On Tue, 8 Oct 2024 15:28:17 GMT, Jan Lahoda <jlah...@openjdk.org> wrote:
> Currently, running `java` without any parameters will lead to an output that > is a full `--help`, which is over 100 lines (on my computer at least), and it > feels overwhelming. And many people might actually want to run JShell/REPL, > not the `java` executable, but it is difficult find out about JShell. > > The proposal herein is to print a much shorter help, together with a pointer > to JShell, when the executable does not know what to do. I.e. there is > nothing specified to start, and no option like `--help` is specified. In > particular, on my machine, it prints: > > Usage: java [java options...] <application> [application arguments...] > > Where <application> is one of: > <mainclass> to execute the main method of a compiled main > class > -jar <jarfile>.jar to execute the main class of a JAR archive > -m <module>[/<mainclass>] to execute the main class of a module > <sourcefile>.java to compile and execute a source-file program > > Where key java options include: > --class-path <class path> > where <class path> is a list of directories and JAR archives to search > for class files, separated by ":" > --module-path <module path> > where <module path> is a list of directories and JAR archives to search > for modules, separated by ":" > -version > to print product version to the error stream and exit > > For additional help on usage: java --help > For an interactive Java environment: jshell > > > The full `java -help` with these changes is as follows: > > Usage: java [options] <mainclass> [args...] > (to execute a class) > or java [options] -jar <jarfile>.jar [args...] > (to execute a jar file) > or java [options] -m <module>[/<mainclass>] [args...] > java [options] --module <module>[/<mainclass>] [args...] > (to execute the main class in a module) > or java [options] <sourcefile>.java [args] > (to execute a source-file program) > > Arguments following the main class, source file, -jar <jarfile>.jar, > -m or --module <module>/<mainclass> are passed as the arguments to > main class. > > where options include: > > -cp <class search path of directories and zip/jar files> > -classpath <class search path of directories and zip/jar files> > --class-path <class search path of directories and zip/jar files> > A ":"-separated list of directories, JAR archives, > and ZIP archives to search for class files. > -p <module path> > --module-path <module path>... > ... This pull request has now been integrated. Changeset: c7be41ee Author: Jan Lahoda <jlah...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/c7be41ee0cf632c0d24f4444afefe2f7ff02f23a Stats: 106 lines in 3 files changed: 45 ins; 2 del; 59 mod 8340133: Add concise usage message to the java executable Reviewed-by: jpai, alanb, ihse, rriggs ------------- PR: https://git.openjdk.org/jdk/pull/21411
