JRuby (since 1.6.5) supports a .jrubyrc file in either the current directory or the user's home directory. The format of this file is a series of key/value pairs, with the key being the property name from --properties and the value being the value you'd pass on the command line for the same property.

For more details on JRuby-specific properties and the .jrubyrc file, see JRuby Options.

JRuby allows passing JVM options using the -J<java option> flag, for example -J-Xmx2G to set the max JVM heap to 2GB on OpenJDK. JVM options with spaces should be specified as separate -J flags, as in -J--add-modules -Jmodule/package=readingmodule for the Java 9+ --add-modules flag.

In order to make these flags easier to manage, JRuby 9.2.9 and higher ship with support for .jruby.java_opts files. These files allow you to capture global or application-local JVM options in a single file that is automatically picked up by our launcher.

For more information on passing JVM options using .jruby.java_opts files, see JRuby Java Options Files.