should put pig*.jar into CLASSPATH during run pig command?

[lulynn_2008]

 Hello,
In pig script of pig-0.8.1, I did not find command line for adding pig*.jar 
into CLASSPATH environment variable. Just the following:
# during development pig jar might be in build
for f in $PIG_HOME/build/pig-*-SNAPSHOT.jar; do
    CLASSPATH=${CLASSPATH}:$f;
done

Should I add some commands in pig script for adding pig*.jar into CLASSPATH? If 
no need, please tell your opinion. Thank you.