issue with screenshot:
https://github.com/aeshell/mterm/issues/24

weird because cat doing well, but client program doing well too:

cat:
catch(FileNotFoundException fnfe) {
commandInvocation.getShell().err().println("cat: "+fnfe.getMessage());
return CommandResult.FAILURE;
}

client program:
getPos().write((command).getBytes()); < ----
getPos().write(Config.getLineSeparator().getBytes());
getPos().flush();