phpman > perldoc > File::Find(3perl)

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* command. File::Find exports two functions, "find" and "finddepth". They work
    similarly but have subtle differences.

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

        "finddepth()" works just like "find()" except that it 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.

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

  %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 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 reference is described in "The wanted
        function" below. The &wanted subroutine is mandatory.

    "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 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 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"
        Specifies what to do with symbolic links whose target doesn't exist. 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, a warning of the form
        ""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 directory names have to be untainted before they can be "chdir"'d 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.

    "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.

    The above variables have all been localized and may be changed without affecting data outside of
    the wanted function.

    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 (distributed as part of the App-find2perl CPAN
    distribution), 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";
        }

    Note that you may mix directories and (non-directory) files in the list of directories to be
    searched by the "wanted()" function.

        find(\&wanted, "./foo", "./bar", "./baz/epsilon");

    In the example above, no file in ./baz/ other than ./baz/epsilon will be evaluated by
    "wanted()".

    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';

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

BUGS AND CAVEATS
    $dont_use_nlink
        You can set the variable $File::Find::dont_use_nlink to 0 if you are sure the filesystem you
        are scanning reflects the number of subdirectories in the parent directory's "nlink" count.

        If you do set $File::Find::dont_use_nlink to 0, you may notice an improvement in speed at
        the risk of not recursing into subdirectories if a filesystem doesn't populate "nlink" as
        expected.

        $File::Find::dont_use_nlink now defaults to 1 on all platforms.

    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.

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.

SEE ALSO
    find(1), find2perl.