avoid jdk-11.0.6+10: it shows problem "S8217731: Font rendering and glyph spacing changed from jdk-8 to jdk-11" https://bugs.openjdk.java.net/browse/JDK-8217731 even though the changelog claims to have resolved this;
# -*- shell-script -*- :mode=shellscript:
#
# determine general hardware and operating system type for Isabelle system tools
#
ISABELLE_PLATFORM_FAMILY=""
ISABELLE_PLATFORM32=""
ISABELLE_PLATFORM64=""
ISABELLE_WINDOWS_PLATFORM32=""
ISABELLE_WINDOWS_PLATFORM64=""
case $(uname -s) in
Linux)
ISABELLE_PLATFORM_FAMILY="linux"
ISABELLE_PLATFORM32=x86-linux
ISABELLE_PLATFORM64=x86_64-linux
;;
Darwin)
ISABELLE_PLATFORM_FAMILY="macos"
case $(sw_vers -productVersion) in
10.10*|10.11*|10.12*|10.13*|10.14*)
ISABELLE_PLATFORM32=x86-darwin
ISABELLE_PLATFORM64=x86_64-darwin
;;
*)
ISABELLE_PLATFORM64=x86_64-darwin
;;
esac
;;
CYGWIN_NT*)
ISABELLE_PLATFORM_FAMILY="windows"
ISABELLE_WINDOWS_PLATFORM32="x86-windows"
ISABELLE_WINDOWS_PLATFORM64="x86_64-windows"
case $(uname -m) in
x86_64)
ISABELLE_PLATFORM64=x86_64-cygwin
;;
i?86)
ISABELLE_PLATFORM32=x86-cygwin
;;
esac
;;
esac