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    The following form allows you to view linux man pages.

    Command:

    nftw

    
    
    

    SYNOPSIS

           #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 direc-
           tory 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).
    
           To avoid using up  all  of  the  calling  process's  file  descriptors,
           nopenfd  specifies  the  maximum  number of directories that ftw() will
           hold open simultaneously.  When the search depth  exceeds  this,  ftw()
           will  become slower because directories have to be closed and reopened.
           ftw() uses at most one file descriptor for each level in the  directory
           tree.
    
           For  each  entry  found  in the tree, ftw() calls fn() with three argu-
           ments: fpath, sb, and typeflag.  fpath is the pathname  of  the  entry,
           and is expressed either as a pathname relative to the calling process's
           current working directory at the time of the call to ftw(), if  dirpath
           was  expressed  as  a relative pathname, or as an absolute pathname, if
           dirpath was expressed as an absolute pathname.  sb is a pointer to  the
           stat structure returned by a call to stat(2) for fpath.  typeflag is an
           integer that has one of the following values:
    
           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.
                  The  probable cause for this is that the caller had read permis-
                  sion on the parent directory, so that the filename  fpath  could
                  be  seen,  but did not have execute permission, so that the file
                  could not be reached for stat(2).
    
                  If fpath is a symbolic link  and  stat(2)  failed,  POSIX.1-2001
    
       nftw()
           The function nftw() is the same as ftw(), except that it has one  addi-
           tional  argument, flags, and calls fn() with one more argument, ftwbuf.
    
           This flags argument is formed by ORing zero or more  of  the  following
           flags:
    
           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 argu-
                         ments 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.
    
                  Other return values could be associated with new actions in  the
                  future;  fn()  should  not return values other than those listed
                  above.
    
                  The feature test  macro  _GNU_SOURCE  must  be  defined  (before
                  including any header files) in order to obtain the definition of
                  FTW_ACTIONRETVAL from <ftw.h>.
    
           FTW_CHDIR
                  If set, do a chdir(2) to each directory before handling its con-
                  tents.   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
           same values as with ftw(), or any of the following values:
    
           FTW_DP fpath is a directory, and FTW_DEPTH was specified in flags.  (If
                  FTW_DEPTH  was  not  specified  in  flags, then directories will
                  always be visited with typeflag set to FTW_D.)  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.)
    
           The fourth argument that nftw() supplies when calling fn() is a  struc-
           ture of type FTW:
    
               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.
    
           If fn() returns nonzero, then the tree walk is terminated and the value
           returned by fn() is returned as the result of ftw() or nftw().
    
           If nftw() is called with  the  FTW_ACTIONRETVAL  flag,  then  the  only
           nonzero value that should be used by fn() to terminate the tree walk is
           FTW_STOP, and that value is returned as the result of nftw().
    
    
    

    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  pre-
           serve 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
    
       Program source
           #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)
    
    
    

    Linux 2014-01-11 FTW(3)

    
    
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