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FTW(3) | Linux Programmer's Manual | FTW(3) |
NAME¶
ftw, nftw - file tree walkSYNOPSIS¶
#include <ftw.h>int ftw(const char *dirpath, int (*fn) (const char *fpath, const struct stat *sb, int typeflag), int nopenfd);#define _XOPEN_SOURCE 500 /* See feature_test_macros(7) */ #include <ftw.h>int nftw(const char *dirpath, int (*fn) (const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftwbuf), int nopenfd, int flags);
DESCRIPTION¶
ftw() walks through the directory tree that is located under the directory dirpath, and calls fn() once for each entry in the tree. By default, directories are handled before the files and subdirectories they contain (preorder traversal).- FTW_F
- fpath is a regular file.
- FTW_D
- fpath is a directory.
- FTW_DNR
- fpath is a directory which can't be read.
- FTW_NS
- The stat(2) call failed on fpath, which is
not a symbolic link.
nftw()¶
The function nftw() is the same as ftw(), except that it has one additional argument, flags, and calls fn() with one more argument, ftwbuf.- FTW_ACTIONRETVAL (since glibc 2.3.3)
- If this glibc-specific flag is set, then nftw() handles the return value from fn() differently. fn() should return one of the following values:
- FTW_CONTINUE
- Instructs nftw() to continue normally.
- FTW_SKIP_SIBLINGS
- If fn() returns this value, then siblings of the current entry will be skipped, and processing continues in the parent.
- FTW_SKIP_SUBTREE
- If fn() is called with an entry that is a directory ( typeflag is FTW_D), this return value will prevent objects within that directory from being passed as arguments to fn(). nftw() continues processing with the next sibling of the directory.
- FTW_STOP
- Causes nftw() to return immediately with the return value FTW_STOP.
- FTW_CHDIR
- If set, do a chdir(2) to each directory before handling its contents. This is useful if the program needs to perform some action in the directory in which fpath resides.
- FTW_DEPTH
- If set, do a post-order traversal, that is, call fn() for the directory itself after handling the contents of the directory and its subdirectories. (By default, each directory is handled before its contents.)
- FTW_MOUNT
- If set, stay within the same file system (i.e., do not cross mount points).
- FTW_PHYS
- If set, do not follow symbolic links. (This is what you
want.) If not set, symbolic links are followed, but no file is reported
twice.
- FTW_DP
- fpath is a directory, and FTW_DEPTH was specified in flags. All of the files and subdirectories within fpath have been processed.
- FTW_SL
- fpath is a symbolic link, and FTW_PHYS was set in flags.
- FTW_SLN
- fpath is a symbolic link pointing to a nonexistent file. (This occurs only if FTW_PHYS is not set.)
struct FTW { int base; int level; };
base is the offset of the filename (i.e., basename component) in the pathname given in fpath. level is the depth of fpath in the directory tree, relative to the root of the tree (dirpath, which has depth 0).
RETURN VALUE¶
These functions return 0 on success, and -1 if an error occurs.CONFORMING TO¶
POSIX.1-2001, SVr4, SUSv1. POSIX.1-2008 marks ftw() as obsolete.NOTES¶
POSIX.1-2001 note that the results are unspecified if fn does not preserve the current working directory. The function nftw() and the use of FTW_SL with ftw() were introduced in SUSv1. On some systems ftw() will never use FTW_SL, on other systems FTW_SL occurs only for symbolic links that do not point to an existing file, and again on other systems ftw() will use FTW_SL for each symbolic link. For predictable control, use nftw(). Under Linux, libc4 and libc5 and glibc 2.0.6 will use FTW_F for all objects (files, symbolic links, FIFOs, etc.) that can be stat'ed but are not a directory.EXAMPLE¶
The following program traverses the directory tree under the path named in its first command-line argument, or under the current directory if no argument is supplied. It displays various information about each file. The second command-line argument can be used to specify characters that control the value assigned to the flags argument when calling nftw().#define _XOPEN_SOURCE 500 #include <ftw.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> static int display_info(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftwbuf) { printf("%-3s %2d %7jd %-40s %d %s\n", (tflag == FTW_D) ? "d" : (tflag == FTW_DNR) ? "dnr" : (tflag == FTW_DP) ? "dp" : (tflag == FTW_F) ? "f" : (tflag == FTW_NS) ? "ns" : (tflag == FTW_SL) ? "sl" : (tflag == FTW_SLN) ? "sln" : "???", ftwbuf->level, (intmax_t) sb->st_size, fpath, ftwbuf->base, fpath + ftwbuf->base); return 0; /* To tell nftw() to continue */ } int main(int argc, char *argv[]) { int flags = 0; if (argc > 2 && strchr(argv[2], 'd') != NULL) flags |= FTW_DEPTH; if (argc > 2 && strchr(argv[2], 'p') != NULL) flags |= FTW_PHYS; if (nftw((argc < 2) ? "." : argv[1], display_info, 20, flags) == -1) { perror("nftw"); exit(EXIT_FAILURE); } exit(EXIT_SUCCESS); }
SEE ALSO¶
stat(2), fts(3), readdir(3)COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2010-09-20 | Linux |