1File::Slurp(3)        User Contributed Perl Documentation       File::Slurp(3)
2
3
4

NAME

6       File::Slurp - Simple and Efficient Reading/Writing/Modifying of
7       Complete Files
8

SYNOPSIS

10         use File::Slurp;
11
12         # read in a whole file into a scalar
13         my $text = read_file('/path/file');
14
15         # read in a whole file into an array of lines
16         my @lines = read_file('/path/file');
17
18         # write out a whole file from a scalar
19         write_file('/path/file', $text);
20
21         # write out a whole file from an array of lines
22         write_file('/path/file', @lines);
23
24         # Here is a simple and fast way to load and save a simple config file
25         # made of key=value lines.
26         my %conf = read_file('/path/file') =~ /^(\w+)=(.*)$/mg;
27         write_file('/path/file', {atomic => 1}, map "$_=$conf{$_}\n", keys %conf);
28
29         # insert text at the beginning of a file
30         prepend_file('/path/file', $text);
31
32         # in-place edit to replace all 'foo' with 'bar' in file
33         edit_file { s/foo/bar/g } '/path/file';
34
35         # in-place edit to delete all lines with 'foo' from file
36         edit_file_lines sub { $_ = '' if /foo/ }, '/path/file';
37
38         # read in a whole directory of file names (skipping . and ..)
39         my @files = read_dir('/path/to/dir');
40

DESCRIPTION

42       This module provides subs that allow you to read or write entire files
43       with one simple call. They are designed to be simple to use, have
44       flexible ways to pass in or get the file contents and to be very
45       efficient. There is also a sub to read in all the files in a directory.
46
47   WARNING - PENDING DOOM
48       Although you technically can, do NOT use this module to work on file
49       handles, pipes, sockets, standard IO, or the "DATA" handle. These are
50       features implemented long ago that just really shouldn't be abused
51       here.
52
53       Be warned: this activity will lead to inaccurate encoding/decoding of
54       data.
55
56       All further mentions of actions on the above have been removed from
57       this documentation and that feature set will likely be deprecated in
58       the future.
59
60       In other words, if you don't have a filename to pass, consider using
61       the standard "do { local $/; <$fh> }", or
62       Data::Section/Data::Section::Simple for working with "__DATA__".
63

FUNCTIONS

65       File::Slurp implements the following functions.
66
67   append_file
68               use File::Slurp qw(append_file write_file);
69               my $res = append_file('/path/file', "Some text");
70               # same as
71               my $res = write_file('/path/file', {append => 1}, "Some text");
72
73       The "append_file" function is simply a synonym for the "write_file" in
74       File::Slurp function, but ensures that the "append" option is set.
75
76   edit_file
77               use File::Slurp qw(edit_file);
78               # perl -0777 -pi -e 's/foo/bar/g' /path/file
79               edit_file { s/foo/bar/g } '/path/file';
80               edit_file sub { s/foo/bar/g }, '/path/file';
81               sub replace_foo { s/foo/bar/g }
82               edit_file \&replace_foo, '/path/file';
83
84       The "edit_file" function reads in a file into $_, executes a code block
85       that should modify $_, and then writes $_ back to the file. The
86       "edit_file" function reads in the entire file and calls the code block
87       one time. It is equivalent to the "-pi" command line options of Perl
88       but you can call it from inside your program and not have to fork out a
89       process.
90
91       The first argument to "edit_file" is a code block or a code reference.
92       The code block is not followed by a comma (as with "grep" and "map")
93       but a code reference is followed by a comma.
94
95       The next argument is the filename.
96
97       The next argument(s) is either a hash reference or a flattened hash,
98       "key => value" pairs. The options are passed through to the
99       "write_file" in File::Slurp function. All options are described there.
100       Only the "binmode" and "err_mode" options are supported. The call to
101       "write_file" in File::Slurp has the "atomic" option set so you will
102       always have a consistent file.
103
104   edit_file_lines
105               use File::Slurp qw(edit_file_lines);
106               # perl -pi -e '$_ = "" if /foo/' /path/file
107               edit_file_lines { $_ = '' if /foo/ } '/path/file';
108               edit_file_lines sub { $_ = '' if /foo/ }, '/path/file';
109               sub delete_foo { $_ = '' if /foo/ }
110               edit_file \&delete_foo, '/path/file';
111
112       The "edit_file_lines" function reads each line of a file into $_, and
113       executes a code block that should modify $_. It will then write $_ back
114       to the file. It is equivalent to the "-pi" command line options of Perl
115       but you can call it from inside your program and not have to fork out a
116       process.
117
118       The first argument to "edit_file_lines" is a code block or a code
119       reference.  The code block is not followed by a comma (as with "grep"
120       and "map") but a code reference is followed by a comma.
121
122       The next argument is the filename.
123
124       The next argument(s) is either a hash reference or a flattened hash,
125       "key => value" pairs. The options are passed through to the
126       "write_file" in File::Slurp function. All options are described there.
127       Only the "binmode" and "err_mode" options are supported. The call to
128       "write_file" in File::Slurp has the "atomic" option set so you will
129       always have a consistent file.
130
131   ef
132               use File::Slurp qw(ef);
133               # perl -0777 -pi -e 's/foo/bar/g' /path/file
134               ef { s/foo/bar/g } '/path/file';
135               ef sub { s/foo/bar/g }, '/path/file';
136               sub replace_foo { s/foo/bar/g }
137               ef \&replace_foo, '/path/file';
138
139       The "ef" function is simply a synonym for the "edit_file" in
140       File::Slurp function.
141
142   efl
143               use File::Slurp qw(efl);
144               # perl -pi -e '$_ = "" if /foo/' /path/file
145               efl { $_ = '' if /foo/ } '/path/file';
146               efl sub { $_ = '' if /foo/ }, '/path/file';
147               sub delete_foo { $_ = '' if /foo/ }
148               efl \&delete_foo, '/path/file';
149
150       The "efl" function is simply a synonym for the "edit_file_lines" in
151       File::Slurp function.
152
153   overwrite_file
154               use File::Slurp qw(overwrite_file);
155               my $res = overwrite_file('/path/file', "Some text");
156
157       The "overwrite_file" function is simply a synonym for the "write_file"
158       in File::Slurp function.
159
160   prepend_file
161               use File::Slurp qw(prepend_file);
162               prepend_file('/path/file', $header);
163               prepend_file('/path/file', \@lines);
164               prepend_file('/path/file', { binmode => ':raw'}, $bin_data);
165
166               # equivalent to:
167               use File::Slurp qw(read_file write_file);
168               my $content = read_file('/path/file');
169               my $new_content = "hahahaha";
170               write_file('/path/file', $new_content . $content);
171
172       The "prepend_file" function is the opposite of "append_file" in
173       File::Slurp as it writes new contents to the beginning of the file
174       instead of the end. It is a combination of "read_file" in File::Slurp
175       and "write_file" in File::Slurp. It works by first using "read_file" to
176       slurp in the file and then calling "write_file" with the new data and
177       the existing file data.
178
179       The first argument to "prepend_file" is the filename.
180
181       The next argument(s) is either a hash reference or a flattened hash,
182       "key => value" pairs. The options are passed through to the
183       "write_file" in File::Slurp function. All options are described there.
184
185       Only the "binmode" and "err_mode" options are supported. The
186       "write_file" call has the "atomic" option set so you will always have a
187       consistent file.
188
189   read_dir
190               use File::Slurp qw(read_dir);
191               my @files = read_dir('/path/to/dir');
192               # all files, even the dots
193               my @files = read_dir('/path/to/dir', keep_dot_dot => 1);
194               # keep the full file path
195               my @paths = read_dir('/path/to/dir', prefix => 1);
196               # scalar context
197               my $files_ref = read_dir('/path/to/dir');
198
199       This function returns a list of the filenames in the supplied
200       directory. In list context, an array is returned, in scalar context, an
201       array reference is returned.
202
203       The first argument is the path to the directory to read.
204
205       The next argument(s) is either a hash reference or a flattened hash,
206       "key => value" pairs. The following options are available:
207
208       •   err_mode
209
210           The "err_mode" option has three possible values: "quiet", "carp",
211           or the default, "croak". In "quiet" mode, all errors will be
212           silent. In "carp" mode, all errors will be emitted as warnings.
213           And, in "croak" mode, all errors will be emitted as exceptions.
214           Take a look at Try::Tiny or Syntax::Keyword::Try to see how to
215           catch exceptions.
216
217       •   keep_dot_dot
218
219           The "keep_dot_dot" option is a boolean option, defaulted to false
220           (0).  Setting this option to true (1) will also return the "." and
221           ".." files that are removed from the file list by default.
222
223       •   prefix
224
225           The "prefix" option is a boolean option, defaulted to false (0).
226           Setting this option to true (1) add the directory as a prefix to
227           the file.  The directory and the filename are joined using
228           "File::Spec->catfile()" to ensure the proper directory separator is
229           used for your OS. See File::Spec.
230
231   read_file
232               use File::Slurp qw(read_file);
233               my $text = read_file('/path/file');
234               my $bin = read_file('/path/file', { binmode => ':raw' });
235               my @lines = read_file('/path/file');
236               my $lines_ref = read_file('/path/file', array_ref => 1);
237               my $lines_ref = [ read_file('/path/file') ];
238
239               # or we can read into a buffer:
240               my $buffer;
241               read_file('/path/file', buf_ref => \$buffer);
242
243               # or we can set the block size for the read
244               my $text_ref = read_file('/path/file', blk_size => 10_000_000, array_ref => 1);
245
246               # or we can get a scalar reference
247               my $text_ref = read_file('/path/file', scalar_ref => 1);
248
249       This function reads in an entire file and returns its contents to the
250       caller. In scalar context it returns the entire file as a single
251       scalar. In list context it will return a list of lines (using the
252       current value of $/ as the separator, including support for paragraph
253       mode when it is set to '').
254
255       The first argument is the path to the file to be slurped in.
256
257       The next argument(s) is either a hash reference or a flattened hash,
258       "key => value" pairs. The following options are available:
259
260       •   array_ref
261
262           The "array_ref" option is a boolean option, defaulted to false (0).
263           Setting this option to true (1) will only have relevance if the
264           "read_file" function is called in scalar context. When true, the
265           "read_file" function will return a reference to an array of the
266           lines in the file.
267
268       •   binmode
269
270           The "binmode" option is a string option, defaulted to empty ('').
271           If you set the "binmode" option, then its value is passed to a call
272           to "binmode" on the opened handle. You can use this to set the file
273           to be read in binary mode, utf8, etc. See "perldoc -f binmode" for
274           more.
275
276       •   blk_size
277
278           You can use this option to set the block size used when slurping
279           from an already open handle (like "\*STDIN"). It defaults to 1MB.
280
281       •   buf_ref
282
283           The "buf_ref" option can be used in conjunction with any of the
284           other options.  You can use this option to pass in a scalar
285           reference and the slurped file contents will be stored in the
286           scalar. This saves an extra copy of the slurped file and can lower
287           RAM usage vs returning the file. It is usually the fastest way to
288           read a file into a scalar.
289
290       •   chomp
291
292           The "chomp" option is a boolean option, defaulted to false (0).
293           Setting this option to true (1) will cause each line to have its
294           contents "chomp"ed.  This option works in list context or in scalar
295           context with the "array_ref" option.
296
297       •   err_mode
298
299           The "err_mode" option has three possible values: "quiet", "carp",
300           or the default, "croak". In "quiet" mode, all errors will be
301           silent. In "carp" mode, all errors will be emitted as warnings.
302           And, in "croak" mode, all errors will be emitted as exceptions.
303           Take a look at Try::Tiny or Syntax::Keyword::Try to see how to
304           catch exceptions.
305
306       •   scalar_ref
307
308           The "scalar_ref" option is a boolean option, defaulted to false
309           (0). It only has meaning in scalar context. The return value will
310           be a scalar reference to a string which is the contents of the
311           slurped file. This will usually be faster than returning the plain
312           scalar. It will also save memory as it will not make a copy of the
313           file to return.
314
315   rf
316               use File::Slurp qw(rf);
317               my $text = rf('/path/file');
318
319       The "rf" function is simply a synonym for the "read_file" in
320       File::Slurp function.
321
322   slurp
323               use File::Slurp qw(slurp);
324               my $text = slurp('/path/file');
325
326       The "slurp" function is simply a synonym for the "read_file" in
327       File::Slurp function.
328
329   wf
330               use File::Slurp qw(wf);
331               my $res = wf('/path/file', "Some text");
332
333       The "wf" function is simply a synonym for the "write_file" in
334       File::Slurp function.
335
336   write_file
337               use File::Slurp qw(write_file);
338               write_file('/path/file', @data);
339               write_file('/path/file', {append => 1}, @data);
340               write_file('/path/file', {binmode => ':raw'}, $buffer);
341               write_file('/path/file', \$buffer);
342               write_file('/path/file', $buffer);
343               write_file('/path/file', \@lines);
344               write_file('/path/file', @lines);
345
346               # binmode
347               write_file('/path/file', {binmode => ':raw'}, @data);
348               write_file('/path/file', {binmode => ':utf8'}, $utf_text);
349
350               # buffered
351               write_file('/path/file', {buf_ref => \$buffer});
352               write_file('/path/file', \$buffer);
353               write_file('/path/file', $buffer);
354
355               # append
356               write_file('/path/file', {append => 1}, @data);
357
358               # no clobbering
359               write_file('/path/file', {no_clobber => 1}, @data);
360
361       This function writes out an entire file in one call. By default
362       "write_file" returns 1 upon successfully writing the file or "undef" if
363       it encountered an error. You can change how errors are handled with the
364       "err_mode" option.
365
366       The first argument to "write_file" is the filename.
367
368       The next argument(s) is either a hash reference or a flattened hash,
369       "key => value" pairs. The following options are available:
370
371       •   append
372
373           The "append" option is a boolean option, defaulted to false (0).
374           Setting this option to true (1) will cause the data to be be
375           written at the end of the current file. Internally this sets the
376           "sysopen" mode flag "O_APPEND".
377
378           The "append_file" in File::Slurp function sets this option by
379           default.
380
381       •   atomic
382
383           The "atomic" option is a boolean option, defaulted to false (0).
384           Setting this option to true (1) will cause the file to be be
385           written to in an atomic fashion. A temporary file name is created
386           using "tempfile" in File::Temp.  After the file is closed it is
387           renamed to the original file name (and "rename" is an atomic
388           operation on most OSes). If the program using this were to crash in
389           the middle of this, then the temporary file could be left behind.
390
391       •   binmode
392
393           The "binmode" option is a string option, defaulted to empty ('').
394           If you set the "binmode" option, then its value is passed to a call
395           to "binmode" on the opened handle. You can use this to set the file
396           to be read in binary mode, utf8, etc. See "perldoc -f binmode" for
397           more.
398
399       •   buf_ref
400
401           The "buf_ref" option is used to pass in a scalar reference which
402           has the data to be written. If this is set then any data arguments
403           (including the scalar reference shortcut) in @_ will be ignored.
404
405       •   err_mode
406
407           The "err_mode" option has three possible values: "quiet", "carp",
408           or the default, "croak". In "quiet" mode, all errors will be
409           silent. In "carp" mode, all errors will be emitted as warnings.
410           And, in "croak" mode, all errors will be emitted as exceptions.
411           Take a look at Try::Tiny or Syntax::Keyword::Try to see how to
412           catch exceptions.
413
414       •   no_clobber
415
416           The "no_clobber" option is a boolean option, defaulted to false
417           (0). Setting this option to true (1) will ensure an that existing
418           file will not be overwritten.
419
420       •   perms
421
422           The "perms" option sets the permissions of newly-created files.
423           This value is modified by your process's "umask" and defaults to
424           0666 (same as "sysopen").
425
426           NOTE: this option is new as of File::Slurp version 9999.14.
427

EXPORT

429       These are exported by default or with
430
431               use File::Slurp qw(:std);
432               # read_file write_file overwrite_file append_file read_dir
433
434       These are exported with
435
436               use File::Slurp qw(:edit);
437               # edit_file edit_file_lines
438
439       You can get all subs in the module exported with
440
441               use File::Slurp qw(:all);
442

SEE ALSO

444       •   File::Slurper - Provides a straightforward set of functions for the
445           most common tasks of reading/writing text and binary files.
446
447       •   Path::Tiny - Lightweight and comprehensive file handling, including
448           simple methods for reading, writing, and editing text and binary
449           files.
450
451       •   Mojo::File - Similar to Path::Tiny for the Mojo toolkit, always
452           works in bytes.
453

AUTHOR

455       Uri Guttman, <uri@stemsystems.com>
456
458       Copyright (c) 2003 Uri Guttman. All rights reserved.
459
460       This program is free software; you can redistribute it and/or modify it
461       under the same terms as Perl itself.
462
463
464
465perl v5.34.0                      2021-07-22                    File::Slurp(3)
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