more uniform status -- accommodate spurious Exn.Interrupt from user code, allow ML_Compiler.exn_messages_id to crash;
tuned signature;
#!/usr/bin/env bash
#
# Author: Markus Wenzel, TU Muenchen
#
# DESCRIPTION: run a program in a modified environment
## diagnostics
PRG="$(basename "$0")"
function usage()
{
  echo
  echo "Usage: isabelle $PRG [CMDLINE ...]"
  echo
  echo
  echo "  Run CMDLINE within the Isabelle environment (via the system's env command)."
  echo
  exit 1
}
## main
[ "$1" = "-?" ] && usage
exec /usr/bin/env "$@"