File::Find - Traverse a directory tree. |
File::Find - Traverse a directory tree.
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 }, '.');
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 differences.
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
function). Additionally, for each directory found, it will
chdir()
into that directory and continue the search, invoking the
&wanted
function on each file or subdirectory in the directory.
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.
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 reference is described in The wanted function below.
Here are the possible keys for the hash:
wanted
bydepth
finddepth()
is a shortcut for
specifying <{ bydepth =
1 }>> in the first argument of find()
.
preprocess
$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
$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
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
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 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.
dangling_symlinks
no_chdir
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 $File::Find::name
.
untaint
untaint
is a no-op.
untaint_pattern
qr
quoting operator.
The default is set to qr|^([-+@\w./]+)$|
.
Note that the parentheses are vital.
untaint_skip
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
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 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 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.
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';
in the appropriate scope. See the perllexwarn manpage for more info about lexical warnings.
$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.
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.
$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 $File::Find::fullname
, which holds
the absolute pathname of that directory with all symbolic links resolved,
may or may not end with a ':'.
The default untaint_pattern
(see above) on Mac OS is set to
qr|^(.+)$|
. Note that the parentheses 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 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 maintains its own ``Desktop Folder'' directory.
Despite the name of the finddepth()
function, both find()
and
finddepth()
perform a depth-first search of the directory
hierarchy.
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.
File::Find - Traverse a directory tree. |