will check those. Thanks, Tyler Littlefield. Check out our website: http://tysplace.the-leetest.net check out my blog: livejournal.com/~tylerrl [my programs don't have bugs, just randomly added features] [failure is not an option, it comes bundled with windows!] ----- Original Message ----- From: "Garry Turkington" <garry.turkington@xxxxxxx> To: "Speakup is a screen review system for Linux." <speakup at braille.uwo.ca> Sent: Wednesday, March 29, 2006 2:24 PM Subject: Re: executing code under a child process and another tcp question > > I haven't written multi-threaded code in C for years but here's a few > vague pointers from memory. > > Calling fork() returns an integer, the status of that lets you know > whether or not you're in the parent or child. A common way of working > therefore is something like: > > int id = fork() ; > > if (id == something) > { > /* in child */ > > execl( <path-to-executable>...) ; > /* error check here */ > } > else > /* in parent */ > > So the parent carries on with the main code, the child executes another > executable, script or whatever and that is the child process code. > Obviously the child code can just be embedded in the same source file but > unless its really trivial it becomes unwieldy. > > Pipes are pretty straightforward. Create a pipe, use dup2 to hook up the > parent stdout to the child stdin and vice versa and you have a very crude > but workable way of passing info back and forth. > > So, read up on fork(), execlp(), pipe() and dup2() and you should work it > all out. > > One point though - C is a really unfriendly language to learn things like > multithreaded or socket programming. If you want to learn the concepts > (and with multi-threaded code it will take a very long time) as opposed to > an immediate need to actually use it in C then I'd suggest doing your > learning in another language. The difficulties of the material are great > enough without getting caught around the axle of the particular language > idiosyncracies. > > Regards, > Garry > > -- > Garry Turkington > garry.turkington at gmail.com > > On Mon, 27 Mar 2006, tyler wrote: > >> Hello everyone,, >> Though these questions may bwe boardering on the relm of programming, I >> wasn't really sure where else to ask them, I am aware of the >> blindprogramming list, but don't like to sign up to lists with high >> traffic >> like that one, because sometimes its hard for me to check my email, and >> when >> I get back (just from being on the blindgamers list, and the three lists >> owned by the same organization as the programming at blindprogramming) after >> not reading email for like 4 days, I had over 700 emails. >> Anyway, I have a couple questions, >> I read up on fork, and found that it isn't just something used to eat >> your >> food with, but you can spawn other processes with it. >> But, my main idea was a pipe, I wanted to spawn a child process, and >> create >> a pipe to it, so I read up on pipes to. >> The only thing I have been able to find is how to get my process to >> execute >> shell commands, >> Do I have to stick to shell commands, or can I actually switch execution >> between child and parent. >> Also, how do I get the pid of the parent process? >> Last, I want to start playing with TCP. >> If I send in the raw mode, can I just send a struct as a packet? >> If so, that will only take me reading up on how packetts are formed (I >> know >> the basics) but not the exact ways, and then I can just create a struct >> to >> represent a packet, and send it to where ever I wish. I also as a little >> example wish to create a ping program, and a port scanner, I can do the >> port >> scanner fairly easy I think, with minimal research, but what does the >> ping >> program do? I haven't been able to figure that one out, and I have used >> numerous packett sniffers. >> Things just look garbled. >> Thanks for your help, >> >> >> Tyler Littlefield. >> Check out our website: >> http://tysplace.the-leetest.net >> check out my blog: >> livejournal.com/~tylerrl >> [my programs don't have bugs, just randomly added features] >> [failure is not an option, it comes bundled with windows!] >> >> >> _______________________________________________ >> Speakup mailing list >> Speakup at braille.uwo.ca >> http://speech.braille.uwo.ca/mailman/listinfo/speakup >> > > _______________________________________________ > Speakup mailing list > Speakup at braille.uwo.ca > http://speech.braille.uwo.ca/mailman/listinfo/speakup
