On Sat, Aug 22, 2009 at 5:30 PM, Chet Ramey <chet.ra...@case.edu> wrote: > > Bob Proulx wrote: > > nico raffo wrote: > >> I'm writing a simple terminal emulator (on linux using standard pty > >> libraries) and have run across some behavior in bash that I cannot > >> explain after several weeks of reading documentation. > > > > I am not sure of the exact cause of your trouble. But having been a > > few days and no one else suggesting anything I thought I would jump in > > anyway. > > > > Hopefully you will be using a free license on your code? And then you > > could post it and perhaps someone might see something in it then. > > > >> However with bash, the shell doesn't respond at all until a > >> <CR> is sent, and then bash only sends the output of the command, not > >> the command itself. If my terminal emulator is expecting the shell to > >> provide all display text, it wouldn't show the commands at all. > > > > This seems like you are tripping into the difference between different > > tty driver settings of raw mode and canonical input mode (aka cooked > > mode). > > I think it's how the terminal emulator sets the ECHO flag in the > termios local status word (c_lflag & ECHO). If that bit is set, > readline echoes the text it reads back to the terminal. If it's > not, readline assumes that the terminal is in no-echo mode and that > it should not echo the characters. > > I assume that the difference between bash and zsh is that zsh sets > the ECHO bit and leaves it set when it exits. A subsequent invocation > of bash picks up that flag and echoes input as a result. > > Chet
Thanks for pointing me in the right direction. The ECHO flag did the trick. Nico
