sha1Me

require 'digest'

mySha1 = Digest::SHA1.new

if (ARGV.index('-h')) && (ARGV[ARGV.index('-h')+1] != nil) # check if '-h' switch is in ARGV[] and the following index is non-null.
    if File.exist?(ARGV[ARGV.index('-h')+1]) #next check if that following index is an existing file.
        File.open(ARGV[ARGV.index('-h')+1]) do|file|
            myBuff = ''
            while not file.eof
                file.read(512, myBuff)
                mySha1.update(myBuff)
            end
        print mySha1
        end
    else
        print 'Invalid file specified'
    end
end