dirs_links/list_files.c

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 2024, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

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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.

  Cover of The Linux Programming Interface
+/* 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>
+#endif
 #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);
         return;
     }
 
     /* 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)
             break;
 
         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)
         errExit("readdir");
 
     if (closedir(dirp) == -1)
         errMsg("closedir");
 }
 
 int
 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 */
         listFiles(".");
     else
         for (argv++; *argv; argv++)
             listFiles(*argv);
 
     exit(EXIT_SUCCESS);
 }

Note that, in most cases, the programs rendered in these web pages are not free standing: you'll typically also need a few other source files (mostly in the lib/ subdirectory) as well. Generally, it's easier to just download the entire source tarball and build the programs with make(1). By hovering your mouse over the various hyperlinked include files and function calls above, you can see which other source files this file depends on.

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