slightly more standard data merge: Symtax.merge (K true) avoids equality on abstract type Pretty.T and gracefully accepts overriding, Symtab.join prefers first entry as usual;
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: invoke Java within the Isabelle environment
CLASSPATH="$(jvmpath "$CLASSPATH")"
exec "${THIS_JAVA:-$ISABELLE_JAVA}" "$@"