Hi all,
Im trying to do a simple program which ask the user for a unix command with the arguments. The program fork and the two process communicate with pipes. The child process call execvp with the command and the father process read the result of the execvp via the pipe.
This program works well with basic commands like ls or echo but when there's interaction between the user and the process for example tr a-z A-Z I think i get a broken pipe on the writing end of my pipe from the parent to the child.
In the parent process, I also have to poll between what the user type and what the child process send but I don't think this is the problem.
here's my code, the name variable and error messages are in french but you get the idea. thank u very much and sorry for bad english.
If you have any questions feel free to ask
---------- Post updated at 12:49 PM ---------- Previous update was at 11:26 AM ----------
I have force a read in the pipe connecting the child process ( the command ) to my parent process and there's nothing so my problem is either 1) the information coming from the user is not arriving at the child or the child is not writing properly in the exit pipe.
Any help would be appreciated... Its my first time with pipes
here's my code, the name variable and error messages are in french but you get the idea.
Not really, I don't. I have no idea what "descripteur" is and why you're writing to it, for example.
It would also help to know what you're trying to do with this command, and what it's actually doing. And maybe minor details like what your operating system is. Because if you're running linux, you could try strace -f ./command parameters to see a trace of system calls as it runs, which will tell you exactly who's waiting for what when.
---------- Post updated at 09:31 PM ---------- Previous update was at 09:03 PM ----------
This isn't right:
Not all text is strings. read() doesn't add a null to the end.
descripteur is descriptor in french its because the parent process is suppose to collect the data from the child and write it in a file specified by descriptor.
I spent all day on this and decide to check the return value fo my dup2 and got an error when redirecting the output of my child process from stdout to the pipe tubeSortie[1].
I try replacing fileno(stdout) with 1 but i keep getting the same error:
Erreur lors du dup stdout Unknown error: 0
Once that's fixed: Your code does actually write to the pipe.
But the read end doesn't see data until the write end is full (or closes). That's probably at least 65536 bytes, if not much more, so you don't see enough by just typing. On EOF you should close the writing pipe and break the loop, which will cause the pipe to send everything it had.
---------- Post updated at 09:52 PM ---------- Previous update was at 09:40 PM ----------
You don't need to do this. STDOUT_FILENO was right in the first place.
Hi!
I'm having problems with pipes... I need comunnications with childs processes and parents, but only one child can comunnicate with parent (first child), others childs can't.
A brief of code:
if(pipe(client1r)<0){
perror("pipe");
}
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270 31|455004|24/03/2010|0001235|72
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