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File::Find(3)
NAME
find - traverse a file tree
finddepth - traverse a directory structure depth-first
SYNOPSIS
use File::Find;
find(<!>wanted, '/foo', '/bar');
sub wanted { ... }
use File::Find;
finddepth(<!>wanted, '/foo', '/bar');
sub wanted { ... }
use File::Find;
find({ wanted => <!>process, follow => 1 }, '.');
DESCRIPTION
The first argument to find() is either a hash reference describing the
operations to be performed for each file, or a code reference.
Here are the possible keys for the hash:
"wanted"
The value should be a code reference. This code reference is called 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 a directory; it is called after readdir() but before the loop
that calls the wanted() function. It is called with a list of strings
and is expected to return a list of strings. The code can be used to
sort the strings alphabetically, numerically, or to filter out directory
entries based on their name alone.
"postprocess"
The value should be a code reference. It is invoked just before leaving
the current directory. It is called in void context with no arguments.
The name of the current directory is in $File::Find::dir. This hook is
handy for summarizing a directory, such as calculating its disk usage.
"follow"
Causes symbolic links to be followed. Since directory trees with
symbolic links (followed) may contain files more than once and may even
have cycles, a hash has to be built up with an entry for each file.
This might be expensive both in space and time for a large directory
tree. See follow_fast and follow_skip below. If either follow or
follow_fast is in effect:
· It is guaranteed that an lstat has been called before the user's
wanted() function is called. This enables fast file checks
involving _.
· There is a variable "$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, 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"
"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 dirctories but to proceed normally otherwise.
"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 cd'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.
"untaint_pattern"
See above. This should be set using the "qr" quoting operator. The
default is set to "qr|^([-+@\w./]+)$|". Note that the parantheses are
vital.
"untaint_skip"
If set, directories (subtrees) which fail the untaint_pattern are
skipped. The default is to 'die' in such a case.
The wanted() function does whatever verifications you want.
"$File::Find::dir" contains the current directory name, and "$_" the
current filename within that directory. "$File::Find::name" contains the
complete pathname to the file. You are chdir()'d to "$File::Find::dir" when
the function is called, unless "no_chdir" was specified. When <follow> or
<follow_fast> are in effect, there is also a "$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);
}
Set the variable "$File::Find::dont_use_nlink" if you're using AFS, since
AFS cheats.
Here's another interesting wanted function. It will find all symlinks 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.
CAVEAT
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.
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