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UNIX for Dummies Questions & Answers
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Post 5919 by rwb1959 on Sunday 26th of August 2001 08:14:42 PM
08-26-2001
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10 More Discussions You Might Find Interesting
1. Programming
I run this code, actually I want to both processes print the message from "data". But only one does. What happens? Anyone can help?
#include <stdio.h>
main(){
int fd, pid;
char x;
fd = open("data",0); /* open file "data" */
pid = fork();
if(pid != 0){
wait(0);
... (2 Replies)
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2. Programming
#include <stdio.h>
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void main(void)
{
pid_t pid;
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char buf;
fork();
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Hello all.
I'm developing a filetransfer application, which is supposed to work sort of like dcc, with multiple transfers etc. Now i wonder what the best way to manage the transfers is. Should i fork() for each new transfer, hogging loads of memory or use pthreads? Maybe I can use select to see... (0 Replies)
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4. Programming
hi all
About this code
for (i = 1; i < n; i++)
if ((childpid = fork()) <= 0)
break;
I really can't understand the output .
and the way fork () return the value .
how about the process Id ,the child process Id and the parent ID
in this case
so please answer me soon (5 Replies)
Discussion started by: iwbasts
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5. Programming
Hi everybody,
I wanna write a code to understand how fork works.
my target
--------------
-Parent creates a file(called temp) and writes into this file "1".Then it closes the file.
-Then parent creates a child and wait until execution of this child ends.
-Then child opens the same... (3 Replies)
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6. UNIX for Advanced & Expert Users
Hi,
I wrote a simple program for understanding the fork command. The code is as below
int main(void)
{
fork(); printf("hi 1 \n");
fork(); printf("hi 2 \n");
fork(); printf("hi 3 \n");
}
I am getting a variation in the number of times the printf is called if i remove the \n from each of... (1 Reply)
Discussion started by: xyz123456
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7. Programming
Hi,
I wrote a simple program for understanding the fork command. The code is as below
int main(void)
{
fork(); printf("hi 1 \n");
fork(); printf("hi 2 \n");
fork(); printf("hi 3 \n");
}
I am getting a variation in the number of times the printf is called if i remove the \n from each... (2 Replies)
Discussion started by: xyz123456
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8. Programming
does fork() spawn only the parent process, what if fork() is looped, does it spawn the parent and the child? (4 Replies)
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9. UNIX for Dummies Questions & Answers
I'm trying to run a simple test on how to use fork(), i'm able to execute the child process first then the parent, but how can I execute parent then child..?
Thanks! (1 Reply)
Discussion started by: l flipboi l
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10. Programming
I understand that fork create a child but I need very simple example that make child useful....
I mean how will make the program faster anyone explain with code plz
using C plz (2 Replies)
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LEARN ABOUT PLAN9
rendezvous
RENDEZVOUS(2) System Calls Manual RENDEZVOUS(2) NAME
rendezvous - user level process synchronization SYNOPSIS
#include <u.h> #include <libc.h> ulong rendezvous(ulong tag, ulong value) DESCRIPTION
The rendezvous system call allows two processes to synchronize and exchange a value. In conjunction with the shared memory system calls (see segattach(2) and fork(2)), it enables parallel programs to control their scheduling. Two processes wishing to synchronize call rendezvous with a common tag, typically an address in memory they share. One process will arrive at the rendezvous first; it suspends execution until a second arrives. When a second process meets the rendezvous the value arguments are exchanged between the processes and returned as the result of the respective rendezvous system calls. Both processes are awakened when the rendezvous succeeds. The tag space is common to processes in the same file name space, so rendezvous only works between processes in the same file name space. If a rendezvous is interrupted the return value is ~0, so that value should not be used in normal communication. SOURCE
/sys/src/libc/9syscall SEE ALSO
segattach(2), fork(2) DIAGNOSTICS
Sets errstr. BUGS
The correlation of rendezvous tags and file name space is a historical accident. If two unrelated processes happen to be in the same name space and do a rendezvous, trouble will result. The solution is to call rfork(RFNAMEG) (see fork(2)) in programs that use rendezvous unless they need to share the name space with their parent. This is especially important in Alef programs. RENDEZVOUS(2)