xxx@zzz:~/Downloads$ sudo ./install-java.sh -f jdk-15.0.2_linux-x64_bin.tar.gz 
[sudo] password for expert: 
Installing: jdk-15.0.2_linux-x64_bin.tar.gz
Extracting jdk-15.0.2_linux-x64_bin.tar.gz to /usr/lib/jvm
JDK is extracted to /usr/lib/jvm/jdk-15.0.2
Run update-alternatives commands? [y/N] y
Running update-alternatives...
update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-15.0.2/bin/java 10000 --slave /usr/bin/jaotc jaotc /usr/lib/jvm/jdk-15.0.2/bin/jaotc --slave /usr/bin/jar jar /usr/lib/jvm/jdk-15.0.2/bin/jar --slave /usr/bin/jarsigner jarsigner /usr/lib/jvm/jdk-15.0.2/bin/jarsigner --slave /usr/bin/javac javac /usr/lib/jvm/jdk-15.0.2/bin/javac --slave /usr/bin/javadoc javadoc /usr/lib/jvm/jdk-15.0.2/bin/javadoc --slave /usr/bin/javap javap /usr/lib/jvm/jdk-15.0.2/bin/javap --slave /usr/bin/jcmd jcmd /usr/lib/jvm/jdk-15.0.2/bin/jcmd --slave /usr/bin/jconsole jconsole /usr/lib/jvm/jdk-15.0.2/bin/jconsole --slave /usr/bin/jdb jdb /usr/lib/jvm/jdk-15.0.2/bin/jdb --slave /usr/bin/jdeprscan jdeprscan /usr/lib/jvm/jdk-15.0.2/bin/jdeprscan --slave /usr/bin/jdeps jdeps /usr/lib/jvm/jdk-15.0.2/bin/jdeps --slave /usr/bin/jfr jfr /usr/lib/jvm/jdk-15.0.2/bin/jfr --slave /usr/bin/jhsdb jhsdb /usr/lib/jvm/jdk-15.0.2/bin/jhsdb --slave /usr/bin/jimage jimage /usr/lib/jvm/jdk-15.0.2/bin/jimage --slave /usr/bin/jinfo jinfo /usr/lib/jvm/jdk-15.0.2/bin/jinfo --slave /usr/bin/jlink jlink /usr/lib/jvm/jdk-15.0.2/bin/jlink --slave /usr/bin/jmap jmap /usr/lib/jvm/jdk-15.0.2/bin/jmap --slave /usr/bin/jmod jmod /usr/lib/jvm/jdk-15.0.2/bin/jmod --slave /usr/bin/jpackage jpackage /usr/lib/jvm/jdk-15.0.2/bin/jpackage --slave /usr/bin/jps jps /usr/lib/jvm/jdk-15.0.2/bin/jps --slave /usr/bin/jrunscript jrunscript /usr/lib/jvm/jdk-15.0.2/bin/jrunscript --slave /usr/bin/jshell jshell /usr/lib/jvm/jdk-15.0.2/bin/jshell --slave /usr/bin/jstack jstack /usr/lib/jvm/jdk-15.0.2/bin/jstack --slave /usr/bin/jstat jstat /usr/lib/jvm/jdk-15.0.2/bin/jstat --slave /usr/bin/jstatd jstatd /usr/lib/jvm/jdk-15.0.2/bin/jstatd --slave /usr/bin/keytool keytool /usr/lib/jvm/jdk-15.0.2/bin/keytool --slave /usr/bin/rmid rmid /usr/lib/jvm/jdk-15.0.2/bin/rmid --slave /usr/bin/rmiregistry rmiregistry /usr/lib/jvm/jdk-15.0.2/bin/rmiregistry --slave /usr/bin/serialver serialver /usr/lib/jvm/jdk-15.0.2/bin/serialver
update-alternatives: error: alternative jaotc can't be slave of java: it is a master alternative
update-alternatives: error: alternative /usr/lib/jvm/jdk-15.0.2/bin/java for java not registered; not setting
Do you want to set JAVA_HOME environment variable in /home/expert/.bashrc? [y/N] y