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File::Find(3p)	Perl Programmers Reference Guide   File::Find(3p)

NAME
     File::Find - Traverse a directory tree.

SYNOPSIS
	 use File::Find;
	 find(\&wanted, @directories_to_search);
	 sub wanted { ... }

	 use File::Find;
	 finddepth(\&wanted, @directories_to_search);
	 sub wanted { ... }

	 use File::Find;
	 find({ wanted => \&process, follow => 1 }, '.');

DESCRIPTION
     These are functions for searching through directory trees
     doing work on each file found similar to the Unix find com-
     mand.  File::Find exports two functions, "find" and
     "finddepth".  They work similarly but have subtle differ-
     ences.

     find
	   find(\&wanted,  @directories);
	   find(\%options, @directories);

	 "find()" does a depth-first search over the given
	 @directories in the order they are given.  For each file
	 or directory found, it calls the &wanted subroutine.
	 (See below for details on how to use the &wanted func-
	 tion).	 Additionally, for each directory found, it will
	 "chdir()" into that directory and continue the search,
	 invoking the &wanted function on each file or subdirec-
	 tory in the directory.

     finddepth
	   finddepth(\&wanted,	@directories);
	   finddepth(\%options, @directories);

	 "finddepth()" works just like "find()" except that is
	 invokes the &wanted function for a directory after
	 invoking it for the directory's contents.  It does a
	 postorder traversal instead of a preorder traversal,
	 working from the bottom of the directory tree up where
	 "find()" works from the top of the tree down.

     %options

     The first argument to "find()" is either a code reference to
     your &wanted function, or a hash reference describing the
     operations to be performed for each file.	The code refer-
     ence is described in "The wanted function" below.

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     Here are the possible keys for the hash:

     "wanted"
	The value should be a code reference.  This code refer-
	ence is described in "The wanted function" below.

     "bydepth"
	Reports the name of a directory only AFTER all its
	entries have been reported.  Entry point "finddepth()" is
	a shortcut for specifying "<{ bydepth =" 1 }>> in the
	first argument of "find()".

     "preprocess"
	The value should be a code reference. This code reference
	is used to preprocess the current directory. The name of
	the currently processed directory is in $File::Find::dir.
	Your preprocessing function is called after "readdir()",
	but before the loop that calls the "wanted()" function.
	It is called with a list of strings (actually
	file/directory names) and is expected to return a list of
	strings. The code can be used to sort the file/directory
	names alphabetically, numerically, or to filter out
	directory entries based on their name alone. When follow
	or follow_fast are in effect, "preprocess" is a no-op.

     "postprocess"
	The value should be a code reference. It is invoked just
	before leaving the currently processed directory. It is
	called in void context with no arguments. The name of the
	current directory is in $File::Find::dir. This hook is
	handy for summarizing a directory, such as calculating
	its disk usage. When follow or follow_fast are in effect,
	"postprocess" is a no-op.

     "follow"
	Causes symbolic links to be followed. Since directory
	trees with symbolic links (followed) may contain files
	more than once and may even have cycles, a hash has to be
	built up with an entry for each file. This might be
	expensive both in space and time for a large directory
	tree. See follow_fast and follow_skip below. If either
	follow or follow_fast is in effect:

	*     It is guaranteed that an lstat has been called
	      before the user's "wanted()" function is called.
	      This enables fast file checks involving _. Note
	      that this guarantee no longer holds if follow or
	      follow_fast are not set.

	*     There is a variable $File::Find::fullname which
	      holds the absolute pathname of the file with all
	      symbolic links resolved.	If the link is a dangling

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	      symbolic link, then fullname will be set to
	      "undef".

	This is a no-op on Win32.

     "follow_fast"
	This is similar to follow except that it may report some
	files more than once.  It does detect cycles, however.
	Since only symbolic links have to be hashed, this is much
	cheaper both in space and time.	 If processing a file
	more than once (by the user's "wanted()" function) is
	worse than just taking time, the option follow should be
	used.

	This is also a no-op on Win32.

     "follow_skip"
	"follow_skip==1", which is the default, causes all files
	which are neither directories nor symbolic links to be
	ignored if they are about to be processed a second time.
	If a directory or a symbolic link are about to be pro-
	cessed a second time, File::Find dies.

	"follow_skip==0" causes File::Find to die if any file is
	about to be processed a second time.

	"follow_skip==2" causes File::Find to ignore any dupli-
	cate files and directories but to proceed normally other-
	wise.

     "dangling_symlinks"
	If true and a code reference, will be called with the
	symbolic link name and the directory it lives in as argu-
	ments.	Otherwise, if true and warnings are on, warning
	"symbolic_link_name is a dangling symbolic link\n" will
	be issued.  If false, the dangling symbolic link will be
	silently ignored.

     "no_chdir"
	Does not "chdir()" to each directory as it recurses. The
	"wanted()" function will need to be aware of this, of
	course. In this case, $_ will be the same as
	$File::Find::name.

     "untaint"
	If find is used in taint-mode (-T command line switch or
	if EUID != UID or if EGID != GID) then internally direc-
	tory names have to be untainted before they can be
	chdir'ed to. Therefore they are checked against a regular
	expression untaint_pattern.  Note that all names passed
	to the user's wanted() function are still tainted. If
	this option is used while not in taint-mode, "untaint" is

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	a no-op.

     "untaint_pattern"
	See above. This should be set using the "qr" quoting
	operator. The default is set to	 "qr|^([-+@\w./]+)$|".
	Note that the parentheses are vital.

     "untaint_skip"
	If set, a directory which fails the untaint_pattern is
	skipped, including all its sub-directories. The default
	is to 'die' in such a case.

     The wanted function

     The "wanted()" function does whatever verifications you want
     on each file and directory.  Note that despite its name, the
     "wanted()" function is a generic callback function, and does
     not tell File::Find if a file is "wanted" or not.	In fact,
     its return value is ignored.

     The wanted function takes no arguments but rather does its
     work through a collection of variables.

     $File::Find::dir is the current directory name,
     $_ is the current filename within that directory
     $File::Find::name is the complete pathname to the file.

     Don't modify these variables.

     For example, when examining the file /some/path/foo.ext you
     will have:

	 $File::Find::dir  = /some/path/
	 $_		   = foo.ext
	 $File::Find::name = /some/path/foo.ext

     You are chdir()'d to $File::Find::dir when the function is
     called, unless "no_chdir" was specified. Note that when
     changing to directories is in effect the root directory (/)
     is a somewhat special case inasmuch as the concatenation of
     $File::Find::dir, '/' and $_ is not literally equal to
     $File::Find::name. The table below summarizes all variants:

		   $File::Find::name  $File::Find::dir	$_
      default	   /		      /			.
      no_chdir=>0  /etc		      /			etc
		   /etc/x	      /etc		x

      no_chdir=>1  /		      /			/
		   /etc		      /			/etc
		   /etc/x	      /etc		/etc/x

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     When <follow> or <follow_fast> are in effect, there is also
     a $File::Find::fullname.  The function may set
     $File::Find::prune to prune the tree unless "bydepth" was
     specified.	 Unless "follow" or "follow_fast" is specified,
     for compatibility reasons (find.pl, find2perl) there are in
     addition the following globals available:
     $File::Find::topdir, $File::Find::topdev,
     $File::Find::topino, $File::Find::topmode and
     $File::Find::topnlink.

     This library is useful for the "find2perl" tool, which when
     fed,

	 find2perl / -name .nfs\* -mtime +7 \
	     -exec rm -f {} \; -o -fstype nfs -prune

     produces something like:

	 sub wanted {
	     /^\.nfs.*\z/s &&
	     (($dev, $ino, $mode, $nlink, $uid, $gid) = lstat($_)) &&
	     int(-M _) > 7 &&
	     unlink($_)
	     ||
	     ($nlink || (($dev, $ino, $mode, $nlink, $uid, $gid) = lstat($_))) &&
	     $dev < 0 &&
	     ($File::Find::prune = 1);
	 }

     Notice the "_" in the above "int(-M _)": the "_" is a magi-
     cal filehandle that caches the information from the preced-
     ing "stat()", "lstat()", or filetest.

     Here's another interesting wanted function.  It will find
     all symbolic links that don't resolve:

	 sub wanted {
	      -l && !-e && print "bogus link: $File::Find::name\n";
	 }

     See also the script "pfind" on CPAN for a nice application
     of this module.

WARNINGS
     If you run your program with the "-w" switch, or if you use
     the "warnings" pragma, File::Find will report warnings for
     several weird situations. You can disable these warnings by
     putting the statement

	 no warnings 'File::Find';

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     in the appropriate scope. See perllexwarn for more info
     about lexical warnings.

CAVEAT
     $dont_use_nlink
       You can set the variable $File::Find::dont_use_nlink to 1,
       if you want to force File::Find to always stat direc-
       tories. This was used for file systems that do not have an
       "nlink" count matching the number of sub-directories.
       Examples are ISO-9660 (CD-ROM), AFS, HPFS (OS/2 file sys-
       tem), FAT (DOS file system) and a couple of others.

       You shouldn't need to set this variable, since File::Find
       should now detect such file systems on-the-fly and switch
       itself to using stat. This works even for parts of your
       file system, like a mounted CD-ROM.

       If you do set $File::Find::dont_use_nlink to 1, you will
       notice slow-downs.

     symlinks
       Be aware that the option to follow symbolic links can be
       dangerous. Depending on the structure of the directory
       tree (including symbolic links to directories) you might
       traverse a given (physical) directory more than once (only
       if "follow_fast" is in effect). Furthermore, deleting or
       changing files in a symbolically linked directory might
       cause very unpleasant surprises, since you delete or
       change files in an unknown directory.

NOTES
     +	 Mac OS (Classic) users should note a few differences:

	 +   The path separator is ':', not '/', and the current
	     directory is denoted as ':', not '.'. You should be
	     careful about specifying relative pathnames. While a
	     full path always begins with a volume name, a rela-
	     tive pathname should always begin with a ':'.  If
	     specifying a volume name only, a trailing ':' is
	     required.

	 +   $File::Find::dir is guaranteed to end with a ':'. If
	     $_ contains the name of a directory, that name may
	     or may not end with a ':'. Likewise,
	     $File::Find::name, which contains the complete path-
	     name to that directory, and $File::Find::fullname,
	     which holds the absolute pathname of that directory
	     with all symbolic links resolved, may or may not end
	     with a ':'.

	 +   The default "untaint_pattern" (see above) on Mac OS
	     is set to "qr|^(.+)$|". Note that the parentheses

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	     are vital.

	 +   The invisible system file "Icon\015" is ignored.
	     While this file may appear in every directory, there
	     are some more invisible system files on every
	     volume, which are all located at the volume root
	     level (i.e. "MacintoshHD:"). These system files are
	     not excluded automatically. Your filter may use the
	     following code to recognize invisible files or
	     directories (requires Mac::Files):

	      use Mac::Files;

	      # invisible() --	returns 1 if file/directory is invisible,
	      # 0 if it's visible or undef if an error occurred

	      sub invisible($) {
		my $file = shift;
		my ($fileCat, $fileInfo);
		my $invisible_flag =  1 << 14;

		if ( $fileCat = FSpGetCatInfo($file) ) {
		  if ($fileInfo = $fileCat->ioFlFndrInfo() ) {
		    return (($fileInfo->fdFlags & $invisible_flag) && 1);
		  }
		}
		return undef;
	      }

	     Generally, invisible files are system files, unless
	     an odd application decides to use invisible files
	     for its own purposes. To distinguish such files from
	     system files, you have to look at the type and crea-
	     tor file attributes. The MacPerl built-in functions
	     "GetFileInfo(FILE)" and "SetFileInfo(CREATOR, TYPE,
	     FILES)" offer access to these attributes (see
	     MacPerl.pm for details).

	     Files that appear on the desktop actually reside in
	     an (hidden) directory named "Desktop Folder" on the
	     particular disk volume. Note that, although all
	     desktop files appear to be on the same "virtual"
	     desktop, each disk volume actually maintains its own
	     "Desktop Folder" directory.

BUGS AND CAVEATS
     Despite the name of the "finddepth()" function, both
     "find()" and "finddepth()" perform a depth-first search of
     the directory hierarchy.

HISTORY
     File::Find used to produce incorrect results if called

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     recursively. During the development of perl 5.8 this bug was
     fixed. The first fixed version of File::Find was 1.01.

perl v5.8.8		   2005-02-05				8

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