This is procexec/vfork_fd_test.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is the solution to Exercise 24-2 (page 530).

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.


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  Cover of The Linux Programming Interface

Function list (Bold in this list means a function is not static)

/* vfork_fd_test.c

   Demonstrate that a vfork()ed child has a separate set of file descriptors
   from its parent.
#define _BSD_SOURCE     /* To get vfork() declaration from <unistd.h>
                           in case _XOPEN_SOURCE >= 700 */
#include "tlpi_hdr.h"
main(int argc, char *argv[])
    switch (vfork()) {
    case -1: errExit("vfork");

    case 0: if (close(STDOUT_FILENO) == -1)
                errMsg("close - child");

    default: break;

    /* Now parent closes STDOUT_FILENO twice: only the second close
       should fail, indicating that the close(STDOUT_FILENO) by the
       child did not affect the parent. */

    if (close(STDOUT_FILENO) == -1)
    if (close(STDOUT_FILENO) == -1)



Download procexec/vfork_fd_test.c

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