PostgreSQL 12 -> 13 upgrade check script

check_postgresql_12.sh

#!/bin/bash

function -h {
  cat <<USAGE
   USAGE: Check postgresql database for pg_pltemplate modifcations. Sanity checks before upgrading 12 -> 13

   -p / --port     PostgreSQL port
   -v / --verbose  debugging output

      ./${0##*/}
USAGE
}; function --help { -h ;}

function msg { out "$*" >&1 ;}
function out { printf '%s\n' "$*" ;}
function err { local x=$? ; msg "$*" ; return $(( $x == 0 ? 1 : $x )) ;}

function main {
  local verbose=false
  local port=5432
  while [[ $# -gt 0 ]]
  do
    case "$1" in                                      # Munging globals, beware
      -p|--port)            port="$2"; shift 2 ;;
      -v|--verbose)         verbose=true; shift 1 ;;
      *)                    err 'Argument error. Please see help: -h' ;;
    esac
  done
  local error_found=false
  if [[ $verbose == true ]]; then
    set -ex
  fi

  for db in $(psql -tc "SELECT datname FROM pg_database;")
  do
    if [[ "${db}" != "template0" ]]; then      
      msg "Checking database ${db}"
      local dump=$(pg_dump --port ${port} --schema-only --quote-all-identifiers ${db} | grep pg_pltemplate)
      if [ ! -z "$dump" ]; then
          msg "${dump}"
          err "ERROR: ${db} contains pg_pltemplate modifications. pg_upgrade will fail"
          msg "HINT: Revert REVOKE ... FROM ... statements using GRANT ... TO ... (and viceversa)" 
          error_found=true
      fi
    fi
  done

  if [ ${error_found} = "true" ]; then
    msg "CRITICAL: upgrade to postgresql 13 will fail"
    exit 1
  else
    msg "OK: no pg_pltemplate modifications were found"
    exit 0
  fi
}

if [[ ${1:-} ]] && declare -F | cut -d' ' -f3 | fgrep -qx -- "${1:-}"
then
  case "$1" in
    -h|--help) : ;;
    *) ;;
  esac
  "$@"
else
  main "$@"
fi