1File::Temp(3)         User Contributed Perl Documentation        File::Temp(3)
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3
4

NAME

6       File::Temp - return name and handle of a temporary file safely
7

VERSION

9       version 0.2311
10

SYNOPSIS

12         use File::Temp qw/ tempfile tempdir /;
13
14         $fh = tempfile();
15         ($fh, $filename) = tempfile();
16
17         ($fh, $filename) = tempfile( $template, DIR => $dir);
18         ($fh, $filename) = tempfile( $template, SUFFIX => '.dat');
19         ($fh, $filename) = tempfile( $template, TMPDIR => 1 );
20
21         binmode( $fh, ":utf8" );
22
23         $dir = tempdir( CLEANUP => 1 );
24         ($fh, $filename) = tempfile( DIR => $dir );
25
26       Object interface:
27
28         require File::Temp;
29         use File::Temp ();
30         use File::Temp qw/ :seekable /;
31
32         $fh = File::Temp->new();
33         $fname = $fh->filename;
34
35         $fh = File::Temp->new(TEMPLATE => $template);
36         $fname = $fh->filename;
37
38         $tmp = File::Temp->new( UNLINK => 0, SUFFIX => '.dat' );
39         print $tmp "Some data\n";
40         print "Filename is $tmp\n";
41         $tmp->seek( 0, SEEK_END );
42
43         $dir = File::Temp->newdir(); # CLEANUP => 1 by default
44
45       The following interfaces are provided for compatibility with existing
46       APIs. They should not be used in new code.
47
48       MkTemp family:
49
50         use File::Temp qw/ :mktemp  /;
51
52         ($fh, $file) = mkstemp( "tmpfileXXXXX" );
53         ($fh, $file) = mkstemps( "tmpfileXXXXXX", $suffix);
54
55         $tmpdir = mkdtemp( $template );
56
57         $unopened_file = mktemp( $template );
58
59       POSIX functions:
60
61         use File::Temp qw/ :POSIX /;
62
63         $file = tmpnam();
64         $fh = tmpfile();
65
66         ($fh, $file) = tmpnam();
67
68       Compatibility functions:
69
70         $unopened_file = File::Temp::tempnam( $dir, $pfx );
71

DESCRIPTION

73       "File::Temp" can be used to create and open temporary files in a safe
74       way.  There is both a function interface and an object-oriented
75       interface.  The File::Temp constructor or the tempfile() function can
76       be used to return the name and the open filehandle of a temporary file.
77       The tempdir() function can be used to create a temporary directory.
78
79       The security aspect of temporary file creation is emphasized such that
80       a filehandle and filename are returned together.  This helps guarantee
81       that a race condition can not occur where the temporary file is created
82       by another process between checking for the existence of the file and
83       its opening.  Additional security levels are provided to check, for
84       example, that the sticky bit is set on world writable directories.  See
85       "safe_level" for more information.
86
87       For compatibility with popular C library functions, Perl
88       implementations of the mkstemp() family of functions are provided.
89       These are, mkstemp(), mkstemps(), mkdtemp() and mktemp().
90
91       Additionally, implementations of the standard POSIX tmpnam() and
92       tmpfile() functions are provided if required.
93
94       Implementations of mktemp(), tmpnam(), and tempnam() are provided, but
95       should be used with caution since they return only a filename that was
96       valid when function was called, so cannot guarantee that the file will
97       not exist by the time the caller opens the filename.
98
99       Filehandles returned by these functions support the seekable methods.
100

OBJECT-ORIENTED INTERFACE

102       This is the primary interface for interacting with "File::Temp". Using
103       the OO interface a temporary file can be created when the object is
104       constructed and the file can be removed when the object is no longer
105       required.
106
107       Note that there is no method to obtain the filehandle from the
108       "File::Temp" object. The object itself acts as a filehandle.  The
109       object isa "IO::Handle" and isa "IO::Seekable" so all those methods are
110       available.
111
112       Also, the object is configured such that it stringifies to the name of
113       the temporary file and so can be compared to a filename directly.  It
114       numifies to the "refaddr" the same as other handles and so can be
115       compared to other handles with "==".
116
117           $fh eq $filename       # as a string
118           $fh != \*STDOUT        # as a number
119
120       Available since 0.14.
121
122       new Create a temporary file object.
123
124             my $tmp = File::Temp->new();
125
126           by default the object is constructed as if "tempfile" was called
127           without options, but with the additional behaviour that the
128           temporary file is removed by the object destructor if UNLINK is set
129           to true (the default).
130
131           Supported arguments are the same as for "tempfile": UNLINK
132           (defaulting to true), DIR, EXLOCK, PERMS and SUFFIX.  Additionally,
133           the filename template is specified using the TEMPLATE option. The
134           OPEN option is not supported (the file is always opened).
135
136            $tmp = File::Temp->new( TEMPLATE => 'tempXXXXX',
137                                   DIR => 'mydir',
138                                   SUFFIX => '.dat');
139
140           Arguments are case insensitive.
141
142           Can call croak() if an error occurs.
143
144           Available since 0.14.
145
146           TEMPLATE available since 0.23
147
148       newdir
149           Create a temporary directory using an object oriented interface.
150
151             $dir = File::Temp->newdir();
152
153           By default the directory is deleted when the object goes out of
154           scope.
155
156           Supports the same options as the "tempdir" function. Note that
157           directories created with this method default to CLEANUP => 1.
158
159             $dir = File::Temp->newdir( $template, %options );
160
161           A template may be specified either with a leading template or with
162           a TEMPLATE argument.
163
164           Available since 0.19.
165
166           TEMPLATE available since 0.23.
167
168       filename
169           Return the name of the temporary file associated with this object
170           (if the object was created using the "new" constructor).
171
172             $filename = $tmp->filename;
173
174           This method is called automatically when the object is used as a
175           string.
176
177           Current API available since 0.14
178
179       dirname
180           Return the name of the temporary directory associated with this
181           object (if the object was created using the "newdir" constructor).
182
183             $dirname = $tmpdir->dirname;
184
185           This method is called automatically when the object is used in
186           string context.
187
188       unlink_on_destroy
189           Control whether the file is unlinked when the object goes out of
190           scope.  The file is removed if this value is true and $KEEP_ALL is
191           not.
192
193            $fh->unlink_on_destroy( 1 );
194
195           Default is for the file to be removed.
196
197           Current API available since 0.15
198
199       DESTROY
200           When the object goes out of scope, the destructor is called. This
201           destructor will attempt to unlink the file (using unlink1) if the
202           constructor was called with UNLINK set to 1 (the default state if
203           UNLINK is not specified).
204
205           No error is given if the unlink fails.
206
207           If the object has been passed to a child process during a fork, the
208           file will be deleted when the object goes out of scope in the
209           parent.
210
211           For a temporary directory object the directory will be removed
212           unless the CLEANUP argument was used in the constructor (and set to
213           false) or "unlink_on_destroy" was modified after creation.  Note
214           that if a temp directory is your current directory, it cannot be
215           removed - a warning will be given in this case.  "chdir()" out of
216           the directory before letting the object go out of scope.
217
218           If the global variable $KEEP_ALL is true, the file or directory
219           will not be removed.
220

FUNCTIONS

222       This section describes the recommended interface for generating
223       temporary files and directories.
224
225       tempfile
226           This is the basic function to generate temporary files.  The
227           behaviour of the file can be changed using various options:
228
229             $fh = tempfile();
230             ($fh, $filename) = tempfile();
231
232           Create a temporary file in  the directory specified for temporary
233           files, as specified by the tmpdir() function in File::Spec.
234
235             ($fh, $filename) = tempfile($template);
236
237           Create a temporary file in the current directory using the supplied
238           template.  Trailing `X' characters are replaced with random letters
239           to generate the filename.  At least four `X' characters must be
240           present at the end of the template.
241
242             ($fh, $filename) = tempfile($template, SUFFIX => $suffix)
243
244           Same as previously, except that a suffix is added to the template
245           after the `X' translation.  Useful for ensuring that a temporary
246           filename has a particular extension when needed by other
247           applications.  But see the WARNING at the end.
248
249             ($fh, $filename) = tempfile($template, DIR => $dir);
250
251           Translates the template as before except that a directory name is
252           specified.
253
254             ($fh, $filename) = tempfile($template, TMPDIR => 1);
255
256           Equivalent to specifying a DIR of "File::Spec->tmpdir", writing the
257           file into the same temporary directory as would be used if no
258           template was specified at all.
259
260             ($fh, $filename) = tempfile($template, UNLINK => 1);
261
262           Return the filename and filehandle as before except that the file
263           is automatically removed when the program exits (dependent on
264           $KEEP_ALL). Default is for the file to be removed if a file handle
265           is requested and to be kept if the filename is requested. In a
266           scalar context (where no filename is returned) the file is always
267           deleted either (depending on the operating system) on exit or when
268           it is closed (unless $KEEP_ALL is true when the temp file is
269           created).
270
271           Use the object-oriented interface if fine-grained control of when a
272           file is removed is required.
273
274           If the template is not specified, a template is always
275           automatically generated. This temporary file is placed in tmpdir()
276           (File::Spec) unless a directory is specified explicitly with the
277           DIR option.
278
279             $fh = tempfile( DIR => $dir );
280
281           If called in scalar context, only the filehandle is returned and
282           the file will automatically be deleted when closed on operating
283           systems that support this (see the description of tmpfile()
284           elsewhere in this document).  This is the preferred mode of
285           operation, as if you only have a filehandle, you can never create a
286           race condition by fumbling with the filename. On systems that can
287           not unlink an open file or can not mark a file as temporary when it
288           is opened (for example, Windows NT uses the "O_TEMPORARY" flag) the
289           file is marked for deletion when the program ends (equivalent to
290           setting UNLINK to 1). The "UNLINK" flag is ignored if present.
291
292             (undef, $filename) = tempfile($template, OPEN => 0);
293
294           This will return the filename based on the template but will not
295           open this file.  Cannot be used in conjunction with UNLINK set to
296           true. Default is to always open the file to protect from possible
297           race conditions. A warning is issued if warnings are turned on.
298           Consider using the tmpnam() and mktemp() functions described
299           elsewhere in this document if opening the file is not required.
300
301           To open the temporary filehandle with O_EXLOCK (open with exclusive
302           file lock) use "EXLOCK=>1". This is supported only by some
303           operating systems (most notably BSD derived systems). By default
304           EXLOCK will be false. Former "File::Temp" versions set EXLOCK to
305           true, so to be sure to get an unlocked filehandle also with older
306           versions, explicitly set "EXLOCK=>0".
307
308             ($fh, $filename) = tempfile($template, EXLOCK => 1);
309
310           By default, the temp file is created with 0600 file permissions.
311           Use "PERMS" to change this:
312
313             ($fh, $filename) = tempfile($template, PERMS => 0666);
314
315           Options can be combined as required.
316
317           Will croak() if there is an error.
318
319           Available since 0.05.
320
321           UNLINK flag available since 0.10.
322
323           TMPDIR flag available since 0.19.
324
325           EXLOCK flag available since 0.19.
326
327           PERMS flag available since 0.2310.
328
329       tempdir
330           This is the recommended interface for creation of temporary
331           directories.  By default the directory will not be removed on exit
332           (that is, it won't be temporary; this behaviour can not be changed
333           because of issues with backwards compatibility). To enable removal
334           either use the CLEANUP option which will trigger removal on program
335           exit, or consider using the "newdir" method in the object interface
336           which will allow the directory to be cleaned up when the object
337           goes out of scope.
338
339           The behaviour of the function depends on the arguments:
340
341             $tempdir = tempdir();
342
343           Create a directory in tmpdir() (see File::Spec).
344
345             $tempdir = tempdir( $template );
346
347           Create a directory from the supplied template. This template is
348           similar to that described for tempfile(). `X' characters at the end
349           of the template are replaced with random letters to construct the
350           directory name. At least four `X' characters must be in the
351           template.
352
353             $tempdir = tempdir ( DIR => $dir );
354
355           Specifies the directory to use for the temporary directory.  The
356           temporary directory name is derived from an internal template.
357
358             $tempdir = tempdir ( $template, DIR => $dir );
359
360           Prepend the supplied directory name to the template. The template
361           should not include parent directory specifications itself. Any
362           parent directory specifications are removed from the template
363           before prepending the supplied directory.
364
365             $tempdir = tempdir ( $template, TMPDIR => 1 );
366
367           Using the supplied template, create the temporary directory in a
368           standard location for temporary files. Equivalent to doing
369
370             $tempdir = tempdir ( $template, DIR => File::Spec->tmpdir);
371
372           but shorter. Parent directory specifications are stripped from the
373           template itself. The "TMPDIR" option is ignored if "DIR" is set
374           explicitly.  Additionally, "TMPDIR" is implied if neither a
375           template nor a directory are supplied.
376
377             $tempdir = tempdir( $template, CLEANUP => 1);
378
379           Create a temporary directory using the supplied template, but
380           attempt to remove it (and all files inside it) when the program
381           exits. Note that an attempt will be made to remove all files from
382           the directory even if they were not created by this module
383           (otherwise why ask to clean it up?). The directory removal is made
384           with the rmtree() function from the File::Path module.  Of course,
385           if the template is not specified, the temporary directory will be
386           created in tmpdir() and will also be removed at program exit.
387
388           Will croak() if there is an error.
389
390           Current API available since 0.05.
391

MKTEMP FUNCTIONS

393       The following functions are Perl implementations of the mktemp() family
394       of temp file generation system calls.
395
396       mkstemp
397           Given a template, returns a filehandle to the temporary file and
398           the name of the file.
399
400             ($fh, $name) = mkstemp( $template );
401
402           In scalar context, just the filehandle is returned.
403
404           The template may be any filename with some number of X's appended
405           to it, for example /tmp/temp.XXXX. The trailing X's are replaced
406           with unique alphanumeric combinations.
407
408           Will croak() if there is an error.
409
410           Current API available since 0.05.
411
412       mkstemps
413           Similar to mkstemp(), except that an extra argument can be supplied
414           with a suffix to be appended to the template.
415
416             ($fh, $name) = mkstemps( $template, $suffix );
417
418           For example a template of "testXXXXXX" and suffix of ".dat" would
419           generate a file similar to testhGji_w.dat.
420
421           Returns just the filehandle alone when called in scalar context.
422
423           Will croak() if there is an error.
424
425           Current API available since 0.05.
426
427       mkdtemp
428           Create a directory from a template. The template must end in X's
429           that are replaced by the routine.
430
431             $tmpdir_name = mkdtemp($template);
432
433           Returns the name of the temporary directory created.
434
435           Directory must be removed by the caller.
436
437           Will croak() if there is an error.
438
439           Current API available since 0.05.
440
441       mktemp
442           Returns a valid temporary filename but does not guarantee that the
443           file will not be opened by someone else.
444
445             $unopened_file = mktemp($template);
446
447           Template is the same as that required by mkstemp().
448
449           Will croak() if there is an error.
450
451           Current API available since 0.05.
452

POSIX FUNCTIONS

454       This section describes the re-implementation of the tmpnam() and
455       tmpfile() functions described in POSIX using the mkstemp() from this
456       module.
457
458       Unlike the POSIX implementations, the directory used for the temporary
459       file is not specified in a system include file ("P_tmpdir") but simply
460       depends on the choice of tmpdir() returned by File::Spec. On some
461       implementations this location can be set using the "TMPDIR" environment
462       variable, which may not be secure.  If this is a problem, simply use
463       mkstemp() and specify a template.
464
465       tmpnam
466           When called in scalar context, returns the full name (including
467           path) of a temporary file (uses mktemp()). The only check is that
468           the file does not already exist, but there is no guarantee that
469           that condition will continue to apply.
470
471             $file = tmpnam();
472
473           When called in list context, a filehandle to the open file and a
474           filename are returned. This is achieved by calling mkstemp() after
475           constructing a suitable template.
476
477             ($fh, $file) = tmpnam();
478
479           If possible, this form should be used to prevent possible race
480           conditions.
481
482           See "tmpdir" in File::Spec for information on the choice of
483           temporary directory for a particular operating system.
484
485           Will croak() if there is an error.
486
487           Current API available since 0.05.
488
489       tmpfile
490           Returns the filehandle of a temporary file.
491
492             $fh = tmpfile();
493
494           The file is removed when the filehandle is closed or when the
495           program exits. No access to the filename is provided.
496
497           If the temporary file can not be created undef is returned.
498           Currently this command will probably not work when the temporary
499           directory is on an NFS file system.
500
501           Will croak() if there is an error.
502
503           Available since 0.05.
504
505           Returning undef if unable to create file added in 0.12.
506

ADDITIONAL FUNCTIONS

508       These functions are provided for backwards compatibility with common
509       tempfile generation C library functions.
510
511       They are not exported and must be addressed using the full package
512       name.
513
514       tempnam
515           Return the name of a temporary file in the specified directory
516           using a prefix. The file is guaranteed not to exist at the time the
517           function was called, but such guarantees are good for one clock
518           tick only.  Always use the proper form of "sysopen" with "O_CREAT |
519           O_EXCL" if you must open such a filename.
520
521             $filename = File::Temp::tempnam( $dir, $prefix );
522
523           Equivalent to running mktemp() with $dir/$prefixXXXXXXXX (using
524           unix file convention as an example)
525
526           Because this function uses mktemp(), it can suffer from race
527           conditions.
528
529           Will croak() if there is an error.
530
531           Current API available since 0.05.
532

UTILITY FUNCTIONS

534       Useful functions for dealing with the filehandle and filename.
535
536       unlink0
537           Given an open filehandle and the associated filename, make a safe
538           unlink. This is achieved by first checking that the filename and
539           filehandle initially point to the same file and that the number of
540           links to the file is 1 (all fields returned by stat() are
541           compared).  Then the filename is unlinked and the filehandle
542           checked once again to verify that the number of links on that file
543           is now 0.  This is the closest you can come to making sure that the
544           filename unlinked was the same as the file whose descriptor you
545           hold.
546
547             unlink0($fh, $path)
548                or die "Error unlinking file $path safely";
549
550           Returns false on error but croaks() if there is a security anomaly.
551           The filehandle is not closed since on some occasions this is not
552           required.
553
554           On some platforms, for example Windows NT, it is not possible to
555           unlink an open file (the file must be closed first). On those
556           platforms, the actual unlinking is deferred until the program ends
557           and good status is returned. A check is still performed to make
558           sure that the filehandle and filename are pointing to the same
559           thing (but not at the time the end block is executed since the
560           deferred removal may not have access to the filehandle).
561
562           Additionally, on Windows NT not all the fields returned by stat()
563           can be compared. For example, the "dev" and "rdev" fields seem to
564           be different.  Also, it seems that the size of the file returned by
565           stat() does not always agree, with "stat(FH)" being more accurate
566           than "stat(filename)", presumably because of caching issues even
567           when using autoflush (this is usually overcome by waiting a while
568           after writing to the tempfile before attempting to "unlink0" it).
569
570           Finally, on NFS file systems the link count of the file handle does
571           not always go to zero immediately after unlinking. Currently, this
572           command is expected to fail on NFS disks.
573
574           This function is disabled if the global variable $KEEP_ALL is true
575           and an unlink on open file is supported. If the unlink is to be
576           deferred to the END block, the file is still registered for
577           removal.
578
579           This function should not be called if you are using the object
580           oriented interface since the it will interfere with the object
581           destructor deleting the file.
582
583           Available Since 0.05.
584
585           If can not unlink open file, defer removal until later available
586           since 0.06.
587
588       cmpstat
589           Compare "stat" of filehandle with "stat" of provided filename.
590           This can be used to check that the filename and filehandle
591           initially point to the same file and that the number of links to
592           the file is 1 (all fields returned by stat() are compared).
593
594             cmpstat($fh, $path)
595                or die "Error comparing handle with file";
596
597           Returns false if the stat information differs or if the link count
598           is greater than 1. Calls croak if there is a security anomaly.
599
600           On certain platforms, for example Windows, not all the fields
601           returned by stat() can be compared. For example, the "dev" and
602           "rdev" fields seem to be different in Windows.  Also, it seems that
603           the size of the file returned by stat() does not always agree, with
604           "stat(FH)" being more accurate than "stat(filename)", presumably
605           because of caching issues even when using autoflush (this is
606           usually overcome by waiting a while after writing to the tempfile
607           before attempting to "unlink0" it).
608
609           Not exported by default.
610
611           Current API available since 0.14.
612
613       unlink1
614           Similar to "unlink0" except after file comparison using cmpstat,
615           the filehandle is closed prior to attempting to unlink the file.
616           This allows the file to be removed without using an END block, but
617           does mean that the post-unlink comparison of the filehandle state
618           provided by "unlink0" is not available.
619
620             unlink1($fh, $path)
621                or die "Error closing and unlinking file";
622
623           Usually called from the object destructor when using the OO
624           interface.
625
626           Not exported by default.
627
628           This function is disabled if the global variable $KEEP_ALL is true.
629
630           Can call croak() if there is a security anomaly during the stat()
631           comparison.
632
633           Current API available since 0.14.
634
635       cleanup
636           Calling this function will cause any temp files or temp directories
637           that are registered for removal to be removed. This happens
638           automatically when the process exits but can be triggered manually
639           if the caller is sure that none of the temp files are required.
640           This method can be registered as an Apache callback.
641
642           Note that if a temp directory is your current directory, it cannot
643           be removed.  "chdir()" out of the directory first before calling
644           "cleanup()". (For the cleanup at program exit when the CLEANUP flag
645           is set, this happens automatically.)
646
647           On OSes where temp files are automatically removed when the temp
648           file is closed, calling this function will have no effect other
649           than to remove temporary directories (which may include temporary
650           files).
651
652             File::Temp::cleanup();
653
654           Not exported by default.
655
656           Current API available since 0.15.
657

PACKAGE VARIABLES

659       These functions control the global state of the package.
660
661       safe_level
662           Controls the lengths to which the module will go to check the
663           safety of the temporary file or directory before proceeding.
664           Options are:
665
666           STANDARD
667                   Do the basic security measures to ensure the directory
668                   exists and is writable, that temporary files are opened
669                   only if they do not already exist, and that possible race
670                   conditions are avoided.  Finally the unlink0 function is
671                   used to remove files safely.
672
673           MEDIUM  In addition to the STANDARD security, the output directory
674                   is checked to make sure that it is owned either by root or
675                   the user running the program. If the directory is writable
676                   by group or by other, it is then checked to make sure that
677                   the sticky bit is set.
678
679                   Will not work on platforms that do not support the "-k"
680                   test for sticky bit.
681
682           HIGH    In addition to the MEDIUM security checks, also check for
683                   the possibility of ``chown() giveaway'' using the POSIX
684                   sysconf() function. If this is a possibility, each
685                   directory in the path is checked in turn for safeness,
686                   recursively walking back to the root directory.
687
688                   For platforms that do not support the POSIX
689                   "_PC_CHOWN_RESTRICTED" symbol (for example, Windows NT) it
690                   is assumed that ``chown() giveaway'' is possible and the
691                   recursive test is performed.
692
693           The level can be changed as follows:
694
695             File::Temp->safe_level( File::Temp::HIGH );
696
697           The level constants are not exported by the module.
698
699           Currently, you must be running at least perl v5.6.0 in order to run
700           with MEDIUM or HIGH security. This is simply because the safety
701           tests use functions from Fcntl that are not available in older
702           versions of perl. The problem is that the version number for Fcntl
703           is the same in perl 5.6.0 and in 5.005_03 even though they are
704           different versions.
705
706           On systems that do not support the HIGH or MEDIUM safety levels
707           (for example Win NT or OS/2) any attempt to change the level will
708           be ignored. The decision to ignore rather than raise an exception
709           allows portable programs to be written with high security in mind
710           for the systems that can support this without those programs
711           failing on systems where the extra tests are irrelevant.
712
713           If you really need to see whether the change has been accepted
714           simply examine the return value of "safe_level".
715
716             $newlevel = File::Temp->safe_level( File::Temp::HIGH );
717             die "Could not change to high security"
718                 if $newlevel != File::Temp::HIGH;
719
720           Available since 0.05.
721
722       TopSystemUID
723           This is the highest UID on the current system that refers to a root
724           UID. This is used to make sure that the temporary directory is
725           owned by a system UID ("root", "bin", "sys" etc) rather than simply
726           by root.
727
728           This is required since on many unix systems "/tmp" is not owned by
729           root.
730
731           Default is to assume that any UID less than or equal to 10 is a
732           root UID.
733
734             File::Temp->top_system_uid(10);
735             my $topid = File::Temp->top_system_uid;
736
737           This value can be adjusted to reduce security checking if required.
738           The value is only relevant when "safe_level" is set to MEDIUM or
739           higher.
740
741           Available since 0.05.
742
743       $KEEP_ALL
744           Controls whether temporary files and directories should be retained
745           regardless of any instructions in the program to remove them
746           automatically.  This is useful for debugging but should not be used
747           in production code.
748
749             $File::Temp::KEEP_ALL = 1;
750
751           Default is for files to be removed as requested by the caller.
752
753           In some cases, files will only be retained if this variable is true
754           when the file is created. This means that you can not create a
755           temporary file, set this variable and expect the temp file to still
756           be around when the program exits.
757
758       $DEBUG
759           Controls whether debugging messages should be enabled.
760
761             $File::Temp::DEBUG = 1;
762
763           Default is for debugging mode to be disabled.
764
765           Available since 0.15.
766

WARNING

768       For maximum security, endeavour always to avoid ever looking at,
769       touching, or even imputing the existence of the filename.  You do not
770       know that that filename is connected to the same file as the handle you
771       have, and attempts to check this can only trigger more race conditions.
772       It's far more secure to use the filehandle alone and dispense with the
773       filename altogether.
774
775       If you need to pass the handle to something that expects a filename
776       then on a unix system you can use ""/dev/fd/" . fileno($fh)" for
777       arbitrary programs. Perl code that uses the 2-argument version of
778       "open" can be passed ""+<=&" . fileno($fh)". Otherwise you will need to
779       pass the filename. You will have to clear the close-on-exec bit on that
780       file descriptor before passing it to another process.
781
782           use Fcntl qw/F_SETFD F_GETFD/;
783           fcntl($tmpfh, F_SETFD, 0)
784               or die "Can't clear close-on-exec flag on temp fh: $!\n";
785
786   Temporary files and NFS
787       Some problems are associated with using temporary files that reside on
788       NFS file systems and it is recommended that a local filesystem is used
789       whenever possible. Some of the security tests will most probably fail
790       when the temp file is not local. Additionally, be aware that the
791       performance of I/O operations over NFS will not be as good as for a
792       local disk.
793
794   Forking
795       In some cases files created by File::Temp are removed from within an
796       END block. Since END blocks are triggered when a child process exits
797       (unless "POSIX::_exit()" is used by the child) File::Temp takes care to
798       only remove those temp files created by a particular process ID. This
799       means that a child will not attempt to remove temp files created by the
800       parent process.
801
802       If you are forking many processes in parallel that are all creating
803       temporary files, you may need to reset the random number seed using
804       srand(EXPR) in each child else all the children will attempt to walk
805       through the same set of random file names and may well cause themselves
806       to give up if they exceed the number of retry attempts.
807
808   Directory removal
809       Note that if you have chdir'ed into the temporary directory and it is
810       subsequently cleaned up (either in the END block or as part of object
811       destruction), then you will get a warning from File::Path::rmtree().
812
813   Taint mode
814       If you need to run code under taint mode, updating to the latest
815       File::Spec is highly recommended.  On Windows, if the directory given
816       by File::Spec::tmpdir isn't writable, File::Temp will attempt to
817       fallback to the user's local application data directory or croak with
818       an error.
819
820   BINMODE
821       The file returned by File::Temp will have been opened in binary mode if
822       such a mode is available. If that is not correct, use the "binmode()"
823       function to change the mode of the filehandle.
824
825       Note that you can modify the encoding of a file opened by File::Temp
826       also by using "binmode()".
827

HISTORY

829       Originally began life in May 1999 as an XS interface to the system
830       mkstemp() function. In March 2000, the OpenBSD mkstemp() code was
831       translated to Perl for total control of the code's security checking,
832       to ensure the presence of the function regardless of operating system
833       and to help with portability. The module was shipped as a standard part
834       of perl from v5.6.1.
835
836       Thanks to Tom Christiansen for suggesting that this module should be
837       written and providing ideas for code improvements and security
838       enhancements.
839

SEE ALSO

841       "tmpnam" in POSIX, "tmpfile" in POSIX, File::Spec, File::Path
842
843       See IO::File and File::MkTemp, Apache::TempFile for different
844       implementations of temporary file handling.
845
846       See File::Tempdir for an alternative object-oriented wrapper for the
847       "tempdir" function.
848

SUPPORT

850       Bugs may be submitted through the RT bug tracker
851       <https://rt.cpan.org/Public/Dist/Display.html?Name=File-Temp> (or
852       bug-File-Temp@rt.cpan.org <mailto:bug-File-Temp@rt.cpan.org>).
853
854       There is also a mailing list available for users of this distribution,
855       at <http://lists.perl.org/list/cpan-workers.html>.
856
857       There is also an irc channel available for users of this distribution,
858       at "#toolchain" on "irc.perl.org" <irc://irc.perl.org/#toolchain>.
859

AUTHOR

861       Tim Jenness <tjenness@cpan.org>
862

CONTRIBUTORS

864       •   Tim Jenness <t.jenness@jach.hawaii.edu>
865
866       •   Karen Etheridge <ether@cpan.org>
867
868       •   David Golden <dagolden@cpan.org>
869
870       •   Slaven Rezic <srezic@cpan.org>
871
872       •   mohawk2 <mohawk2@users.noreply.github.com>
873
874       •   Roy Ivy III <rivy.dev@gmail.com>
875
876       •   Peter Rabbitson <ribasushi@cpan.org>
877
878       •   Olivier Mengué <dolmen@cpan.org>
879
880       •   Peter John Acklam <pjacklam@online.no>
881
882       •   Tim Gim Yee <tim.gim.yee@gmail.com>
883
884       •   Nicolas R <atoomic@cpan.org>
885
886       •   Brian Mowrey <brian@drlabs.org>
887
888       •   Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
889
890       •   David Steinbrunner <dsteinbrunner@pobox.com>
891
892       •   Ed Avis <eda@linux01.wcl.local>
893
894       •   Guillem Jover <guillem@hadrons.org>
895
896       •   James E. Keenan <jkeen@verizon.net>
897
898       •   Kevin Ryde <user42@zip.com.au>
899
900       •   Ben Tilly <btilly@gmail.com>
901
903       This software is copyright (c) 2020 by Tim Jenness and the UK Particle
904       Physics and Astronomy Research Council.
905
906       This is free software; you can redistribute it and/or modify it under
907       the same terms as the Perl 5 programming language system itself.
908
909
910
911perl v5.36.0                      2022-07-22                     File::Temp(3)
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