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Kevin D. Clark wrote: > Adam Russell writes: > >>Apparently the difference is that some programs like ssh(maybe yours >>too?) do not read from stdin but, rather, "the terminal". Now, my >>system programming experience is limited so I am not quite sure what >>"reading from the terminal means". Does that mean that it uses >>something like ncurses to read input? If so, how is that different >>than just reading stdin besides just wrapping it in someway? If >>soneoen could care to explain it to me that would be cool. Always >>sort of wondered....... > > This is a FAQ in some places. > > The thing that you are alluding to here is that some programs happily > read from stdin wheras others (most famously the passwd program) go to > the trouble of reading from the controlling terminal (/dev/tty). It's > not really a ncurses thing. > > All of this is done for "security reasons", but I have to confess I > don't understand these anymore since (1) Expect is nearly ubiquitous > nowadays (2) it isn't impossible to write pty code (nefarious or not) > (3) many modern versions of tools like passwd give you the option of > reading from stdin anyways and (4) if you're stupid enough to use such > a feature and leave whatever scripts/etc. that drive this program in > cleartext, then you'll eventually get what you richly deserve. > > The OP didn't mention that his program was reading directly from > /dev/tty, so I doubt that this is relevant to the problem. I'm not > sure what the problem is at this point either. > > Regards, I'm reading from stdin and writing to stdout. Problem is now fixed, after some more googling. I needed an fflush() after my fprintf() calls. I woulda figured stdin and stdout were line buffered if at all, but that turns out not to be the case. > --kevin (changing into his light asbestos underwear right now) Save it for the BBQ.
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