nftw(3) Library Functions Manual nftw(3)
NAME
nftw - Walks a file tree
LIBRARY
Standard C Library (libc.so, libc.a)
SYNOPSIS
#include <ftw.h>
int nftw(
const char *path,
int(*function)(const char *, const struct stat *,
int, struct FTW *),
int depth,
int flags);
The following definition of the nftw() function does not conform to current standards and is supported only for backward compatibility:
int nftw(
const char *path,
int(*function)(const char *, const struct stat *,
int, struct FTW),
int depth,
int flags);
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
nftw(): XSH5.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
PARAMETERS
Specifies the directory hierarchy to be searched. Specifies the function to be invoked for each object in the directory hierarchy. Limits
the directory depth for the search. At most one file descriptor will be used for each directory level.
In the backward-compatible version of nftw(), this parameter can be supplied but is not used. Specifies optional flags that modify
the operation of the nftw() function.
DESCRIPTION
The nftw() function recursively searches the directory hierarchy that descends from the directory specified by the path parameter. The
nftw() function performs the same operations as ftw(), except that it takes an additional argument flags, which is a bitwise inclusive-OR
of zero or more of the following flags: If set, nftw() changes the current working directory to each directory as it reports files in that
directory. If clear, nftw() does not change the current working directory. If set, nftw() reports all files in a directory before report-
ing the directory itself. If clear, nftw() reports any directory before reporting files in that directory. If set, nftw() reports only
files in the same file system as path. If clear, nftw() reports all files encountered during the walk. If set, nftw() performs a physi-
cal walk and does not follow symbolic links. If clear, nftw() follows links instead of reporting them, and does not report the same file
twice.
The nftw() function calls the function parameter with four arguments at each file and directory. The first argument is the pathname of the
object. The second argument points to the stat buffer containing information on the object. The third argument is an integer that identi-
fies the file type or condition of the object. The value of the integer is one of the following: A directory. A directory that cannot be
read. When nftw() reports this condition, function is not called for any of the directory's descendants. A directory whose subdirectories
have been visited. (This condition occurs only if the FTW_DEPTH flag is included in flags.) A regular file. An object for which the
stat() function failed because of lack of appropriate permission. The content of the stat() buffer passed to function is meaningless.
Failure of nftw() for any other reason is considered an error and results in a return value of -l.
A symbolic link. (This condition occurs only if the FTW_PHYS flag is included in flags.) A symbolic link that names a non-existent file.
(This condition occurs only if the FTW_PHYS flag is not included in flags.)
In the backward-compatible version of nftw, the FTW_SLN value is not used.
The fourth argument to function is a pointer to an FTW structure.
In the backward-compatible version of nftw(), the fourth argument is an FTW structure rather than a pointer to one.
The FTW structure includes the following members:
int base; int level;
The value of base is the offset into the pathname of the object. This pathname is passed as the first argument to the function parameter.
The value of level specifies the depth relative to the root of the walk, where the root level has a value of 0 (zero).
NOTES
[Tru64 UNIX] When compiled in the X/Open UNIX environment, calls to the nftw() function are internally renamed by prepending _E to the
function name. When debugging a module that includes the nftw() function and for which _XOPEN_SOURCE_EXTENDED has been defined, use _Enftw
to refer to the nftw() call. See standards(5) for information on when the _XOPEN_SOURCE_EXTENDED macro is defined.
[Tru64 UNIX] The nftw() function is reentrant; care should be taken to ensure that the function supplied as argument function is also
reentrant.
RETURN VALUES
If the directory hierarchy is completed, the nftw() function returns a value of 0 (zero).
If the function specified by the function parameter returns a nonzero value, the nftw() function stops the search and returns the value
that was returned by the function.
If the nftw() function detects an error other than [EACCES], a value of -1 is returned, and errno is set to indicate the error.
ERRORS
If any of the following conditions occurs, the nftw() function sets errno to the value that corresponds to the condition. Search permis-
sion is denied for any component of the path parameter or read permission is denied for the path parameter, or function returns -1 and does
not reset errno. The length of the path string exceeds PATH_MAX, or a pathname component is longer than NAME_MAX while _POSIX_NO_TRUNC is
in effect.
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX. The path parameter points to
the name of a file that does not exist or points to an empty string. A component of the path parameter is not a directory. [Tru64
UNIX] There is insufficient memory for this operation.
In addition, if the function pointed to by the function parameter encounters an error, errno may be set accordingly.
RELATED INFORMATION
Functions: stat(2), ftw(3)
Standards: standards(5) delim off
nftw(3)