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

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

VERSION
       version 0.2311

SYNOPSIS
         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 );

DESCRIPTION
       "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 tempfile() function can be
       used to return the name and the open filehandle of a temporary file.
       The tempdir() 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 mkstemp() family of functions are provided. These are, mkstemp(),
       mkstemps(), mkdtemp() and mktemp().

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

       Implementations of mktemp(), tmpnam(), and tempnam() 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.

OBJECT-ORIENTED INTERFACE
       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.

       new 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 croak() if an error occurs.

           Available since 0.14.

           TEMPLATE available since 0.23

       newdir
           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.

       filename
           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

       dirname
           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.

       unlink_on_destroy
           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

       DESTROY
           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.

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

       tempfile
           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 tmpdir() 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  tmpdir()  (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  tmpfile()  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  tmpnam()  and  mktemp()  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 croak() 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.

       tempdir
           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 tmpdir() (see File::Spec).

             $tempdir = tempdir( $template );

           Create  a  directory  from  the  supplied template. This template is
           similar to that described for tempfile(). `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 rmtree() function from the File::Path module.   Of  course,
           if  the  template  is not specified, the temporary directory will be
           created in tmpdir() and will also be removed at program exit.

           Will croak() if there is an error.

           Current API available since 0.05.

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

       mkstemp
           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 /tmp/temp.XXXX. The trailing X's are replaced with
           unique alphanumeric combinations.

           Will croak() if there is an error.

           Current API available since 0.05.

       mkstemps
           Similar to mkstemp(), 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 testhGji_w.dat.

           Returns just the filehandle alone when called in scalar context.

           Will croak() if there is an error.

           Current API available since 0.05.

       mkdtemp
           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 croak() if there is an error.

           Current API available since 0.05.

       mktemp
           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 mkstemp().

           Will croak() if there is an error.

           Current API available since 0.05.

POSIX FUNCTIONS
       This  section  describes  the  re-implementation  of  the  tmpnam()  and
       tmpfile()  functions  described  in  POSIX using the mkstemp() 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  tmpdir()  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
       mkstemp() and specify a template.

       tmpnam
           When  called  in  scalar  context,  returns the full name (including
           path) of a temporary file (uses mktemp()). 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  mkstemp()  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 croak() if there is an error.

           Current API available since 0.05.

       tmpfile
           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 croak() if there is an error.

           Available since 0.05.

           Returning undef if unable to create file added in 0.12.

ADDITIONAL FUNCTIONS
       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.

       tempnam
           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 mktemp() with $dir/$prefixXXXXXXXX (using unix
           file convention as an example)

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

           Will croak() if there is an error.

           Current API available since 0.05.

UTILITY FUNCTIONS
       Useful functions for dealing with the filehandle and filename.

       unlink0
           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 stat() 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 croaks() 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 stat()
           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
           stat() 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.

       cmpstat
           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 stat() 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  stat()  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 stat() 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.

       unlink1
           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 croak() if there is a security anomaly  during  the  stat()
           comparison.

           Current API available since 0.14.

       cleanup
           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.

PACKAGE VARIABLES
       These functions control the global state of the package.

       safe_level
           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  ``chown()  giveaway''  using the POSIX
                   sysconf() 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  ``chown()  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.

       $KEEP_ALL
           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.

       $DEBUG
           Controls whether debugging messages should be enabled.

             $File::Temp::DEBUG = 1;

           Default is for debugging mode to be disabled.

           Available since 0.15.

WARNING
       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";

   Temporary files and NFS
       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.

   Forking
       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.

   Directory removal
       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 File::Path::rmtree().

   Taint mode
       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.

   BINMODE
       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().

HISTORY
       Originally  began  life  in  May  1999  as an XS interface to the system
       mkstemp() function. In  March  2000,  the  OpenBSD  mkstemp()  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.

SEE ALSO
       "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.

SUPPORT
       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>.

AUTHOR
       Tim Jenness <tjenness@cpan.org>

CONTRIBUTORS
       •   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>

COPYRIGHT AND LICENSE
       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 v5.40.1                       2026-08-30                 File::Temp(3perl)

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