dirs_links/nftw_dir_tree.cThis is dirs_links/nftw_dir_tree.c (Listing 18-3, page 360), 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. This page shows the "distribution" or "book" version of the file (why are there two versions?), or the differences between the two versions. You can switch between the views using the tabs below. 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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/* nftw_dir_tree.c Demonstrate the use of nftw(3). Walk though the directory tree specified on the command line (or the current working directory if no directory is specified on the command line), displaying an indented hierarchy of files in the tree. For each file, display: * a letter indicating the file type (using the same letters as "ls -l"), as obtained using stat(2); * a string indicating the file type, as supplied by nftw(); and * the file's i-node number. */ #if defined(__sun) #define _XOPEN_SOURCE 500 /* Solaris 8 needs it this way */ #else #if ! defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600 #define _XOPEN_SOURCE 600 /* Get nftw() and S_IFSOCK declarations */ #endif #endif #include <ftw.h> #include "tlpi_hdr.h"
static void usageError(const char *progName, const char *msg) { if (msg != NULL) fprintf(stderr, "%s\n", msg); fprintf(stderr, "Usage: %s [-d] [-m] [-p] [directory-path]\n", progName); fprintf(stderr, "\t-d Use FTW_DEPTH flag\n"); fprintf(stderr, "\t-m Use FTW_MOUNT flag\n"); fprintf(stderr, "\t-p Use FTW_PHYS flag\n"); exit(EXIT_FAILURE); }
static int /* Function called by nftw() */ dirTree(const char *pathname, const struct stat *sbuf, int type, struct FTW *ftwb) { if (type == FTW_NS) { /* Could not stat() file */ printf("?"); } else { switch (sbuf->st_mode & S_IFMT) { /* Print file type */ case S_IFREG: printf("-"); break; case S_IFDIR: printf("d"); break; case S_IFCHR: printf("c"); break; case S_IFBLK: printf("b"); break; case S_IFLNK: printf("l"); break; case S_IFIFO: printf("p"); break; case S_IFSOCK: printf("s"); break; default: printf("?"); break; /* Should never happen (on Linux) */ } } printf(" %s ", (type == FTW_D) ? "D " : (type == FTW_DNR) ? "DNR" : (type == FTW_DP) ? "DP " : (type == FTW_F) ? "F " : (type == FTW_SL) ? "SL " : (type == FTW_SLN) ? "SLN" : (type == FTW_NS) ? "NS " : " "); if (type != FTW_NS) printf("%7ld ", (long) sbuf->st_ino); else printf(" "); printf(" %*s", 4 * ftwb->level, ""); /* Indent suitably */ printf("%s\n", &pathname[ftwb->base]); /* Print basename */ return 0; /* Tell nftw() to continue */ }
int main(int argc, char *argv[]) { int flags, opt; flags = 0; while ((opt = getopt(argc, argv, "dmp")) != -1) { switch (opt) { case 'd': flags |= FTW_DEPTH; break; case 'm': flags |= FTW_MOUNT; break; case 'p': flags |= FTW_PHYS; break; default: usageError(argv[0], NULL); } } if (argc > optind + 1) usageError(argv[0], NULL); if (nftw((argc > optind) ? argv[optind] : ".", dirTree, 10, flags) == -1) { perror("nftw"); exit(EXIT_FAILURE); } 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.