Notes.txt

javac *.java
  [ to compile all java files ]

java $classname
  [ to run compile class file ]

jar cf $jarFileName *.class
  [ to create a jar with a $jarFileName and all classes ]

jar cfe $jarFileName $Main-Class *.class
  [ to create jar with an entry-point or Main-Class to be able to run the jar ]

java -jar path/to/jar
  [ to run the jar ] [Note: jar should have Main-Class defined in menifest file to be able to run ]

jar tf path/to/jar
  [ to list jar file content ]

javac -cp path/to/jar1:path/to/jar2 $javaFileName
  [ to compile javaFile by giving CLASSPATH so the javaFile can get other classes from jar files which it doesn't have ]

After above step...
java -cp path/to/jar: class
  [ to run class which needs other classes from the jar file to be able to run ]


let CURRENT_DIR = $PWD
let OTHER_DIR= other_directory

Default CLASSPATH is current directory

If you change CLASSPATH env variable to $OTHER_DIR
## export CLASSPATH=$OTHER_DIR

then you can compile $CURRENT_DIR/javafiles which need classes from other $OTHER_DIR/javafiles
without the need of specifying CLASSPATH (-cp)
## javac $CURRENT_DIR/javafile
because then java command looks for classes in the $OTHER_DIR.

But for running the compiled class file you'll have to again specify CLASSPATH (-cp) to override it
because java will not be able to find your class in $OTHER_DIR.
java -cp $OTHER_DIR: class