FJM — Fast JDK Manager

fjm is a fast, lightweight CLI tool to install and manage JDKs and their certificates across multiple shell sessions.

Installation

Download the latest binary for your platform from the GitHub Releases page.

macOS / Linux

curl -Lo fjm https://github.com/your-username/fjm/releases/latest/download/fjm_Linux_x86_64.tar.gz
tar -xzf fjm_Linux_x86_64.tar.gz
chmod +x fjm
mv fjm /usr/local/bin/

Windows

Download the .zip from the releases page, extract it, and add the binary to your PATH.

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Shell Setup

Add the following to your shell profile so fjm can manage your Java environment per session.

bash (~/.bashrc)

eval "$(fjm env)"

zsh (~/.zshrc)

eval "$(fjm env)"

PowerShell ($PROFILE)

fjm env | Invoke-Expression

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Quick Start

# Install a JDK
fjm install 21

# Switch to a specific version
fjm use 21

# Check the current version
java -version

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Commands

fjm install <version>

Downloads and installs the latest JDK for the given major version from Adoptium.

fjm install 21
fjm install 17

fjm use <version>

Switches the active JDK for the current shell session.

fjm use 21

fjm cert add <domain>

Adds a certificate to the active JDK's truststore.

fjm cert add <domain-url> --name <alias>