Sponsored Content
Full Discussion: hello friends
Top Forums UNIX for Advanced & Expert Users hello friends Post 302213777 by newson on Friday 11th of July 2008 02:52:50 AM
Old 07-11-2008
Quote:
Originally Posted by flyingpenguin
Okay, visit:

Beej's Guide to Unix IPC

This is a comprehensive guide to interprocess communication.


Today's lesson is on piping. You have process A, and process B, created by using the fork() command. You want the output of process A to be the input to process B. This is called piping. The following code excerpt demonstrates Inter Process Communication between two child processes, Process A, and Process B. Process A and Process B are running shell commands.


Code:
	int pipeID[2]; /* Pipes Have two values, one for the process A */
                                /* And one for process B. Think of each value */
                                /* as an end to the pipe */
/* pipeid[0] is process A, pipeid[1] is process B */
	pipe(pipeID); /* Create Pipe. */
	
    /* Fork current process to create process A and process B. */
/*Both child processes. Process A is created by the first fork(), */
/*process B by the second fork().  */

// Process A code
	if (fork()==0){ /* If the new process A is a child */
	    // child
		close(pipeID[0]);         //write stdout
		dup2(pipeID[1],1);       // to pipe using dup
		fillArgs(sPipe[0],&args); /* Create agrc and argv */
		execvp(args.argv[0],args.argv); // Execute
		close(pipeID[1]);// stdout goes to pipe.
	}
// Process B code
	if (fork()==0){ /* If the new process is a child */
		close(pipeID[1]);		//read from pipe 1 stdout
		dup2(pipeID[0],0);		//as stdin.
		fillArgs(sPipe[1],&args2);   /* Create argc and argv */
		execvp(args2.argv[0],args2.argv); // Execute 
		close(pipeID[0]);// process B reads stdin from pipe
	}
	close(pipeID[1]); /* Close pipes else, we don't want to have stdin, and stdout */	
	close(pipeID[0]); /* permanently redirected. */

I know my example isn't easy. At least I gave it a try Smilie
thanks for reply....
 

5 More Discussions You Might Find Interesting

1. IP Networking

hi friends

i have been in trouble please help me out i have developed a message queue.it is a simple message queue program after running it give error like NO SPACE LEFT ON DEVICE what is this error how could i solve this problem i am working on solaris9.2 (2 Replies)
Discussion started by: ramneek
2 Replies

2. Shell Programming and Scripting

hi friends....

hi friend i am facing problem in taking input from a file to the variable .. read fname if then cd $fname pwd ls > new_temp1 cat new_temp1 fi terminal=`tty` exec < $new_temp1 while read line do echo $line done exec < $terminal (2 Replies)
Discussion started by: newson
2 Replies

3. Shell Programming and Scripting

hi friends..........

hello friends ........ i want to visit the directory recusvely through and shell script . and want to get the output of " stat " command for each file .i tried by this way but unable to visit the each file . #!/bin/bash echo "enter the file name" read file fun() ... (3 Replies)
Discussion started by: newson
3 Replies

4. What is on Your Mind?

Time to have FUN my Unix/Linux friends...(One liners)...MUST read.. !!

As a mind refresher, I was thinking to start a new thread for ONE LINERS....funny/weird or any technical one liners.... Let me start first...... ================================= #!/bin/ssh #The Unix Guru's View of Sex unzip ; strip ; touch ; grep ; finger ; mount ; fsck ; more ; yes ;... (3 Replies)
Discussion started by: Rahulpict
3 Replies

5. What is on Your Mind?

You Want to Spend Time with Friends and Family a UNIX.com Cartoon Explainer

Well, this was kinda fun and different: You Want to Spend Time with Friends and Family a UNIX.com Cartoon Explainer https://youtu.be/6jPDpuxI2OA You want to spend time with friends and family. But you are stuck on some problem... Your Linux or Unix code is buggy and you don't know... (1 Reply)
Discussion started by: Neo
1 Replies
curl_getenv(3)							  libcurl Manual						    curl_getenv(3)

NAME
curl_getenv - return value for environment name SYNOPSIS
#include <curl/curl.h> char *curl_getenv(const char *name); DESCRIPTION
curl_getenv() is a portable wrapper for the getenv() function, meant to emulate its behaviour and provide an identical interface for all operating systems libcurl builds on (including win32). AVAILABILITY
This function will be removed from the public libcurl API in a near future. It will instead be made "available" by source code access only, and then as curlx_getenv(). RETURN VALUE
If successful, curl_getenv() returns a pointer to the value of the specified environment. The memory it refers to is malloc()ed so the application must free() this when the data is no longer needed. When curl_getenv(3) fails to find the specified name, it returns a null pointer. NOTE
Under unix operating systems, there isn't any point in returning an allocated memory, although other systems won't work properly if this isn't done. The unix implementation thus has to suffer slightly from the drawbacks of other systems. SEE ALSO
getenv(3C), libcurl 7.12 30 April 2004 curl_getenv(3)
All times are GMT -4. The time now is 05:56 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy