Sponsored Content
Full Discussion: help with fork() command???
Top Forums Shell Programming and Scripting help with fork() command??? Post 302568441 by Corona688 on Thursday 27th of October 2011 10:11:23 AM
Old 10-27-2011
In short, printf() doesn't go directly to the screen -- it waits inside a memory buffer first. When you put a \n on the end, the buffer is flushed. Also, when the program quits, the buffer is flushed.

So, you are putting "welcome to" in the buffer and not printing it to screen before you fork().

The fork()ed process gets a copy of that buffer.

Then you print an \n in both, flushes the buffers in both. Not necessarily in any predictable order, just whenever each happens to be run!

Then they print the rest, quit, and flush again. Again, not necessarily in any predictable order!

If you must printf(), do fflush(stdout) before you fork().
This User Gave Thanks to Corona688 For This Post:
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Fork

What is a fork? Why would one create a fork? What are the advantages and disadvantages of using a fork? Please advise. Thank You. Deepali (5 Replies)
Discussion started by: Deepali
5 Replies

2. Programming

fork() fd

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)
Discussion started by: Herman
2 Replies

3. Programming

fork()

#include <stdio.h> #include <string.h> #include <sys/types.h> #define MAX_COUNT 200 #define BUF_SIZE 100 void main(void) { pid_t pid; int i; char buf; fork(); pid = getpid(); for (i = 1; i <= MAX_COUNT; i++) { sprintf(buf,... (2 Replies)
Discussion started by: MKSRaja
2 Replies

4. Programming

Fork or what?

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)
Discussion started by: crippe
0 Replies

5. Programming

Fork ()

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
5 Replies

6. Programming

fork() help

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)
Discussion started by: alexicopax
3 Replies

7. Programming

Fork()

does fork() spawn only the parent process, what if fork() is looped, does it spawn the parent and the child? (4 Replies)
Discussion started by: Peevish
4 Replies

8. Shell Programming and Scripting

invoke fork command

Hi, I have startup shell script called "xxxxx" for Jboss server which is taking more than expected timeline to complete the process, here I want to use the fork command to start the child process for non dependent component I have a scheduler called "yyyy" which is currently getting invoked... (2 Replies)
Discussion started by: harish76
2 Replies

9. UNIX for Dummies Questions & Answers

fork()

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
1 Replies

10. Programming

Fork!

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)
Discussion started by: fwrlfo
2 Replies
pthread_atfork(3T)														pthread_atfork(3T)

NAME
pthread_atfork() - register fork handlers. SYNOPSIS
PARAMETERS
prepare This function is called before performing the parent This function is called in the parent process after performing the child This function is called in the child process after performing the DESCRIPTION
The function allows an application to install fork handlers. These fork handlers will be called before and after a operation. These han- dlers will be called in the context of the thread calling Similar to the handlers, the application does not need to do anything special for these fork handlers to be called. They will be invoked by the system when a operation occurs. The function is called before the operation in the parent process. The function is called after the operation in the parent process. The function is called after the operation in the child process. If a fork handler is not needed in one or more of these three places, the appropriate fork handler parameter may be set to NULL. A process may install multiple fork handling functions. The and fork handlers will be called in the order in which they were installed (i.e., The fork handlers will be called in the opposite order (i.e., RETURN VALUE
Upon successful completion, returns zero. Otherwise, an error number is returned to indicate the error (the variable is not set). ERRORS
If any of the following occur, the function returns the corresponding error number: [ENOMEM] There is insufficient table space to install the fork handlers. AUTHOR
was derived from the IEEE POSIX P1003.1c standard. SEE ALSO
fork(2), atexit(3). STANDARDS CONFORMANCE
Pthread Library pthread_atfork(3T)
All times are GMT -4. The time now is 02:18 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy