1File::Finder::Steps(3)User Contributed Perl DocumentationFile::Finder::Steps(3)
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NAME

6       File::Finder::Steps - steps for File::Finder
7

SYNOPSIS

9         ## See File::Finder for normal use of steps
10
11         ## subclassing example:
12         BEGIN {
13           package My::File::Finder;
14           use base File::Finder;
15
16           sub _steps_class { "My::File::Finder::Steps" }
17         }
18         BEGIN {
19           package My::File::Finder::Steps;
20           use base File::Finder::Steps;
21
22           sub bigger_than { # true if bigger than N bytes
23             my $self = shift;
24             my $bytes = shift;
25             return sub {
26               -s > $bytes;
27             }
28           }
29         }
30
31         my $over_1k = My::File::Finder->bigger_than(1024);
32         print "Temp files over 1k:\n";
33         $over_1k->ls->in("/tmp");
34

DESCRIPTION

36       "File::Finder::Steps" provide the predicates being tested for
37       "File::Finder".
38
39   STEPS METHODS
40       These methods are called on a class or instance to add a "step".  Each
41       step adds itself to a list of steps, returning the new object.  This
42       allows you to chain steps together to form a formula.
43
44       As in find, the default operator is "and", and short-circuiting is
45       performed.
46
47       or  Like find's "or".
48
49       left
50           Like a left parenthesis.  Used in nesting pairs with "right".
51
52       right
53           Like a right parenthesis.  Used in nesting pairs with "left".  For
54           example:
55
56             my $big_or_old = File::Finder
57               ->type('f')
58               ->left
59                 ->size("+100")->or->mtime("+90")
60               ->right;
61             find($big_or_old->ls, "/tmp");
62
63           You need parens because the "or" operator is lower precedence than
64           the implied "and", for the same reason you need them here:
65
66             find /tmp -type f '(' -size +100 -o -mtime +90 ')' -print
67
68           Without the parens, the -type would bind to -size, and not to the
69           choice of -size or -mtime.
70
71           Mismatched parens will not be found until the formula is used,
72           causing a fatal error.
73
74       begin
75           Alias for "left".
76
77       end Alias for "right".
78
79       not Like find's "!".  Prefix operator, can be placed in front of
80           individual terms or open parens.  Can be nested, but what's the
81           point?
82
83             # list all non-files in /tmp
84             File::Finder->not->type('f')->ls->in("/tmp");
85
86       true
87           Always returns true.  Useful when a subexpression might fail, but
88           you don't want the overall code to fail:
89
90             ... ->left-> ...[might return false]... ->or->true->right-> ...
91
92           Of course, this is the find command's idiom of:
93
94              find .... '(' .... -o -true ')' ...
95
96       false
97           Always returns false.
98
99       comma
100           Like GNU find's ",".  The result of the expression (or
101           subexpression if in parens) up to this point is discarded, and
102           execution continues afresh.  Useful when a part of the expression
103           is needed for its side effects, but shouldn't affect the rest of
104           the "and"-ed chain.
105
106             # list all files and dirs, but don't descend into CVS dir contents:
107             File::Finder->type('d')->name('CVS')->prune->comma->ls->in('.');
108
109       follow
110           Enables symlink following, and returns true.
111
112       name(NAME)
113           True if basename matches NAME, which can be given as a glob pattern
114           or a regular expression object:
115
116             my $pm_files = File::Finder->name('*.pm')->in('.');
117             my $pm_files_too = File::Finder->name(qr/pm$/)->in('.');
118
119       perm(PERMISSION)
120           Like find's "-perm".  Leading "-" means "all of these bits".
121           Leading "+" means "any of these bits".  Value is de-octalized if a
122           leading 0 is present, which is likely only if it's being passed as
123           a string.
124
125             my $files = File::Finder->type('f');
126             # find files that are exactly mode 644
127             my $files_644 = $files->perm(0644);
128             # find files that are at least world executable:
129             my $files_world_exec = $files->perm("-1");
130             # find files that have some executable bit set:
131             my $files_exec = $files->perm("+0111");
132
133       type(TYPE)
134           Like find's "-type".  All native Perl types are supported.  Note
135           that "s" is a socket, mapping to Perl's "-S", to be consistent with
136           find.  Returns true or false, as appropriate.
137
138       print
139           Prints the fullname to "STDOUT", followed by a newline.  Returns
140           true.
141
142       print0
143           Prints the fullname to "STDOUT", followed by a NUL.  Returns true.
144
145       fstype
146           Not implemented yet.
147
148       user(USERNAME|UID)
149           True if the owner is USERNAME or UID.
150
151       group(GROUPNAME|GID)
152           True if the group is GROUPNAME or GID.
153
154       nouser
155           True if the entry doesn't belong to any known user.
156
157       nogroup
158           True if the entry doesn't belong to any known group.
159
160       links( +/- N )
161           Like find's "-links N".  Leading plus means "more than", minus
162           means "less than".
163
164       inum( +/- N )
165           True if the inode number meets the qualification.
166
167       size( +/- N [c/k])
168           True if the file size meets the qualification.  By default, N is in
169           half-K blocks.  Append a trailing "k" to the number to indicate 1K
170           blocks, or "c" to indicate characters (bytes).
171
172       atime( +/- N )
173           True if access time (in days) meets the qualification.
174
175       mtime( +/- N )
176           True if modification time (in days) meets the qualification.
177
178       ctime( +/- N )
179           True if inode change time (in days) meets the qualification.
180
181       exec(@COMMAND)
182           Forks the child process via "system()".  Any appearance of "{}" in
183           any argument is replaced by the current filename.  Returns true if
184           the child exit status is 0.  The list is passed directly to
185           "system", so if it's a single arg, it can contain "/bin/sh" syntax.
186           Otherwise, it's a pre-parsed command that must be found on the
187           PATH.
188
189           Note that I couldn't figure out how to horse around with the
190           current directory very well, so I'm using $_ here instead of the
191           more traditional "File::Find::name".  It still works, because we're
192           still chdir'ed down into the directory, but it looks weird on a
193           trace.  Trigger "no_chdir" in "find" if you want a traditional find
194           full path.
195
196             my $f = File::Finder->exec('ls', '-ldg', '{}');
197             find({ no_chdir => 1, wanted => $f }, @starting_dirs);
198
199           Yeah, it'd be trivial for me to add a no_chdir method.  Soon.
200
201       ok(@COMMAND)
202           Like "exec", but displays the command line first, and waits for a
203           response.  If the response begins with "y" or "Y", runs the
204           command.  If the command fails, or the response wasn't yes, returns
205           false, otherwise true.
206
207       prune
208           Sets $File::Find::prune, and returns true.
209
210       xdev
211           Not yet implemented.
212
213       newer
214           Not yet implemented.
215
216       eval(CODEREF)
217           Ah yes, the master escape, with extra benefits.  Give it a coderef,
218           and it evaluates that code at the proper time.  The return value is
219           noted for true/false and used accordingly.
220
221             my $blaster = File::Finder->atime("+30")->eval(sub { unlink });
222
223           But wait, there's more.  If the parameter is an object that
224           responds to "as_wanted", that method is automatically called,
225           hoping for a coderef return. This neat feature allows subroutines
226           to be created and nested:
227
228             my $old = File::Finder->atime("+30");
229             my $big = File::Finder->size("+100");
230             my $old_or_big = File::Finder->eval($old)->or->eval($big);
231             my $killer = File::Finder->eval(sub { unlink });
232             my $kill_old_or_big = File::Finder->eval($old_or_big)->ls->eval($killer);
233             $kill_old_or_big->in('/tmp');
234
235           Almost too cool for words.
236
237       depth
238           Like find's "-depth".  Sets a flag for "as_options", and returns
239           true.
240
241       ls  Like find's "-ls".  Performs a "ls -dils" on the entry to "STDOUT"
242           (without forking), and returns true.
243
244       tar Not yet implemented.
245
246       [n]cpio
247           Not yet implemented.
248
249       ffr($ffr_object)
250           Incorporate a "File::Find::Rule" object as a step. Note that this
251           must be a rule object, and not a result, so don't call or pass
252           "in".  For example, using "File::Find::Rule::ImageSize" to define a
253           predicate for image files that are bigger than a megapixel in my
254           friends folder, I get:
255
256             require File::Finder;
257             require File::Find::Rule;
258             require File::Find::Rule::ImageSize;
259             my $ffr = File::Find::Rule->file->image_x('>1000')->image_y('>1000');
260             my @big_friends = File::Finder->ffr($ffr)
261               ->in("/Users/merlyn/Pictures/Sorted/Friends");
262
263       contains(pattern)
264           True if the file contains "pattern" (either a literal string
265           treated as a regex, or a true regex object).
266
267             my $plugh_files = File::Finder->type('f')->contains(qr/plugh/);
268
269           Searching is performed on a line-by-line basis, respecting the
270           current value of $/.
271
272   EXTENDING
273       A step consists of a compile-time and a run-time component.
274
275       During the creation of a "File::Finder" object, step methods are called
276       as if they were methods against the slowly-growing "File::Finder"
277       instance, including any additional parameters as in a normal method
278       call.  The step is expected to return a coderef (possibly a closure) to
279       be executed at run-time.
280
281       When a "File::Finder" object is being evaluated as the "File::Find"
282       "wanted" routine, the collected coderefs are evaluated in sequence,
283       again as method calls against the "File::Finder" object.  No additional
284       parameters are passed.  However, the normal "wanted" values are
285       available, such as $_, $File::Find::name, and so on.  The "_" pseudo-
286       handle has been set properly, so you can safely use "-X" filetests and
287       "stat" against the pseudo-handle.  The routine is expected to return a
288       true/false value, which becomes the value of the step.
289
290       Although a "File::Finder" object is passed both to the compile-time
291       invocation and the resulting run-time invocation, only the "options"
292       self-hash element is properly duplicated through the cloning process.
293       Do not be tempted to add additional self-hash elements without
294       overriding "File::Finder"'s "_clone".  Instead, pass values from the
295       compile-time phase to the run-time phase using closure variables, as
296       shown in the synopsis.
297
298       For simplicity, you can also just mix-in your methods to the existing
299       "File::Finder::Steps" class, rather than subclassing both classes as
300       shown above.  However, this may result in conflicting implementations
301       of a given step name, so beware.
302

SEE ALSO

304       File::Finder
305

BUGS

307       None known yet.
308

AUTHOR

310       Randal L. Schwartz, <merlyn@stonehenge.com>
311
313       Copyright (C) 2003,2004 by Randal L. Schwartz, Stonehenge Consulting
314       Services, Inc.
315
316       This library is free software; you can redistribute it and/or modify it
317       under the same terms as Perl itself, either Perl version 5.8.2 or, at
318       your option, any later version of Perl 5 you may have available.
319
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321
322perl v5.32.1                      2021-01-27            File::Finder::Steps(3)
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