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

NAME

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

VERSION

9       version 0.2309
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 and SUFFIX. Additionally, the
133           filename template is specified using the TEMPLATE option. The OPEN
134           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           Options can be combined as required.
311
312           Will croak() if there is an error.
313
314           Available since 0.05.
315
316           UNLINK flag available since 0.10.
317
318           TMPDIR flag available since 0.19.
319
320           EXLOCK flag available since 0.19.
321
322       tempdir
323           This is the recommended interface for creation of temporary
324           directories.  By default the directory will not be removed on exit
325           (that is, it won't be temporary; this behaviour can not be changed
326           because of issues with backwards compatibility). To enable removal
327           either use the CLEANUP option which will trigger removal on program
328           exit, or consider using the "newdir" method in the object interface
329           which will allow the directory to be cleaned up when the object
330           goes out of scope.
331
332           The behaviour of the function depends on the arguments:
333
334             $tempdir = tempdir();
335
336           Create a directory in tmpdir() (see File::Spec).
337
338             $tempdir = tempdir( $template );
339
340           Create a directory from the supplied template. This template is
341           similar to that described for tempfile(). `X' characters at the end
342           of the template are replaced with random letters to construct the
343           directory name. At least four `X' characters must be in the
344           template.
345
346             $tempdir = tempdir ( DIR => $dir );
347
348           Specifies the directory to use for the temporary directory.  The
349           temporary directory name is derived from an internal template.
350
351             $tempdir = tempdir ( $template, DIR => $dir );
352
353           Prepend the supplied directory name to the template. The template
354           should not include parent directory specifications itself. Any
355           parent directory specifications are removed from the template
356           before prepending the supplied directory.
357
358             $tempdir = tempdir ( $template, TMPDIR => 1 );
359
360           Using the supplied template, create the temporary directory in a
361           standard location for temporary files. Equivalent to doing
362
363             $tempdir = tempdir ( $template, DIR => File::Spec->tmpdir);
364
365           but shorter. Parent directory specifications are stripped from the
366           template itself. The "TMPDIR" option is ignored if "DIR" is set
367           explicitly.  Additionally, "TMPDIR" is implied if neither a
368           template nor a directory are supplied.
369
370             $tempdir = tempdir( $template, CLEANUP => 1);
371
372           Create a temporary directory using the supplied template, but
373           attempt to remove it (and all files inside it) when the program
374           exits. Note that an attempt will be made to remove all files from
375           the directory even if they were not created by this module
376           (otherwise why ask to clean it up?). The directory removal is made
377           with the rmtree() function from the File::Path module.  Of course,
378           if the template is not specified, the temporary directory will be
379           created in tmpdir() and will also be removed at program exit.
380
381           Will croak() if there is an error.
382
383           Current API available since 0.05.
384

MKTEMP FUNCTIONS

386       The following functions are Perl implementations of the mktemp() family
387       of temp file generation system calls.
388
389       mkstemp
390           Given a template, returns a filehandle to the temporary file and
391           the name of the file.
392
393             ($fh, $name) = mkstemp( $template );
394
395           In scalar context, just the filehandle is returned.
396
397           The template may be any filename with some number of X's appended
398           to it, for example /tmp/temp.XXXX. The trailing X's are replaced
399           with unique alphanumeric combinations.
400
401           Will croak() if there is an error.
402
403           Current API available since 0.05.
404
405       mkstemps
406           Similar to mkstemp(), except that an extra argument can be supplied
407           with a suffix to be appended to the template.
408
409             ($fh, $name) = mkstemps( $template, $suffix );
410
411           For example a template of "testXXXXXX" and suffix of ".dat" would
412           generate a file similar to testhGji_w.dat.
413
414           Returns just the filehandle alone when called in scalar context.
415
416           Will croak() if there is an error.
417
418           Current API available since 0.05.
419
420       mkdtemp
421           Create a directory from a template. The template must end in X's
422           that are replaced by the routine.
423
424             $tmpdir_name = mkdtemp($template);
425
426           Returns the name of the temporary directory created.
427
428           Directory must be removed by the caller.
429
430           Will croak() if there is an error.
431
432           Current API available since 0.05.
433
434       mktemp
435           Returns a valid temporary filename but does not guarantee that the
436           file will not be opened by someone else.
437
438             $unopened_file = mktemp($template);
439
440           Template is the same as that required by mkstemp().
441
442           Will croak() if there is an error.
443
444           Current API available since 0.05.
445

POSIX FUNCTIONS

447       This section describes the re-implementation of the tmpnam() and
448       tmpfile() functions described in POSIX using the mkstemp() from this
449       module.
450
451       Unlike the POSIX implementations, the directory used for the temporary
452       file is not specified in a system include file ("P_tmpdir") but simply
453       depends on the choice of tmpdir() returned by File::Spec. On some
454       implementations this location can be set using the "TMPDIR" environment
455       variable, which may not be secure.  If this is a problem, simply use
456       mkstemp() and specify a template.
457
458       tmpnam
459           When called in scalar context, returns the full name (including
460           path) of a temporary file (uses mktemp()). The only check is that
461           the file does not already exist, but there is no guarantee that
462           that condition will continue to apply.
463
464             $file = tmpnam();
465
466           When called in list context, a filehandle to the open file and a
467           filename are returned. This is achieved by calling mkstemp() after
468           constructing a suitable template.
469
470             ($fh, $file) = tmpnam();
471
472           If possible, this form should be used to prevent possible race
473           conditions.
474
475           See "tmpdir" in File::Spec for information on the choice of
476           temporary directory for a particular operating system.
477
478           Will croak() if there is an error.
479
480           Current API available since 0.05.
481
482       tmpfile
483           Returns the filehandle of a temporary file.
484
485             $fh = tmpfile();
486
487           The file is removed when the filehandle is closed or when the
488           program exits. No access to the filename is provided.
489
490           If the temporary file can not be created undef is returned.
491           Currently this command will probably not work when the temporary
492           directory is on an NFS file system.
493
494           Will croak() if there is an error.
495
496           Available since 0.05.
497
498           Returning undef if unable to create file added in 0.12.
499

ADDITIONAL FUNCTIONS

501       These functions are provided for backwards compatibility with common
502       tempfile generation C library functions.
503
504       They are not exported and must be addressed using the full package
505       name.
506
507       tempnam
508           Return the name of a temporary file in the specified directory
509           using a prefix. The file is guaranteed not to exist at the time the
510           function was called, but such guarantees are good for one clock
511           tick only.  Always use the proper form of "sysopen" with "O_CREAT |
512           O_EXCL" if you must open such a filename.
513
514             $filename = File::Temp::tempnam( $dir, $prefix );
515
516           Equivalent to running mktemp() with $dir/$prefixXXXXXXXX (using
517           unix file convention as an example)
518
519           Because this function uses mktemp(), it can suffer from race
520           conditions.
521
522           Will croak() if there is an error.
523
524           Current API available since 0.05.
525

UTILITY FUNCTIONS

527       Useful functions for dealing with the filehandle and filename.
528
529       unlink0
530           Given an open filehandle and the associated filename, make a safe
531           unlink. This is achieved by first checking that the filename and
532           filehandle initially point to the same file and that the number of
533           links to the file is 1 (all fields returned by stat() are
534           compared).  Then the filename is unlinked and the filehandle
535           checked once again to verify that the number of links on that file
536           is now 0.  This is the closest you can come to making sure that the
537           filename unlinked was the same as the file whose descriptor you
538           hold.
539
540             unlink0($fh, $path)
541                or die "Error unlinking file $path safely";
542
543           Returns false on error but croaks() if there is a security anomaly.
544           The filehandle is not closed since on some occasions this is not
545           required.
546
547           On some platforms, for example Windows NT, it is not possible to
548           unlink an open file (the file must be closed first). On those
549           platforms, the actual unlinking is deferred until the program ends
550           and good status is returned. A check is still performed to make
551           sure that the filehandle and filename are pointing to the same
552           thing (but not at the time the end block is executed since the
553           deferred removal may not have access to the filehandle).
554
555           Additionally, on Windows NT not all the fields returned by stat()
556           can be compared. For example, the "dev" and "rdev" fields seem to
557           be different.  Also, it seems that the size of the file returned by
558           stat() does not always agree, with "stat(FH)" being more accurate
559           than "stat(filename)", presumably because of caching issues even
560           when using autoflush (this is usually overcome by waiting a while
561           after writing to the tempfile before attempting to "unlink0" it).
562
563           Finally, on NFS file systems the link count of the file handle does
564           not always go to zero immediately after unlinking. Currently, this
565           command is expected to fail on NFS disks.
566
567           This function is disabled if the global variable $KEEP_ALL is true
568           and an unlink on open file is supported. If the unlink is to be
569           deferred to the END block, the file is still registered for
570           removal.
571
572           This function should not be called if you are using the object
573           oriented interface since the it will interfere with the object
574           destructor deleting the file.
575
576           Available Since 0.05.
577
578           If can not unlink open file, defer removal until later available
579           since 0.06.
580
581       cmpstat
582           Compare "stat" of filehandle with "stat" of provided filename.
583           This can be used to check that the filename and filehandle
584           initially point to the same file and that the number of links to
585           the file is 1 (all fields returned by stat() are compared).
586
587             cmpstat($fh, $path)
588                or die "Error comparing handle with file";
589
590           Returns false if the stat information differs or if the link count
591           is greater than 1. Calls croak if there is a security anomaly.
592
593           On certain platforms, for example Windows, not all the fields
594           returned by stat() can be compared. For example, the "dev" and
595           "rdev" fields seem to be different in Windows.  Also, it seems that
596           the size of the file returned by stat() does not always agree, with
597           "stat(FH)" being more accurate than "stat(filename)", presumably
598           because of caching issues even when using autoflush (this is
599           usually overcome by waiting a while after writing to the tempfile
600           before attempting to "unlink0" it).
601
602           Not exported by default.
603
604           Current API available since 0.14.
605
606       unlink1
607           Similar to "unlink0" except after file comparison using cmpstat,
608           the filehandle is closed prior to attempting to unlink the file.
609           This allows the file to be removed without using an END block, but
610           does mean that the post-unlink comparison of the filehandle state
611           provided by "unlink0" is not available.
612
613             unlink1($fh, $path)
614                or die "Error closing and unlinking file";
615
616           Usually called from the object destructor when using the OO
617           interface.
618
619           Not exported by default.
620
621           This function is disabled if the global variable $KEEP_ALL is true.
622
623           Can call croak() if there is a security anomaly during the stat()
624           comparison.
625
626           Current API available since 0.14.
627
628       cleanup
629           Calling this function will cause any temp files or temp directories
630           that are registered for removal to be removed. This happens
631           automatically when the process exits but can be triggered manually
632           if the caller is sure that none of the temp files are required.
633           This method can be registered as an Apache callback.
634
635           Note that if a temp directory is your current directory, it cannot
636           be removed.  "chdir()" out of the directory first before calling
637           "cleanup()". (For the cleanup at program exit when the CLEANUP flag
638           is set, this happens automatically.)
639
640           On OSes where temp files are automatically removed when the temp
641           file is closed, calling this function will have no effect other
642           than to remove temporary directories (which may include temporary
643           files).
644
645             File::Temp::cleanup();
646
647           Not exported by default.
648
649           Current API available since 0.15.
650

PACKAGE VARIABLES

652       These functions control the global state of the package.
653
654       safe_level
655           Controls the lengths to which the module will go to check the
656           safety of the temporary file or directory before proceeding.
657           Options are:
658
659           STANDARD
660                   Do the basic security measures to ensure the directory
661                   exists and is writable, that temporary files are opened
662                   only if they do not already exist, and that possible race
663                   conditions are avoided.  Finally the unlink0 function is
664                   used to remove files safely.
665
666           MEDIUM  In addition to the STANDARD security, the output directory
667                   is checked to make sure that it is owned either by root or
668                   the user running the program. If the directory is writable
669                   by group or by other, it is then checked to make sure that
670                   the sticky bit is set.
671
672                   Will not work on platforms that do not support the "-k"
673                   test for sticky bit.
674
675           HIGH    In addition to the MEDIUM security checks, also check for
676                   the possibility of ``chown() giveaway'' using the POSIX
677                   sysconf() function. If this is a possibility, each
678                   directory in the path is checked in turn for safeness,
679                   recursively walking back to the root directory.
680
681                   For platforms that do not support the POSIX
682                   "_PC_CHOWN_RESTRICTED" symbol (for example, Windows NT) it
683                   is assumed that ``chown() giveaway'' is possible and the
684                   recursive test is performed.
685
686           The level can be changed as follows:
687
688             File::Temp->safe_level( File::Temp::HIGH );
689
690           The level constants are not exported by the module.
691
692           Currently, you must be running at least perl v5.6.0 in order to run
693           with MEDIUM or HIGH security. This is simply because the safety
694           tests use functions from Fcntl that are not available in older
695           versions of perl. The problem is that the version number for Fcntl
696           is the same in perl 5.6.0 and in 5.005_03 even though they are
697           different versions.
698
699           On systems that do not support the HIGH or MEDIUM safety levels
700           (for example Win NT or OS/2) any attempt to change the level will
701           be ignored. The decision to ignore rather than raise an exception
702           allows portable programs to be written with high security in mind
703           for the systems that can support this without those programs
704           failing on systems where the extra tests are irrelevant.
705
706           If you really need to see whether the change has been accepted
707           simply examine the return value of "safe_level".
708
709             $newlevel = File::Temp->safe_level( File::Temp::HIGH );
710             die "Could not change to high security"
711                 if $newlevel != File::Temp::HIGH;
712
713           Available since 0.05.
714
715       TopSystemUID
716           This is the highest UID on the current system that refers to a root
717           UID. This is used to make sure that the temporary directory is
718           owned by a system UID ("root", "bin", "sys" etc) rather than simply
719           by root.
720
721           This is required since on many unix systems "/tmp" is not owned by
722           root.
723
724           Default is to assume that any UID less than or equal to 10 is a
725           root UID.
726
727             File::Temp->top_system_uid(10);
728             my $topid = File::Temp->top_system_uid;
729
730           This value can be adjusted to reduce security checking if required.
731           The value is only relevant when "safe_level" is set to MEDIUM or
732           higher.
733
734           Available since 0.05.
735
736       $KEEP_ALL
737           Controls whether temporary files and directories should be retained
738           regardless of any instructions in the program to remove them
739           automatically.  This is useful for debugging but should not be used
740           in production code.
741
742             $File::Temp::KEEP_ALL = 1;
743
744           Default is for files to be removed as requested by the caller.
745
746           In some cases, files will only be retained if this variable is true
747           when the file is created. This means that you can not create a
748           temporary file, set this variable and expect the temp file to still
749           be around when the program exits.
750
751       $DEBUG
752           Controls whether debugging messages should be enabled.
753
754             $File::Temp::DEBUG = 1;
755
756           Default is for debugging mode to be disabled.
757
758           Available since 0.15.
759

WARNING

761       For maximum security, endeavour always to avoid ever looking at,
762       touching, or even imputing the existence of the filename.  You do not
763       know that that filename is connected to the same file as the handle you
764       have, and attempts to check this can only trigger more race conditions.
765       It's far more secure to use the filehandle alone and dispense with the
766       filename altogether.
767
768       If you need to pass the handle to something that expects a filename
769       then on a unix system you can use ""/dev/fd/" . fileno($fh)" for
770       arbitrary programs. Perl code that uses the 2-argument version of
771       "open" can be passed ""+<=&" . fileno($fh)". Otherwise you will need to
772       pass the filename. You will have to clear the close-on-exec bit on that
773       file descriptor before passing it to another process.
774
775           use Fcntl qw/F_SETFD F_GETFD/;
776           fcntl($tmpfh, F_SETFD, 0)
777               or die "Can't clear close-on-exec flag on temp fh: $!\n";
778
779   Temporary files and NFS
780       Some problems are associated with using temporary files that reside on
781       NFS file systems and it is recommended that a local filesystem is used
782       whenever possible. Some of the security tests will most probably fail
783       when the temp file is not local. Additionally, be aware that the
784       performance of I/O operations over NFS will not be as good as for a
785       local disk.
786
787   Forking
788       In some cases files created by File::Temp are removed from within an
789       END block. Since END blocks are triggered when a child process exits
790       (unless "POSIX::_exit()" is used by the child) File::Temp takes care to
791       only remove those temp files created by a particular process ID. This
792       means that a child will not attempt to remove temp files created by the
793       parent process.
794
795       If you are forking many processes in parallel that are all creating
796       temporary files, you may need to reset the random number seed using
797       srand(EXPR) in each child else all the children will attempt to walk
798       through the same set of random file names and may well cause themselves
799       to give up if they exceed the number of retry attempts.
800
801   Directory removal
802       Note that if you have chdir'ed into the temporary directory and it is
803       subsequently cleaned up (either in the END block or as part of object
804       destruction), then you will get a warning from File::Path::rmtree().
805
806   Taint mode
807       If you need to run code under taint mode, updating to the latest
808       File::Spec is highly recommended.  On Windows, if the directory given
809       by File::Spec::tmpdir isn't writable, File::Temp will attempt to
810       fallback to the user's local application data directory or croak with
811       an error.
812
813   BINMODE
814       The file returned by File::Temp will have been opened in binary mode if
815       such a mode is available. If that is not correct, use the "binmode()"
816       function to change the mode of the filehandle.
817
818       Note that you can modify the encoding of a file opened by File::Temp
819       also by using "binmode()".
820

HISTORY

822       Originally began life in May 1999 as an XS interface to the system
823       mkstemp() function. In March 2000, the OpenBSD mkstemp() code was
824       translated to Perl for total control of the code's security checking,
825       to ensure the presence of the function regardless of operating system
826       and to help with portability. The module was shipped as a standard part
827       of perl from v5.6.1.
828
829       Thanks to Tom Christiansen for suggesting that this module should be
830       written and providing ideas for code improvements and security
831       enhancements.
832

SEE ALSO

834       "tmpnam" in POSIX, "tmpfile" in POSIX, File::Spec, File::Path
835
836       See IO::File and File::MkTemp, Apache::TempFile for different
837       implementations of temporary file handling.
838
839       See File::Tempdir for an alternative object-oriented wrapper for the
840       "tempdir" function.
841

SUPPORT

843       Bugs may be submitted through the RT bug tracker
844       <https://rt.cpan.org/Public/Dist/Display.html?Name=File-Temp> (or
845       bug-File-Temp@rt.cpan.org <mailto:bug-File-Temp@rt.cpan.org>).
846
847       There is also a mailing list available for users of this distribution,
848       at <http://lists.perl.org/list/cpan-workers.html>.
849
850       There is also an irc channel available for users of this distribution,
851       at "#toolchain" on "irc.perl.org" <irc://irc.perl.org/#toolchain>.
852

AUTHOR

854       Tim Jenness <tjenness@cpan.org>
855

CONTRIBUTORS

857       ·   David Golden <dagolden@cpan.org>
858
859       ·   Karen Etheridge <ether@cpan.org>
860
861       ·   Slaven Rezic <slaven@rezic.de>
862
863       ·   Peter Rabbitson <ribasushi@cpan.org>
864
865       ·   Olivier Mengue <dolmen@cpan.org>
866
867       ·   David Golden <xdg@xdg.me>
868
869       ·   Kevin Ryde <user42@zip.com.au>
870
871       ·   Peter John Acklam <pjacklam@online.no>
872
873       ·   Slaven Rezic <slaven.rezic@idealo.de>
874
875       ·   James E. Keenan <jkeen@verizon.net>
876
877       ·   Brian Mowrey <brian@drlabs.org>
878
879       ·   Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
880
881       ·   David Steinbrunner <dsteinbrunner@pobox.com>
882
883       ·   Ed Avis <eda@linux01.wcl.local>
884
885       ·   Guillem Jover <guillem@hadrons.org>
886
887       ·   Ben Tilly <btilly@gmail.com>
888
890       This software is copyright (c) 2019 by Tim Jenness and the UK Particle
891       Physics and Astronomy Research Council.
892
893       This is free software; you can redistribute it and/or modify it under
894       the same terms as the Perl 5 programming language system itself.
895
896
897
898perl v5.30.1                      2020-01-30                     File::Temp(3)
Impressum