This is svipc/t_ftok.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 45-2 (page 936).

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.


Download svipc/t_ftok.c

  Cover of The Linux Programming Interface

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

/* t_ftok.c

   Test the key values returned by ftok(3).

   Usage: t_ftok key-file key-char

   Simply calls ftok(), using the values supplied in the command-line arguments,
   and displays the resulting key.
#include <sys/ipc.h>
#include <sys/stat.h>
#include "tlpi_hdr.h"
main(int argc, char *argv[])
    if (argc != 3 || strcmp(argv[1], "--help") == 0)
        usageErr("%s file-name keychar\n", argv[0]);

    printf("Size of key_t = %ld bytes\n", (long) sizeof(key_t));

    struct stat sb;
    if (stat(argv[1], &sb) == -1)

    key_t key = ftok(argv[1], argv[2][0]);
    if (key == -1)

    printf("Key = %lx i-node = %lx st_dev = %lx proj = %x\n",
          (unsigned long) key, (unsigned long) sb.st_ino,
          (unsigned long) sb.st_dev, (unsigned int) argv[2][0]);
    if (key == -1)
        printf("File does not exist\n");



Download svipc/t_ftok.c

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