Online vs. offline hashes

Someone asked me why the hash of any string produced by Hash'em'all! is different from the hash of the same string produced in bash by

echo "string" | md5sum

The reason is simple: the "echo" command automatically adds a newline at the end of the input string. The "-n" option tells the command not to add it. So

echo -n "string" | md5sum

will give the same result as Hash'em'all!. So simple... But someone was going crazy for this.