Handy shellscript

Find jar compile version

$ for thing in *jar;do echo $thing;dir=`echo $thing | sed "s/.jar$//"`;mkdir -p $dir;(cd $dir;jar xf ../$thing;class=`find . -name "*.class" | head -1`;javap -v $class 2>/dev/null| grep major);rm -rf $dir 2>/dev/null;done | tee versions.txt