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Java

  • Java binaries are installed at:
  • Compiler: /usr/lib/jvm/default/bin/javac
  • Runtime: /usr/lib/jvm/default/bin/java (or default-runtime)
  • Alternatively you can invoke the symlink /usr/bin/java
pacman -S "jdk11-openjdk" "openjdk11-doc" "openjdk11-src"

Java Archlinux

# Show installed JDKs
archlinux-java status

# Show default JDK
archlinux-java get

# Change default JDK
archlinux-java set "java-17-openjdk" # create symlink /usr/lib/jvm/default -> /usr/lib/jvm/java-17-openjdk

Brew

  • openjdk is keg-only
brew install openjdk
sudo ln -sfn \
  /opt/homebrew/opt/openjdk/libexec/openjdk.jdk \
  /Library/Java/JavaVirtualMachines/openjdk.jdk

Java Debian

# Show java locations
sudo update-java-alternatives -l

## If not, java must be using another jdk, then:
sudo update-alternatives --config java # Java executor
sudo update-alternatives --config javac # Java compiler

Java Home

  • There's no need to set JAVA_HOME if the binaries are already in your $PATH
sudo vim "/etc/environment"
JAVA_HOME="/usr/lib/jvm/default"
JAVA_HOME="/usr/lib/jvm/java-11-amazon-corretto"
JAVA_HOME="/usr/lib/jvm/java-16-openjdk"
source "/etc/environment" # update the current terminal
echo "$JAVA_HOME"

# Or...
export JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:/bin/javac::")

Tomcat

# Download tomcat binary
curl -O "https://ftp.unicamp.br/pub/apache/tomcat/tomcat-10/v10.0.7/bin/apache-tomcat-10.0.7.tar.gz"

# Install to anywhere
sudo mkdir "/opt/tomcat"
sudo tar -zxvf "apache-tomcat-9.0.41.tar.gz"
sudo mv "apache-tomcat-9.0.41/*" "/opt/tomcat"

# Export catalina home to .zshrc
export CATALINA_HOME=/opt/tomcat

# Tomcat permissions (development)
sudo chgrp -R hvitoi "/opt/tomcat"
sudo chown -R hvitoi /opt/tomcat/webapps/ /opt/tomcat/work/ /opt/tomcat/temp/ /opt/tomcat/logs/

# Tomcat permissions (production)
sudo chgrp -R tomcat /opt/tomcat
sudo chown -R tomcat /opt/tomcat/webapps/ /opt/tomcat/work/ /opt/tomcat/temp/ /opt/tomcat/logs/
sudo chmod -R g+r conf
sudo chmod g+x conf
  • Systemd service file ($JAVA_HOME must be set)
  • /etc/systemd/system/tomcat.service
[Unit]
Description=Apache Tomcat Web Application Container
After=network.target

[Service]
Type=forking

Environment=JAVA_HOME=/usr/lib/jvm/java-1.11.0-openjdk-amd64
Environment=CATALINA_PID=/opt/tomcat/temp/tomcat.pid
Environment=CATALINA_HOME=/opt/tomcat
Environment=CATALINA_BASE=/opt/tomcat
Environment='CATALINA_OPTS=-Xms512M -Xmx1024M -server -XX:+UseParallelGC'
Environment='JAVA_OPTS=-Djava.awt.headless=true -Djava.security.egd=file:/dev/./urandom'

ExecStart=/opt/tomcat/bin/startup.sh
ExecStop=/opt/tomcat/bin/shutdown.sh

User=tomcat
Group=tomcat
UMask=0007
RestartSec=10
Restart=always

[Install]
WantedBy=multi-user.target

sudo vim /etc/systemd/system/tomcat.service
sudo systemctl daemon-reload
sudo systemctl start tomcat
sudo systemctl status tomcat
sudo systemctl enable tomcat # OPTIONAL!

# Allow firewall rule for accepting connections from anywhere
sudo ufw allow 8080
  • Add a login to tomcat in order to manage the web app
  • /opt/tomcat/conf/tomcat-users.xml
<tomcat-users>
    <user username="admin" password="123" roles="manager-gui,admin-gui"/>
</tomcat-users>
  • Allow access to Manager and Host Manager apps
  • /opt/tomcat/webapps/manager/META-INF/context.xml
  • /opt/tomcat/webapps/host-manager/META-INF/context.xml
  • Comment out the IP address restriction to allow connections from anywhere
# Restart tomcat service
sudo systemctl restart tomcat

# Access default splash page
open "http://localhost:8080"