file::find(3)

NAME

File::Find - Traverse a directory tree.

SYNOPSIS

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 }, '.');

DESCRIPTION

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
"finddepth". They work similarly but have subtle differ
ences.

find: 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 subrou tine is called (see below for details). Additionally, for each directory found it will go into that direc tory and continue the search.
finddepth: 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.
%options
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:
"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 refer
ence 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, "pre process" 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 _.; � There is a variable $File::Find::fullname which
holds the absolute pathname of the file with all
symbolic links resolved
"follow_fast": This is similar to follow except that it may report
some files more than once. It does detect cycles, how
ever. Since only symbolic links have to be hashed,
this is much cheaper both in space and time. If pro
cessing 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": "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 sec
ond time. If a directory or a symbolic link are about
to be processed a second time, File::Find dies. "fol
low_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.
"dangling_symlinks": If true and a code reference, will be called with the
symbolic link name and the directory it lives in as
arguments. Otherwise, if true and warnings are on,
warning "symbolic_link_name is a dangling symbolic
link0 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
directory names have to be untainted before they can be
chdir'ed to. Therefore they are checked against a regu
lar 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.
"untaint_pattern": See above. This should be set using the "qr" quoting
operator. The default is set to "qr|^([-+@168
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. 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 concatena tion 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 $File::Find::topnlink.
This library is useful for the "find2perl" tool, which when fed,: find2perl / -name .nfs-mtime +7 -exec; rm -f {} ; -o -fstype nfs -prune
produces something like:: sub wanted {
/^.nfs.*s &&
(($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 mag ical filehandle that caches the information from the pre ceding 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::name0;; }
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 warn ings by putting the statement: no warnings 'File::Find';
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
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-thefly 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 cur
rent directory is denoted as ':', not '.'. You
should be careful about specifying relative path
names. 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.; � $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 $File::Find::full
name, which holds the absolute pathname of that
directory with all symbolic links resolved, may or
may not end with a ':'.; � The default "untaint_pattern" (see above) on Mac
OS is set to "qr|^(.+)$|". Note that the parenthe
ses are vital.; � The invisible system file "Icon 15" 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 & $invisi

ble_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 "Set
FileInfo(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 "vir
tual" desktop, each disk volume actually maintains
its own "Desktop Folder" directory.

HISTORY

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

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