jvm

jvm installs, manages and runs different JDKs on a user's system. It finds compatible JDK builds, downloads and verifies them, keeps them in user storage and lets you pick which one to use, either persistently or per command.

default set <selector>, home, env and exec automatically install a JDK when no installed JDK matches the selector. Existing local matches work offline.

The scripts are small, have no dependencies and are meant to be copied into your Java projects. jvm (Bash), jvm.ps1 (native Windows PowerShell 5.1) and jvm.cmd (Windows launcher) need no Java, no package manager and no runtime installation step. That gives you a sure-fire way for your users to build and run your project, even when they don't have Java installed.

On Linux and macOS, the Bash script supports Bash 3.2 and later. On Windows, use current Git Bash, MSYS2 or Cygwin, or Windows PowerShell 5.1.

Using it in your projects

Copy the three scripts jvm, jvm.cmd and jvm.ps1 to the root of your project, and tell your users they can run your application by simply typing:

./jvm x 25+ your_app

This runs your_app with a matching JDK (Java 25 or newer), downloading and installing Temurin if no installed JDK matches. Use .\jvm.cmd on Windows outside Bash.

Or you can configure your PATH and JAVA_HOME for the duration of your shell session by running:

eval $(./jvm env 25+)

(You can run plain ./jvm env if you need a reminder on how to use it with eval)

To avoid repeating the JDK version in every command, add a .jvmrc file to the project root (see Configuration):

java=25+

At which point the previous command can be simplified to:

eval $(./jvm env)

Neat Trick (Runnable .java files)

Take a look at the hello.java file, it has this strange line at the top of the file which, on Linux and Mac, tells your shell how to run the code.

///usr/bin/env ./jvm x 25+ java "$0" "$@" ; exit $?
void main() {
    IO.println("Hello, World!");
}

And then you simply run it like:

./hello.java

(PS: don't forget to make the file executable first with chmod +x hello.java)

Now, you could already do this without jvm, but the nice thing is that now it will even work for people who don't have Java installed. And it will even make sure it's the correct version!

Using it installed

Copy the scripts to a directory on your PATH, for example ~/.local/bin:

mkdir -p ~/.local/bin
cp jvm jvm.cmd jvm.ps1 ~/.local/bin/
chmod +x ~/.local/bin/jvm

On Windows you will probably need to add that directory (for example %USERPROFILE%\.local\bin) to your PATH yourself.

To make the default JDK available in every shell, add this once to your shell profile:

# Unix
export JAVA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}/jvm/jdks/default"
export PATH="$JAVA_HOME/bin:$PATH"

# Git Bash / Cygwin / MSYS2
export JAVA_HOME="$(cygpath -m "${XDG_DATA_HOME:-$HOME/.local/share}/jvm/jdks/default")"
export PATH="$(cygpath -u "${JAVA_HOME}")/bin:$PATH"

Usage

jvm <command> [options] [selector]

Command	Purpose
available, a [-t] [selector]	Show compatible JDKs available to download
install, i [-d] [-v] [selector]	Download, verify and install a JDK (-d selects the global default; -v selects its major default)
uninstall, u <selector>	Remove an installed JDK
list, l [selector]	Show installed JDKs, even offline
default [<major>], d [<major>]	Query the global or per-major default offline
default set [<major>] <selector>, d set [<major>] <selector>	Set the global or per-major default, installing if needed
home, h [selector]	Print the selected JDK home, installing if needed
env, e [-f] [selector]	Print shell exports for the selected JDK, installing if needed
exec, x <selector> [--] <command> [args...]	Run a command with the selected JDK, installing if needed

exec and x require a selector. Use _ to resolve project java, then user java, then the global default, then Java 25. Configuration errors, failed configured selections and unusable defaults are errors. The _ placeholder is exclusive to exec; it is not a configuration value. Other commands give it no placeholder meaning and retain their existing exact-directory ID rules. home and env use the same precedence when their selector is omitted. jvm default queries the global default; jvm default 21 queries Java 21. After set, one argument is a selector (jvm default set 21 sets the global default using selector 21); two arguments are a scope major and selector (jvm default set 21 temurin-21 sets the Java 21 default). A scope is a positive integer without leading zeros, and the selected JDK must match that major. Queries never install. The d alias uses the same grammar.

One optional -- immediately after the exec selector is skipped. The command must be nonempty; it and every later argument are forwarded unchanged.

Selectors are a major (21), a distro (temurin, for available/list), a distro-major (temurin-21) or a full installed ID. Ranges such as 21+, 21..26 and temurin-21+ are also accepted, except for uninstall.

Examples:

jvm available temurin              # what can be installed
jvm install                        # install the default JDK (Temurin 25)
jvm i -d temurin-21                # install Temurin 21 and make it the default
jvm i -v temurin-25                # install Temurin 25 and select its major default
jvm i -d -v temurin-25             # select both defaults (major first, then global)
jvm list                           # what is installed
jvm default set 21 temurin-21      # set the default for Java 21
jvm home 21                        # print JDK 21's home, installing if needed
eval "$(jvm env temurin-21)"       # use Temurin 21 in the current shell
jvm x 21..26 java -version         # run with the highest matching JDK
jvm x _ java -version              # use configuration/default selection
jvm uninstall temurin-21

Configuration

Optional key=value lines, read from ./.jvmrc and then $XDG_CONFIG_HOME/jvm/config (or ~/.config/jvm/config):

• java=21+ selects the Java major or range.
• distro=graalvm-community selects the distribution.

A command-line selector overrides the project file, which overrides the user file. Configuration does not affect default, available, list, uninstall or help. Run jvm --help for the full reference, and see SPEC.md for the detailed behavior.