


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


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 refer-
          ence 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().

       `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:

          o     It is guarantueed that an lstat has been called
                before the user's wanted() function 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

       `follow_fast'
          This is similar to follow except that it may report



2000-04-06                 perl v5.6.0                          1





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


          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
          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 paranthesis which 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 speci-
       fied, for compatibility reasons (find.pl, find2perl) there
       are in addition the following globals available:



2000-04-06                 perl v5.6.0                          2





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


       `$File::Find::topdir', `$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 symblic 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.












2000-04-06                 perl v5.6.0                          3


