This is dirs_links/list_files.c (Listing 18-2, page 356), an example from the book, The Linux Programming Interface.

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

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  Cover of The Linux Programming Interface

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

/* list_files.c

   Demonstrate the use of opendir() and related functions to list files
   in a directory.

   Walk through each directory named on the command line (current directory
   if none are specified) to display a list of the files it contains.

    Usage: list_files [dir...]
#if defined(__APPLE__)
        /* Darwin requires this header before including <dirent.h> */
#include <sys/types.h>
#include <dirent.h>
#include "tlpi_hdr.h"
static void             /* List all files in directory 'dirpath' */
listFiles(const char *dirpath)
    DIR *dirp;
    struct dirent *dp;
    Boolean isCurrent;          /* True if 'dirpath' is "." */

    isCurrent = strcmp(dirpath, ".") == 0;

    dirp = opendir(dirpath);
    if (dirp  == NULL) {
        errMsg("opendir failed on '%s'", dirpath);

    /* For each entry in this directory, print directory + filename */

    for (;;) {
        errno = 0;              /* To distinguish error from end-of-directory */
        dp = readdir(dirp);
        if (dp == NULL)

        if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0)
            continue;           /* Skip . and .. */

        if (!isCurrent)
            printf("%s/", dirpath);
        printf("%s\n", dp->d_name);

    if (errno != 0)

    if (closedir(dirp) == -1)
main(int argc, char *argv[])
    if (argc > 1 && strcmp(argv[1], "--help") == 0)
        usageErr("%s [dir-path...]\n", argv[0]);

    if (argc == 1)              /* No arguments - use current directory */
        for (argv++; *argv; argv++)



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