is not found, look for a /etc/*-release file
  elif test -f /etc/redhat-release; then
    DISTRO=el
    REL=`cat /etc/redhat-release | sed -e "s/^[^0-9]*//" -e "s/[^0-9].*$//"`

  elif test -f /etc/SuSE-release; then
    DISTRO=sles
    REL=`grep SUSE /etc/SuSE-release | sed -e "s/^[^0-9]*//" -e "s/[^0-9].*$//"`
  elif test -f /etc/lsb-release; then
    DISTRO=`grep DISTRIB_ID /etc/lsb-release | sed "s/^DISTRIB_ID=//"`
    REL=`grep DISTRIB_RELEASE /etc/lsb-release | sed -e "s/^DISTRIB_RELEASE=//" -e "s/[^0-9].*$//"`

  # Otherwise it is unknown
  else
    DISTRO=unknown
  fi
fi

#
# If an arg was given, then map to a common distro type and append the release
#
if [ -n "$1" ] ; then
  echo ${DISTRO}${REL}
else
  echo $DISTRO
fi