Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: fork(), could you explain!!
Top Forums Programming fork(), could you explain!! Post 302569181 by gabam on Sunday 30th of October 2011 12:35:30 AM
Old 10-30-2011
fork(), could you explain!!
Dear friends,
We are learning UNIX system programming as part of our course. I came across this simple program, which the teacher didn't explain well enough. could you please explain this program fully

Code:
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
int main()
{
int pid;
int status = 0;
if(pid = fork())
{
pid = wait(&status);
printf("%d\n",pid);
}
else
{
exit(status);
}
return 0;
}

And why does this program give an output of 912???
Thanks
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

can anyone explain this?

:start /@~/{ h s/\(.*\)@~.*$/\1/ s/@~$// s/@~/\ /g p g s/.*@~\(.*\)/\1/ } //{ N s/\n/ / b start } (2 Replies)
Discussion started by: djkane
2 Replies

2. UNIX for Dummies Questions & Answers

oh fork() and vfork() someone explain the difference?

Can somebody explain to me the differences between fork() and vfork() system calls using C programs which I can implement in the UNIX environement? (1 Reply)
Discussion started by: lvkchaitanya
1 Replies

3. Shell Programming and Scripting

Please can any one explain this ${0##/}

I did not understand what is ${0##/} PGM=${0##/} TMP=/tmp/${PGM}.$$ Please explain me. (2 Replies)
Discussion started by: gadege
2 Replies

4. Shell Programming and Scripting

please explain the below

could u please convert the below statement to shell script ---------- logdir=/smp/dyn/logfiles/cpm/pgm/pgIm $logdir = $logdir ."/pgIm${toDate}*"; ---- could u please explain the below clearly grep -i adding $logdir | grep -iv equation | awk '{print \$NF}' | sort -u | sed -e... (1 Reply)
Discussion started by: mail2sant
1 Replies

5. UNIX for Dummies Questions & Answers

Please explain this

if then echo "Syntax: $0 <sid> <COLD/HOT> <DEST>" exit fi if --------------what does this mean??? echo "Syntax: $0 <sid> <COLD/HOT> <DEST>"---pls explain this as well (2 Replies)
Discussion started by: appsdba.nitin
2 Replies

6. Shell Programming and Scripting

can any one explain this example

hi all i have an example i want one help me to understand cause i tried to test it but almost fail and i don't know how can i solve this problem " the main idea to read from two files and replace something from one to another " but i don't understand why it fail all time $ cat main.txt... (4 Replies)
Discussion started by: maxim42
4 Replies

7. Shell Programming and Scripting

Explain $# please

I'm trying to follow a script and I see it begins with this: if ; then if ; then print "blah $0 blah blah " exit fi fi What does $# mean? I found out that $1 refers to the shell environment and the last argument that was entered or passed in the previous command. I couldn't find $#... (2 Replies)
Discussion started by: MaindotC
2 Replies

8. Shell Programming and Scripting

anyone can explain this?

why the case 2 will happen ? , ' should stop the history substitution ,shouldn't it? case 1 # echo "123"|sed '/123/!d' 123 case 2 # echo "123 > 456 > 1 > "|sed '/123/!d' -bash: !d': event not found case 3 # echo "123 > 456 > 12 > "|sed '/123/'\!d 123 # bash --version (1 Reply)
Discussion started by: justlooks
1 Replies

9. Shell Programming and Scripting

Can someone explain this for me?

Can someone do me a favour and explain the following for me: ((r=$RANDOM%$n+1)) I know what $RANDOM does but what is % sign and what does it do with %$n+1? (2 Replies)
Discussion started by: bashily
2 Replies

10. UNIX for Dummies Questions & Answers

How I can explain this?

Hi friends! I'm learning UNIX and I have a small question. Working with Shell, i put the name of one executable (in c language) + one number and it says this: $ gcc misterioso_4.c $ ./misterioso_4 6 got: , I can not find an answer in the manual because I havent applied any variable.... (5 Replies)
Discussion started by: dakota
5 Replies

LEARN ABOUT DEBIAN

explain_waitpid_or_die

explain_waitpid_or_die(3)				     Library Functions Manual					 explain_waitpid_or_die(3)

NAME

       explain_waitpid_or_die - wait for process to change state and report errors

SYNOPSIS

       #include <libexplain/waitpid.h>
       int pid = explain_waitpid_or_die(int pid, int *status, int options);

DESCRIPTION

       The  explain_waitpid_or_die  function  is  used	to  call the waitpid(2) system call.  On failure an explanation will be printed to stderr,
       obtained from explain_waitpid(3), and then the process terminates by calling exit(EXIT_FAILURE).

       This function is intended to be used in a fashion similar to the following example:
	      explain_waitpid_or_die(pid, status, options);

       pid     The pid, exactly as to be passed to the waitpid(2) system call.

       status  The status, exactly as to be passed to the waitpid(2) system call.

       options The options, exactly as to be passed to the waitpid(2) system call.

       Returns:
	       This function only returns on success.  On failure, prints an explanation and exits.

SEE ALSO

       waitpid(2)
	       wait for process to change state

       explain_waitpid(3)
	       explain waitpid(2) errors

       exit(2) terminate the calling process

COPYRIGHT

       libexplain version 0.52
       Copyright (C) 2008 Peter Miller

															 explain_waitpid_or_die(3)
All times are GMT -4. The time now is 08:53 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy