http://linux.die.net/man/8/update-alternatives
https://wiki.debian.org/DebianAlternatives

Ubuntu:
http://askubuntu.com/questions/233190/what-exactly-does-update-alternatives-do

CentOS:
http://www.lamolabs.org/blog/5562/5-minute-guide-to-using-the-alternatives-command-on-fedoracentosrhel/

Java stuff:
http://wiki.centos.org/HowTos/JavaDevelopmentKit
http://www.unixmen.com/install-oracle-java-jdk-1-8-centos-6-5/
http://www.unixmen.com/install-apache-ant-maven-tomcat-centos-6-5/

alternatives --install /usr/bin/java java /usr/java/jdk1.8.0_05/jre/bin/java 20000
alternatives --set java /usr/java/jdk1.8.0_05/jre/bin/java

... and the same for javac,jar,javaws


Files (check alternatives):
ls -lA /etc/alternatives/

Samples gcc:
http://askubuntu.com/questions/26498/choose-gcc-and-g-version


man update-alternatives

link groups (master, slaves)


?? altdir, admindir, log

update-alternatives --all --skip-auto
update-alternatives --config <name>

update-alternatives --list <name>


https://github.com/byrongibson/scripts/blob/master/install/scala/typesafe-stack-install.sh

#!/usr/bin/env bash -
# tested on Ubuntu 12.04 only

STACK_TAR="/usr/bin"
STACK_SRC_LOC="/opt/scala/typesafe/stack"
STACK_SRC_VER="2.0.2"
STACK_SRC="$STACK_SRC_LOC/$STACK_SRC_VER/bin"
MAN_SRC="$STACK_SRC_LOC/$STACK_SRC_VER/man"
MAN_TAR="/usr/share/man/man11"
PRIORITY_LEVEL=1200

# install Typesafe Stack alternative for update-alternatives --config scala

update-alternatives --install $STACK_TAR/scala scala $STACK_SRC/scala $PRIORITY_LEVEL \
 --slave $STACK_TAR/fsc fsc $STACK_SRC/fsc \
 --slave $STACK_TAR/g8 g8 $STACK_SRC/g8 \
 --slave $STACK_TAR/giter8.properties giter8.properties $STACK_SRC/giter8.properties \
 --slave $STACK_TAR/jansi.jar jansi.jar $STACK_SRC/jansi.jar \
 --slave $STACK_TAR/sbt sbt $STACK_SRC/sbt \
 --slave $STACK_TAR/sbt-launch.jar sbt-launch.jar $STACK_SRC/sbt-launch.jar \
 --slave $STACK_TAR/sbt-launch-lib.bash sbt-launch-lib.bash $STACK_SRC/sbt-launch-lib.bash \
 --slave $STACK_TAR/scalac scalac $STACK_SRC/scalac \
 --slave $STACK_TAR/scaladoc scaladoc $STACK_SRC/scaladoc \
 --slave $STACK_TAR/scalap scalap $STACK_SRC/scalap \
 --slave $MAN_TAR man.scala $MAN_SRC