A bash script for printing out classes in a jar file with version greater than some value

bcversions.sh

#!/bin/bash

JARPATH="$1"
MIN="$2"

if [[ "$JARPATH" == "" ]] || [[ "$MIN" == "" ]]; then
    echo 'This script will scan the classes in a jar file, and print the ones whose '
    echo 'bytecode versions are greater than a given value.'
    echo ''
    echo 'Usage bash bcversions.sh JARPATH MAXVERSION'
    echo ' JARPATH  The path to the jar file to check'
    echo ' MAXVERSION The max classfile version to ignore.'
    echo ''
    echo 'Example: '
    echo 'bash bcversions /path/to/myapp.jar 52'
    echo '  The above will output all classes in myapp.jar with a bytecode version greater than 52'
    echo ''
    echo 'Created by Steve Hannah, Codename One https://www.codenameone.com'
    exit 1
fi

for line in `jar tf $JARPATH`; do 
if [[ ! "$line" == *.class ]]; then
    continue
fi
    line=$(echo "$line" | sed  s/\\//\./ | sed s/\.class//); 
    
    _version=$(javap -cp $JARPATH -verbose "$line" | grep -i "major version" | sed s/[^0-9]*//);
     
    if [[ "$_version" -gt "$MIN" ]]; then
        echo "$line: version $_version"
    fi
    
done