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

File::Temp(3p) Perl Programmers Reference Guide File::Temp(3p) #

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

NNAAMMEE #

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

VVEERRSSIIOONN #

 version 0.2311

SSYYNNOOPPSSIISS #

   use File::Temp qw/ tempfile tempdir /;

   $fh = tempfile();
   ($fh, $filename) = tempfile();

   ($fh, $filename) = tempfile( $template, DIR => $dir);
   ($fh, $filename) = tempfile( $template, SUFFIX => '.dat');
   ($fh, $filename) = tempfile( $template, TMPDIR => 1 );

   binmode( $fh, ":utf8" );

   $dir = tempdir( CLEANUP => 1 );
   ($fh, $filename) = tempfile( DIR => $dir );

 Object interface:

   require File::Temp;
   use File::Temp ();
   use File::Temp qw/ :seekable /;

   $fh = File::Temp->new();
   $fname = $fh->filename;

   $fh = File::Temp->new(TEMPLATE => $template);
   $fname = $fh->filename;

   $tmp = File::Temp->new( UNLINK => 0, SUFFIX => '.dat' );
   print $tmp "Some data\n";
   print "Filename is $tmp\n";
   $tmp->seek( 0, SEEK_END );

   $dir = File::Temp->newdir(); # CLEANUP => 1 by default

 The following interfaces are provided for compatibility with existing
 APIs. They should not be used in new code.

 MkTemp family:

   use File::Temp qw/ :mktemp  /;

   ($fh, $file) = mkstemp( "tmpfileXXXXX" );
   ($fh, $file) = mkstemps( "tmpfileXXXXXX", $suffix);

   $tmpdir = mkdtemp( $template );

   $unopened_file = mktemp( $template );

 POSIX functions:

   use File::Temp qw/ :POSIX /;

   $file = tmpnam();
   $fh = tmpfile();

   ($fh, $file) = tmpnam();

 Compatibility functions:

   $unopened_file = File::Temp::tempnam( $dir, $pfx );

DDEESSCCRRIIPPTTIIOONN #

 "File::Temp" can be used to create and open temporary files in a safe
 way.  There is both a function interface and an object-oriented
 interface.  The File::Temp constructor or the tteemmppffiillee(()) function can be
 used to return the name and the open filehandle of a temporary file.  The
 tteemmppddiirr(()) function can be used to create a temporary directory.

 The security aspect of temporary file creation is emphasized such that a
 filehandle and filename are returned together.  This helps guarantee that
 a race condition can not occur where the temporary file is created by
 another process between checking for the existence of the file and its
 opening.  Additional security levels are provided to check, for example,
 that the sticky bit is set on world writable directories.  See
 "safe_level" for more information.

 For compatibility with popular C library functions, Perl implementations
 of the mmkksstteemmpp(()) family of functions are provided. These are, mmkksstteemmpp(()),
 mmkksstteemmppss(()), mmkkddtteemmpp(()) and mmkktteemmpp(()).

 Additionally, implementations of the standard POSIX ttmmppnnaamm(()) and
 ttmmppffiillee(()) functions are provided if required.

 Implementations of mmkktteemmpp(()), ttmmppnnaamm(()), and tteemmppnnaamm(()) are provided, but
 should be used with caution since they return only a filename that was
 valid when function was called, so cannot guarantee that the file will
 not exist by the time the caller opens the filename.

 Filehandles returned by these functions support the seekable methods.

OOBBJJEECCTT--OORRIIEENNTTEEDD IINNTTEERRFFAACCEE #

 This is the primary interface for interacting with "File::Temp". Using
 the OO interface a temporary file can be created when the object is
 constructed and the file can be removed when the object is no longer
 required.

 Note that there is no method to obtain the filehandle from the
 "File::Temp" object. The object itself acts as a filehandle.  The object
 isa "IO::Handle" and isa "IO::Seekable" so all those methods are
 available.

 Also, the object is configured such that it stringifies to the name of
 the temporary file and so can be compared to a filename directly.  It
 numifies to the "refaddr" the same as other handles and so can be
 compared to other handles with "==".

     $fh eq $filename       # as a string
     $fh != \*STDOUT        # as a number

 Available since 0.14.

 nneeww Create a temporary file object.

       my $tmp = File::Temp->new();

     by default the object is constructed as if "tempfile" was called
     without options, but with the additional behaviour that the temporary
     file is removed by the object destructor if UNLINK is set to true
     (the default).

     Supported arguments are the same as for "tempfile": UNLINK
     (defaulting to true), DIR, EXLOCK, PERMS and SUFFIX. Additionally,
     the filename template is specified using the TEMPLATE option. The
     OPEN option is not supported (the file is always opened).

      $tmp = File::Temp->new( TEMPLATE => 'tempXXXXX',
                             DIR => 'mydir',
                             SUFFIX => '.dat');

     Arguments are case insensitive.

     Can call ccrrooaakk(()) if an error occurs.

     Available since 0.14.

     TEMPLATE available since 0.23

 nneewwddiirr
     Create a temporary directory using an object oriented interface.

       $dir = File::Temp->newdir();

     By default the directory is deleted when the object goes out of
     scope.

     Supports the same options as the "tempdir" function. Note that
     directories created with this method default to CLEANUP => 1.

       $dir = File::Temp->newdir( $template, %options );

     A template may be specified either with a leading template or with a
     TEMPLATE argument.

     Available since 0.19.

     TEMPLATE available since 0.23.

 ffiilleennaammee
     Return the name of the temporary file associated with this object (if
     the object was created using the "new" constructor).

       $filename = $tmp->filename;

     This method is called automatically when the object is used as a
     string.

     Current API available since 0.14

 ddiirrnnaammee
     Return the name of the temporary directory associated with this
     object (if the object was created using the "newdir" constructor).

       $dirname = $tmpdir->dirname;

     This method is called automatically when the object is used in string
     context.

 uunnlliinnkk__oonn__ddeessttrrooyy
     Control whether the file is unlinked when the object goes out of
     scope.  The file is removed if this value is true and $KEEP_ALL is
     not.

      $fh->unlink_on_destroy( 1 );

     Default is for the file to be removed.

     Current API available since 0.15

DDEESSTTRROOYY #

     When the object goes out of scope, the destructor is called. This
     destructor will attempt to unlink the file (using unlink1) if the
     constructor was called with UNLINK set to 1 (the default state if
     UNLINK is not specified).

     No error is given if the unlink fails.

     If the object has been passed to a child process during a fork, the
     file will be deleted when the object goes out of scope in the parent.

     For a temporary directory object the directory will be removed unless
     the CLEANUP argument was used in the constructor (and set to false)
     or "unlink_on_destroy" was modified after creation.  Note that if a
     temp directory is your current directory, it cannot be removed - a
     warning will be given in this case.  "chdir()" out of the directory
     before letting the object go out of scope.

     If the global variable $KEEP_ALL is true, the file or directory will
     not be removed.

FFUUNNCCTTIIOONNSS #

 This section describes the recommended interface for generating temporary
 files and directories.

 tteemmppffiillee
     This is the basic function to generate temporary files.  The
     behaviour of the file can be changed using various options:

       $fh = tempfile();
       ($fh, $filename) = tempfile();

     Create a temporary file in  the directory specified for temporary
     files, as specified by the ttmmppddiirr(()) function in File::Spec.

       ($fh, $filename) = tempfile($template);

     Create a temporary file in the current directory using the supplied
     template.  Trailing `X' characters are replaced with random letters
     to generate the filename.  At least four `X' characters must be
     present at the end of the template.

       ($fh, $filename) = tempfile($template, SUFFIX => $suffix)

     Same as previously, except that a suffix is added to the template
     after the `X' translation.  Useful for ensuring that a temporary
     filename has a particular extension when needed by other
     applications.  But see the WARNING at the end.

       ($fh, $filename) = tempfile($template, DIR => $dir);

     Translates the template as before except that a directory name is
     specified.

       ($fh, $filename) = tempfile($template, TMPDIR => 1);

     Equivalent to specifying a DIR of "File::Spec->tmpdir", writing the
     file into the same temporary directory as would be used if no
     template was specified at all.

       ($fh, $filename) = tempfile($template, UNLINK => 1);

     Return the filename and filehandle as before except that the file is
     automatically removed when the program exits (dependent on
     $KEEP_ALL). Default is for the file to be removed if a file handle is
     requested and to be kept if the filename is requested. In a scalar
     context (where no filename is returned) the file is always deleted
     either (depending on the operating system) on exit or when it is
     closed (unless $KEEP_ALL is true when the temp file is created).

     Use the object-oriented interface if fine-grained control of when a
     file is removed is required.

     If the template is not specified, a template is always automatically
     generated. This temporary file is placed in ttmmppddiirr(()) (File::Spec)
     unless a directory is specified explicitly with the DIR option.

       $fh = tempfile( DIR => $dir );

     If called in scalar context, only the filehandle is returned and the
     file will automatically be deleted when closed on operating systems
     that support this (see the description of ttmmppffiillee(()) elsewhere in this
     document).  This is the preferred mode of operation, as if you only
     have a filehandle, you can never create a race condition by fumbling
     with the filename. On systems that can not unlink an open file or can
     not mark a file as temporary when it is opened (for example, Windows
     NT uses the "O_TEMPORARY" flag) the file is marked for deletion when
     the program ends (equivalent to setting UNLINK to 1). The "UNLINK"
     flag is ignored if present.

       (undef, $filename) = tempfile($template, OPEN => 0);

     This will return the filename based on the template but will not open
     this file.  Cannot be used in conjunction with UNLINK set to true.
     Default is to always open the file to protect from possible race
     conditions. A warning is issued if warnings are turned on. Consider
     using the ttmmppnnaamm(()) and mmkktteemmpp(()) functions described elsewhere in this
     document if opening the file is not required.

     To open the temporary filehandle with O_EXLOCK (open with exclusive
     file lock) use "EXLOCK=>1". This is supported only by some operating
     systems (most notably BSD derived systems). By default EXLOCK will be
     false. Former "File::Temp" versions set EXLOCK to true, so to be sure
     to get an unlocked filehandle also with older versions, explicitly
     set "EXLOCK=>0".

       ($fh, $filename) = tempfile($template, EXLOCK => 1);

     By default, the temp file is created with 0600 file permissions.  Use
     "PERMS" to change this:

       ($fh, $filename) = tempfile($template, PERMS => 0666);

     Options can be combined as required.

     Will ccrrooaakk(()) if there is an error.

     Available since 0.05.

     UNLINK flag available since 0.10.

     TMPDIR flag available since 0.19.

     EXLOCK flag available since 0.19.

     PERMS flag available since 0.2310.

 tteemmppddiirr
     This is the recommended interface for creation of temporary
     directories.  By default the directory will not be removed on exit
     (that is, it won't be temporary; this behaviour can not be changed
     because of issues with backwards compatibility). To enable removal
     either use the CLEANUP option which will trigger removal on program
     exit, or consider using the "newdir" method in the object interface
     which will allow the directory to be cleaned up when the object goes
     out of scope.

     The behaviour of the function depends on the arguments:

       $tempdir = tempdir();

     Create a directory in ttmmppddiirr(()) (see File::Spec).

       $tempdir = tempdir( $template );

     Create a directory from the supplied template. This template is
     similar to that described for tteemmppffiillee(()). `X' characters at the end
     of the template are replaced with random letters to construct the
     directory name. At least four `X' characters must be in the template.

       $tempdir = tempdir ( DIR => $dir );

     Specifies the directory to use for the temporary directory.  The
     temporary directory name is derived from an internal template.

       $tempdir = tempdir ( $template, DIR => $dir );

     Prepend the supplied directory name to the template. The template
     should not include parent directory specifications itself. Any parent
     directory specifications are removed from the template before
     prepending the supplied directory.

       $tempdir = tempdir ( $template, TMPDIR => 1 );

     Using the supplied template, create the temporary directory in a
     standard location for temporary files. Equivalent to doing

       $tempdir = tempdir ( $template, DIR => File::Spec->tmpdir);

     but shorter. Parent directory specifications are stripped from the
     template itself. The "TMPDIR" option is ignored if "DIR" is set
     explicitly.  Additionally, "TMPDIR" is implied if neither a template
     nor a directory are supplied.

       $tempdir = tempdir( $template, CLEANUP => 1);

     Create a temporary directory using the supplied template, but attempt
     to remove it (and all files inside it) when the program exits. Note
     that an attempt will be made to remove all files from the directory
     even if they were not created by this module (otherwise why ask to
     clean it up?). The directory removal is made with the rrmmttrreeee(())
     function from the File::Path module.  Of course, if the template is
     not specified, the temporary directory will be created in ttmmppddiirr(())
     and will also be removed at program exit.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

MMKKTTEEMMPP FFUUNNCCTTIIOONNSS #

 The following functions are Perl implementations of the mmkktteemmpp(()) family
 of temp file generation system calls.

 mmkksstteemmpp
     Given a template, returns a filehandle to the temporary file and the
     name of the file.

       ($fh, $name) = mkstemp( $template );

     In scalar context, just the filehandle is returned.

     The template may be any filename with some number of X's appended to
     it, for example _/_t_m_p_/_t_e_m_p_._X_X_X_X. The trailing X's are replaced with
     unique alphanumeric combinations.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

 mmkksstteemmppss
     Similar to mmkksstteemmpp(()), except that an extra argument can be supplied
     with a suffix to be appended to the template.

       ($fh, $name) = mkstemps( $template, $suffix );

     For example a template of "testXXXXXX" and suffix of ".dat" would
     generate a file similar to _t_e_s_t_h_G_j_i___w_._d_a_t.

     Returns just the filehandle alone when called in scalar context.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

 mmkkddtteemmpp
     Create a directory from a template. The template must end in X's that
     are replaced by the routine.

       $tmpdir_name = mkdtemp($template);

     Returns the name of the temporary directory created.

     Directory must be removed by the caller.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

 mmkktteemmpp
     Returns a valid temporary filename but does not guarantee that the
     file will not be opened by someone else.

       $unopened_file = mktemp($template);

     Template is the same as that required by mmkksstteemmpp(()).

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

PPOOSSIIXX FFUUNNCCTTIIOONNSS #

 This section describes the re-implementation of the ttmmppnnaamm(()) and
 ttmmppffiillee(()) functions described in POSIX using the mmkksstteemmpp(()) from this
 module.

 Unlike the POSIX implementations, the directory used for the temporary
 file is not specified in a system include file ("P_tmpdir") but simply
 depends on the choice of ttmmppddiirr(()) returned by File::Spec. On some
 implementations this location can be set using the "TMPDIR" environment
 variable, which may not be secure.  If this is a problem, simply use
 mmkksstteemmpp(()) and specify a template.

 ttmmppnnaamm
     When called in scalar context, returns the full name (including path)
     of a temporary file (uses mmkktteemmpp(())). The only check is that the file
     does not already exist, but there is no guarantee that that condition
     will continue to apply.

       $file = tmpnam();

     When called in list context, a filehandle to the open file and a
     filename are returned. This is achieved by calling mmkksstteemmpp(()) after
     constructing a suitable template.

       ($fh, $file) = tmpnam();

     If possible, this form should be used to prevent possible race
     conditions.

     See "tmpdir" in File::Spec for information on the choice of temporary
     directory for a particular operating system.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

 ttmmppffiillee
     Returns the filehandle of a temporary file.

       $fh = tmpfile();

     The file is removed when the filehandle is closed or when the program
     exits. No access to the filename is provided.

     If the temporary file can not be created undef is returned.
     Currently this command will probably not work when the temporary
     directory is on an NFS file system.

     Will ccrrooaakk(()) if there is an error.

     Available since 0.05.

     Returning undef if unable to create file added in 0.12.

AADDDDIITTIIOONNAALL FFUUNNCCTTIIOONNSS #

 These functions are provided for backwards compatibility with common
 tempfile generation C library functions.

 They are not exported and must be addressed using the full package name.

 tteemmppnnaamm
     Return the name of a temporary file in the specified directory using
     a prefix. The file is guaranteed not to exist at the time the
     function was called, but such guarantees are good for one clock tick
     only.  Always use the proper form of "sysopen" with "O_CREAT |
     O_EXCL" if you must open such a filename.

       $filename = File::Temp::tempnam( $dir, $prefix );

     Equivalent to running mmkktteemmpp(()) with $dir/$prefixXXXXXXXX (using unix
     file convention as an example)

     Because this function uses mmkktteemmpp(()), it can suffer from race
     conditions.

     Will ccrrooaakk(()) if there is an error.

     Current API available since 0.05.

UUTTIILLIITTYY FFUUNNCCTTIIOONNSS #

 Useful functions for dealing with the filehandle and filename.

 uunnlliinnkk00
     Given an open filehandle and the associated filename, make a safe
     unlink. This is achieved by first checking that the filename and
     filehandle initially point to the same file and that the number of
     links to the file is 1 (all fields returned by ssttaatt(()) are compared).
     Then the filename is unlinked and the filehandle checked once again
     to verify that the number of links on that file is now 0.  This is
     the closest you can come to making sure that the filename unlinked
     was the same as the file whose descriptor you hold.

       unlink0($fh, $path)
          or die "Error unlinking file $path safely";

     Returns false on error but ccrrooaakkss(()) if there is a security anomaly.
     The filehandle is not closed since on some occasions this is not
     required.

     On some platforms, for example Windows NT, it is not possible to
     unlink an open file (the file must be closed first). On those
     platforms, the actual unlinking is deferred until the program ends
     and good status is returned. A check is still performed to make sure
     that the filehandle and filename are pointing to the same thing (but
     not at the time the end block is executed since the deferred removal
     may not have access to the filehandle).

     Additionally, on Windows NT not all the fields returned by ssttaatt(()) can
     be compared. For example, the "dev" and "rdev" fields seem to be
     different.  Also, it seems that the size of the file returned by
     ssttaatt(()) does not always agree, with "stat(FH)" being more accurate
     than "stat(filename)", presumably because of caching issues even when
     using autoflush (this is usually overcome by waiting a while after
     writing to the tempfile before attempting to "unlink0" it).

     Finally, on NFS file systems the link count of the file handle does
     not always go to zero immediately after unlinking. Currently, this
     command is expected to fail on NFS disks.

     This function is disabled if the global variable $KEEP_ALL is true
     and an unlink on open file is supported. If the unlink is to be
     deferred to the END block, the file is still registered for removal.

     This function should not be called if you are using the object
     oriented interface since the it will interfere with the object
     destructor deleting the file.

     Available Since 0.05.

     If can not unlink open file, defer removal until later available
     since 0.06.

 ccmmppssttaatt
     Compare "stat" of filehandle with "stat" of provided filename.  This
     can be used to check that the filename and filehandle initially point
     to the same file and that the number of links to the file is 1 (all
     fields returned by ssttaatt(()) are compared).

       cmpstat($fh, $path)
          or die "Error comparing handle with file";

     Returns false if the stat information differs or if the link count is
     greater than 1. Calls croak if there is a security anomaly.

     On certain platforms, for example Windows, not all the fields
     returned by ssttaatt(()) can be compared. For example, the "dev" and "rdev"
     fields seem to be different in Windows.  Also, it seems that the size
     of the file returned by ssttaatt(()) does not always agree, with "stat(FH)"
     being more accurate than "stat(filename)", presumably because of
     caching issues even when using autoflush (this is usually overcome by
     waiting a while after writing to the tempfile before attempting to
     "unlink0" it).

     Not exported by default.

     Current API available since 0.14.

 uunnlliinnkk11
     Similar to "unlink0" except after file comparison using cmpstat, the
     filehandle is closed prior to attempting to unlink the file. This
     allows the file to be removed without using an END block, but does
     mean that the post-unlink comparison of the filehandle state provided
     by "unlink0" is not available.

       unlink1($fh, $path)
          or die "Error closing and unlinking file";

     Usually called from the object destructor when using the OO
     interface.

     Not exported by default.

     This function is disabled if the global variable $KEEP_ALL is true.

     Can call ccrrooaakk(()) if there is a security anomaly during the ssttaatt(())
     comparison.

     Current API available since 0.14.

 cclleeaannuupp
     Calling this function will cause any temp files or temp directories
     that are registered for removal to be removed. This happens
     automatically when the process exits but can be triggered manually if
     the caller is sure that none of the temp files are required. This
     method can be registered as an Apache callback.

     Note that if a temp directory is your current directory, it cannot be
     removed.  "chdir()" out of the directory first before calling
     "cleanup()". (For the cleanup at program exit when the CLEANUP flag
     is set, this happens automatically.)

     On OSes where temp files are automatically removed when the temp file
     is closed, calling this function will have no effect other than to
     remove temporary directories (which may include temporary files).

       File::Temp::cleanup();

     Not exported by default.

     Current API available since 0.15.

PPAACCKKAAGGEE VVAARRIIAABBLLEESS #

 These functions control the global state of the package.

 ssaaffee__lleevveell
     Controls the lengths to which the module will go to check the safety
     of the temporary file or directory before proceeding.  Options are:

STANDARD #

             Do the basic security measures to ensure the directory exists
             and is writable, that temporary files are opened only if they
             do not already exist, and that possible race conditions are
             avoided.  Finally the unlink0 function is used to remove
             files safely.

     MEDIUM  In addition to the STANDARD security, the output directory is
             checked to make sure that it is owned either by root or the
             user running the program. If the directory is writable by
             group or by other, it is then checked to make sure that the
             sticky bit is set.

             Will not work on platforms that do not support the "-k" test
             for sticky bit.

     HIGH    In addition to the MEDIUM security checks, also check for the
             possibility of ``cchhoowwnn(()) giveaway'' using the POSIX ssyyssccoonnff(())
             function. If this is a possibility, each directory in the
             path is checked in turn for safeness, recursively walking
             back to the root directory.

             For platforms that do not support the POSIX
             "_PC_CHOWN_RESTRICTED" symbol (for example, Windows NT) it is
             assumed that ``cchhoowwnn(()) giveaway'' is possible and the
             recursive test is performed.

     The level can be changed as follows:

       File::Temp->safe_level( File::Temp::HIGH );

     The level constants are not exported by the module.

     Currently, you must be running at least perl v5.6.0 in order to run
     with MEDIUM or HIGH security. This is simply because the safety tests
     use functions from Fcntl that are not available in older versions of
     perl. The problem is that the version number for Fcntl is the same in
     perl 5.6.0 and in 5.005_03 even though they are different versions.

     On systems that do not support the HIGH or MEDIUM safety levels (for
     example Win NT or OS/2) any attempt to change the level will be
     ignored. The decision to ignore rather than raise an exception allows
     portable programs to be written with high security in mind for the
     systems that can support this without those programs failing on
     systems where the extra tests are irrelevant.

     If you really need to see whether the change has been accepted simply
     examine the return value of "safe_level".

       $newlevel = File::Temp->safe_level( File::Temp::HIGH );
       die "Could not change to high security"
           if $newlevel != File::Temp::HIGH;

     Available since 0.05.

 TopSystemUID
     This is the highest UID on the current system that refers to a root
     UID. This is used to make sure that the temporary directory is owned
     by a system UID ("root", "bin", "sys" etc) rather than simply by
     root.

     This is required since on many unix systems "/tmp" is not owned by
     root.

     Default is to assume that any UID less than or equal to 10 is a root

UID. #

       File::Temp->top_system_uid(10);
       my $topid = File::Temp->top_system_uid;

     This value can be adjusted to reduce security checking if required.
     The value is only relevant when "safe_level" is set to MEDIUM or
     higher.

     Available since 0.05.

$$KKEEEEPP__AALLLL #

     Controls whether temporary files and directories should be retained
     regardless of any instructions in the program to remove them
     automatically.  This is useful for debugging but should not be used
     in production code.

       $File::Temp::KEEP_ALL = 1;

     Default is for files to be removed as requested by the caller.

     In some cases, files will only be retained if this variable is true
     when the file is created. This means that you can not create a
     temporary file, set this variable and expect the temp file to still
     be around when the program exits.

$$DDEEBBUUGG #

     Controls whether debugging messages should be enabled.

       $File::Temp::DEBUG = 1;

     Default is for debugging mode to be disabled.

     Available since 0.15.

WWAARRNNIINNGG #

 For maximum security, endeavour always to avoid ever looking at,
 touching, or even imputing the existence of the filename.  You do not
 know that that filename is connected to the same file as the handle you
 have, and attempts to check this can only trigger more race conditions.
 It's far more secure to use the filehandle alone and dispense with the
 filename altogether.

 If you need to pass the handle to something that expects a filename then
 on a unix system you can use ""/dev/fd/" . fileno($fh)" for arbitrary
 programs. Perl code that uses the 2-argument version of "open" can be
 passed ""+<=&" . fileno($fh)". Otherwise you will need to pass the
 filename. You will have to clear the close-on-exec bit on that file
 descriptor before passing it to another process.

     use Fcntl qw/F_SETFD F_GETFD/;
     fcntl($tmpfh, F_SETFD, 0)
         or die "Can't clear close-on-exec flag on temp fh: $!\n";

TTeemmppoorraarryy ffiilleess aanndd NNFFSS Some problems are associated with using temporary files that reside on NFS file systems and it is recommended that a local filesystem is used whenever possible. Some of the security tests will most probably fail when the temp file is not local. Additionally, be aware that the performance of I/O operations over NFS will not be as good as for a local disk.

FFoorrkkiinngg In some cases files created by File::Temp are removed from within an END block. Since END blocks are triggered when a child process exits (unless “POSIX::_exit()” is used by the child) File::Temp takes care to only remove those temp files created by a particular process ID. This means that a child will not attempt to remove temp files created by the parent process.

 If you are forking many processes in parallel that are all creating
 temporary files, you may need to reset the random number seed using
 srand(EXPR) in each child else all the children will attempt to walk
 through the same set of random file names and may well cause themselves
 to give up if they exceed the number of retry attempts.

DDiirreeccttoorryy rreemmoovvaall Note that if you have chdir’ed into the temporary directory and it is subsequently cleaned up (either in the END block or as part of object destruction), then you will get a warning from FFiillee::::PPaatthh::::rrmmttrreeee(()).

TTaaiinntt mmooddee If you need to run code under taint mode, updating to the latest File::Spec is highly recommended. On Windows, if the directory given by File::Spec::tmpdir isn’t writable, File::Temp will attempt to fallback to the user’s local application data directory or croak with an error.

BBIINNMMOODDEE #

 The file returned by File::Temp will have been opened in binary mode if
 such a mode is available. If that is not correct, use the "binmode()"
 function to change the mode of the filehandle.

 Note that you can modify the encoding of a file opened by File::Temp also
 by using "binmode()".

HHIISSTTOORRYY #

 Originally began life in May 1999 as an XS interface to the system
 mmkksstteemmpp(()) function. In March 2000, the OpenBSD mmkksstteemmpp(()) code was
 translated to Perl for total control of the code's security checking, to
 ensure the presence of the function regardless of operating system and to
 help with portability. The module was shipped as a standard part of perl
 from v5.6.1.

 Thanks to Tom Christiansen for suggesting that this module should be
 written and providing ideas for code improvements and security
 enhancements.

SSEEEE AALLSSOO #

 "tmpnam" in POSIX, "tmpfile" in POSIX, File::Spec, File::Path

 See IO::File and File::MkTemp, Apache::TempFile for different
 implementations of temporary file handling.

 See File::Tempdir for an alternative object-oriented wrapper for the
 "tempdir" function.

SSUUPPPPOORRTT #

 Bugs may be submitted through the RT bug tracker
 <https://rt.cpan.org/Public/Dist/Display.html?Name=File-Temp> (or
 bug-File-Temp@rt.cpan.org <mailto:bug-File-Temp@rt.cpan.org>).

 There is also a mailing list available for users of this distribution, at
 <http://lists.perl.org/list/cpan-workers.html>.

 There is also an irc channel available for users of this distribution, at
 "#toolchain" on "irc.perl.org" <irc://irc.perl.org/#toolchain>.

AAUUTTHHOORR #

 Tim Jenness <tjenness@cpan.org>

CCOONNTTRRIIBBUUTTOORRSS #

 •   Tim Jenness <t.jenness@jach.hawaii.edu>

 •   Karen Etheridge <ether@cpan.org>

 •   David Golden <dagolden@cpan.org>

 •   Slaven Rezic <srezic@cpan.org>

 •   mohawk2 <mohawk2@users.noreply.github.com>

 •   Roy Ivy III <rivy.dev@gmail.com>

 •   Peter Rabbitson <ribasushi@cpan.org>

 •   Olivier Mengué <dolmen@cpan.org>

 •   Peter John Acklam <pjacklam@online.no>

 •   Tim Gim Yee <tim.gim.yee@gmail.com>

 •   Nicolas R <atoomic@cpan.org>

 •   Brian Mowrey <brian@drlabs.org>

 •   Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>

 •   David Steinbrunner <dsteinbrunner@pobox.com>

 •   Ed Avis <eda@linux01.wcl.local>

 •   Guillem Jover <guillem@hadrons.org>

 •   James E. Keenan <jkeen@verizon.net>

 •   Kevin Ryde <user42@zip.com.au>

 •   Ben Tilly <btilly@gmail.com>

CCOOPPYYRRIIGGHHTT AANNDD LLIICCEENNSSEE #

 This software is copyright (c) 2020 by Tim Jenness and the UK Particle
 Physics and Astronomy Research Council.

 This is free software; you can redistribute it and/or modify it under the
 same terms as the Perl 5 programming language system itself.

perl v5.36.3 2023-02-15 File::Temp(3p)