Unix/Linux Go Back    

RedHat 9 (Linux i386) - man page for file::find (redhat section 3pm)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)

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

       File::Find - Traverse a directory tree.

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

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

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

       These are functions for searching through directory trees doing work on each file found
       similar to the Unix find command.  File::Find exports two functions, "find" and "find-
       depth".	They work similarly but have subtle differences.

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

	   find() does a breadth-first search over the given @directories in the order they are
	   given.  In essense, it works from the top down.

	   For each file or directory found the &wanted subroutine is called (see below for
	   details).  Additionally, for each directory found it will go into that directory and
	   continue the search.

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

	   finddepth() works just like find() except it does a depth-first search.  It works from
	   the bottom of the directory tree up.


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

       Here are the possible keys for the hash:

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

	  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().

	  The value should be a code reference. This code reference is used to preprocess the
	  current directory. The name of 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

	  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 direc-
	  tory, such as calculating its disk usage. When follow or follow_fast are in effect,
	  "postprocess" is a no-op.

	  Causes symbolic links to be followed. Since directory trees with symbolic links (fol-
	  lowed) 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:

	  o	It is guaranteed that an lstat has been called before the user's wanted() func-
		tion is called. This enables fast file checks involving  _.

	  o	There is a variable $File::Find::fullname which holds the absolute pathname of
		the file with all symbolic links resolved

	  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.

	  "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 processed 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 duplicate files and directories
	  but to proceed normally otherwise.

	  If true and a code reference, will be called with the symbolic link name and the direc-
	  tory it lives in as arguments.  Otherwise, if true and warnings are on, warning "sym-
	  bolic_link_name is a dangling symbolic link\n" will be issued.  If false, the dangling
	  symbolic link will be silently ignored.

	  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.

	  If find is used in taint-mode (-T command line switch or if EUID != UID or if EGID !=
	  GID) then internally directory 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 a no-op.

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

	  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.  It
       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

       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 &&
	       ($nlink || (($dev, $ino, $mode, $nlink, $uid, $gid) = lstat($_))) &&
	       $dev < 0 &&
	       ($File::Find::prune = 1);

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

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

	   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.

       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 warn-
       ings by putting the statement

	   no warnings 'File::Find';

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

	 You can set the variable $File::Find::dont_use_nlink to 1, if you want to force
	 File::Find to always stat directories. 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 system), 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.

	 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 tra-
	 verse 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.

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

	   o   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 relative pathname should always begin
	       with a ':'.  If specifying a volume name only, a trailing ':' is required.

	   o   $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 pathname 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 ':'.

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

	   o   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 creator 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 main-
	       tains its own "Desktop Folder" directory.

       File::Find used to produce incorrect results if called recursively.  During the develop-
       ment of perl 5.8 this bug was fixed.  The first fixed version of File::Find was 1.01.

perl v5.8.0				    2002-06-01				  File::Find(3pm)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums

All times are GMT -4. The time now is 02:12 AM.