Print the name of any class in a jar that has a main method:
jar="output/opennlp-tools-1.4.3.jar"
javap -classpath ${jar} $(
jar tf ${jar} \
| grep ass$ \
| cut -f1 -d. \
| tr '[$/]' .
) \
| tr '\n' '@' \
| sed 's,}@,}=,g' \
| tr '=' '\n' \
| grep -w main \
| tr '@' '\n' \
| grep '^public class' \
| awk '{print $3}'
