javac : command not found

Worked for me with this command:

yum install java-devel

Use the following sudo command:

sudo yum install java-1.6.0-openjdk-devel

You installed the Java Runtime Environment (JRE) only, which does not provide javac. For javac, you have to install the OpenJDK Development Environment. You can install java-devel or java-11-devel, which both include javac.

By the way: you can find out which package provides javac with a yum search, e.g.

su -c 'yum provides javac'

on more recent releases of CentOS e.g. 6 the command changes to

su -c 'yum provides */javac'