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Flow of the fork, how many forks do I have?


Flow of the fork, how many forks do I have?

By : Tavo
Date : November 20 2020, 11:01 PM
wish help you to fix your issue execl does not return, it replaces the entire process image with /bin/echo. There are therefore zero "bar"s.
code :
    if (execl("/bin/echo", "/bin/echo", "foo", 0) == -1) {
      fork();
    }
    /* Not reached if execl succeeded.
    Because the exec family of functions replace the process image with
    another executable.  Flow will never return, unless there is an
    error. */
    printf("bar\n");
  int p;
  p = fork();
  /* Two processes now */
  if (fork()==0) {
      /* Two child processes here. */
      execl("/bin/echo", "/bin/echo", "foo", 0); /* (Simplification) */
      /* Two (/bin/echo foo) here, flow will never return back */
  }
int p;
p = fork();
/* if block removed for simplicity */
if (p != 0)
{
    /* Only the initial parent process. */
    execl("/bin/echo", "/bin/echo", "baz", 0);
}


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Unix fork tree that only forks on one child

Unix fork tree that only forks on one child


By : reza
Date : March 29 2020, 07:55 AM
I hope this helps you . Your left child should not continue the loop; it should break out of the loop, or exit. It has no children, but that simply means the wait() call will return with an error each time.
Your right child should continue the loop to continue the process down to the last level.
code :
I am the parent process with and id of: 13277
Level is 0, I am Left  child 13278, my parent is 13277
Exiting: 13278
Level is 0, I am Right child 13279, my parent is 13277
Level is 1, I am Left  child 13280, my parent is 13279
Level is 1, I am Right child 13281, my parent is 13279
Exiting: 13280
Level is 2, I am Right child 13283, my parent is 13281
Level is 2, I am Left  child 13282, my parent is 13281
Exiting: 13282
Level is 3, I am Left  child 13284, my parent is 13283
Level is 3, I am Right child 13285, my parent is 13283
Exiting: 13284
Level is 4, I am Left  child 13286, my parent is 13285
Exiting: 13286
Level is 4, I am Right child 13287, my parent is 13285
Level is 5, I am Left  child 13288, my parent is 13287
Exiting: 13288
Level is 5, I am Right child 13289, my parent is 13287
Level is 6, I am Right child 13291, my parent is 13289
Level is 6, I am Left  child 13290, my parent is 13289
Exiting: 13290
Exiting: 13291
Exiting: 13289
Exiting: 13287
Exiting: 13285
Exiting: 13283
Exiting: 13281
Exiting: 13279
Exiting: 13277
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

static void run_process(const char *child, int level)
{
    fprintf(stderr, "Level is %d, I am %-5s child %ld, my parent is %ld\n",
            level, child, (long)getpid(), (long)getppid());
}

int main(void)
{   
    int max = 7;

    fprintf(stderr, "I am the parent process with and id of: %ld\n", (long)getpid());

    for (int level = 0; level < max; level++)
    {
        pid_t leftchild;
        pid_t rightchild;
        if ((leftchild = fork()) < 0)
        {   
            fprintf(stderr, "can't fork, error %d\n", errno);
            exit(EXIT_FAILURE);
        }
        else if (leftchild == 0)
        {
            run_process("Left", level);
            break;
        }
        else if ((rightchild = fork()) < 0)
        {   
            fprintf(stderr, "can't fork, error %d\n", errno);
            exit(EXIT_FAILURE);
        }
        else if (rightchild == 0)
        {
            run_process("Right", level);
            continue;
        }
        else
            break;
    }

    wait(NULL);
    wait(NULL);
    fprintf(stderr, "Exiting: %ld\n", (long)getpid());

    return(0);
}
Why does GNU script use two forks instead of select and one fork?

Why does GNU script use two forks instead of select and one fork?


By : Laban
Date : March 29 2020, 07:55 AM
it should still fix some issue I just realised that the "script" binary on GNU linux is using two forks instead of one. It could simply use select instead of doing a first fork(). Why would it use two forks ? , The clue is in the code, which I have added some comments to.
code :
child = fork();
sigprocmask(SIG_SETMASK, &unblock_mask, NULL);

if (child < 0) {
    warn(_("fork failed"));
    fail();
}
if (child == 0) {
            /* child of first fork */
    sigprocmask(SIG_SETMASK, &block_mask, NULL);
    subchild = child = fork();
    sigprocmask(SIG_SETMASK, &unblock_mask, NULL);

    if (child < 0) {
        warn(_("fork failed"));
        fail();
    }
    if (child) {
                    /* child of second fork runs 'dooutput' */
        if (!timingfd)
            timingfd = fdopen(STDERR_FILENO, "w");
        dooutput(timingfd);
    } else
                    /* parent of second fork runs 'doshell' */
        doshell();
} else {
    sa.sa_handler = resize;
    sigaction(SIGWINCH, &sa, NULL);
}
    /* parent of first fork runs doinput */
doinput();
Does BitBucket allow fork to be created from existing forks?

Does BitBucket allow fork to be created from existing forks?


By : Vimal Kumar Prajapat
Date : March 29 2020, 07:55 AM
Does that help I found the answer myself and tested the same.
Yes, the approach is correct The option to create a fork was not visible since it was disabled in the "Repositories Settings" page. This page is accessed via the "Settings" link. The forking parameter was set to "No forks". I changed it to "Allow only private forks".
What happens if I remove a fork with forks from Github?

What happens if I remove a fork with forks from Github?


By : Cristian Guerra
Date : March 29 2020, 07:55 AM
should help you out What happens to forks when a repository is deleted or changes visibility?:
Deleting a private repository
How to specify fork/remote when passing branch names? For example when trying to rebase between forks?

How to specify fork/remote when passing branch names? For example when trying to rebase between forks?


By : user2976935
Date : March 29 2020, 07:55 AM
I hope this helps you . TL;DR
If you call your coworker's remote coworkerFork, their branch feature will be called coworkerFork/feature.
code :
git remote add coworkerFork <URL>
git fetch coworkerFork
git checkout coworkerFork/feature
git checkout -b coworker-feature
git rebase feature
git checkout feature
git merge coworker-feature
git branch -d coworker-feature
git cherry-pick <sha1 of the bug fix commits you want>
git merge coworkerFork/feature
git rebase coworkerFork/feature
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