On Tuesday, December 9, 2014, Ken Thomases <k...@codeweavers.com> wrote:
> On Dec 9, 2014, at 8:24 AM, SevenBits <sevenbitst...@gmail.com > <javascript:;>> wrote: > > > Do you know how to trigger the automatic flushing of standard output > like you described? There doesn't seem to be anything in NSTask to do it, > though it probably wouldn't be there anyway. Is it perhaps a C function > call? I do apologize for asking a basic question, but the Internet is full > of people wanting to get the results of a BSD-layer command, and not > through communicating with the process via a Terminal-like interface, and > my Google-fu is not up to the task. > > The only way to make it automatic is to have the standard input connected > to a terminal device. For communication between two processes, you would > use a pseudo-terminal device: > > > https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man4/pty.4.html > > https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/openpty.3.html > > I actually just figured this out, but those are great; I'll certainly take a look at them. I haven't done really low-level C stuff like that for some time, which is why I couldn't remember the functions. > However, that brings with it the requirement that you emulate a terminal. > The subprocess will be able to detect that it's connected to a terminal and > may attempt to do terminal-like things, which the parent process would have > to expect and respond to. That's a complicated mess. I control the source code to the tool that is being called, and I have modified it to make sure that no such calls are being made. This is a very simple console application; if it needed ncurses or something of that sort I'd be panicking right now. > > If you are building the command-line tool from source, then I recommend > that you have it use setvbuf() to set standard output to line buffered. > And, any place where it tries to read from standard input, call fflush() to > flush standard output first. Okay, thanks for the advice. I have noticed one small issue: my app receives from the process and prints back all of the app's input. That, and the app's outputs are buffered, so in some cases it takes a while for its output to reach my "terminal", making it appear to be hanging, but that's a minor issue. > > Regards, > Ken Thanks a lot everyone' -- SevenBits _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
