So, I know that one can use the system(); command in C to run an external command. My question is, is there any way to interact with that program from within your C code?

I'm trying to piece together an extremely lightweight but relatively full-featured set of apps for an ancient machine, and I'd love a media player with a nicer playlist-type interface similar to rhythmbox, but in gtk+2 only and very memory concious. I'm trying to write it myself and I'm wondering if there's anyway to leverage MPlayer's existing interactive console controls or if I'll have to delve into the MPlayer (or perhaps MPlayerXP) code.

You can open a pipe to the program, and send data to it that way (the program reading it from stdin). This is suitable for programs which read commands from stdin, e.g. bc.

Got it, I suppose my inexperience at programming is showing, as I have no clue how to open a pipe, but I suppose now is a good time to rtfm! It's good for me :-)

Thanks!

It's really easy:

man 2 pipe
man 1 mkfifo

popen is probably the call you want to read up on. popen will start a process and depending on the type you select, you can read from the pipe, or write to it. Note that you cannot do both reading and writing. If you need to both write to and read from a process, you can do it using pty. Here's some example code snippets: http://www.codase.com/search/call?name=openpty

It would appear that pty's are exactly what I'm looking for, but I'm a bit unsure of the manpage for openpty(). It makes constant reference to int values master and slave? The way I'm understanding it, I give it master, and a pointer to slave, and it changes the contents of slave. But then how do I go from having master and slave to having read/write access to a stream?

by "file descriptor" do they mean that amaster is an integer representation of a null-terminaled string containing the filesystem location, like /dev/ptyp2 for example?

I'm having a remarkably hard time finding any documentation on openpty() or forkpty(). The little documentation I have found, just the man page, is what leads me to believe that I want forkpty(), but can anyone point me to some more documentation? I can't figure out how to use these. Thanks!

You can do a lot of stuff, my favourite is still attaching a library
like paco on sourceforge does - but actually, I dont think its
using system()

if openpty() and/or forkpty() isn't well documented, is there any other way? I do need two way communication.