file::temp.3

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.IX Item "DESTROY"
When the object goes out of scope, the destructor is called. This
destructor will attempt to unlink the file (using \f(CW\*(C`unlink1\*(C'\fR)
if the constructor was called with \s-1UNLINK\s0 set to 1 (the default state
if \s-1UNLINK\s0 is not specified).
.Sp
No error is given if the unlink fails.
.Sp
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.
.Sp
For a temporary directory object the directory will be removed
unless the \s-1CLEANUP\s0 argument was used in the constructor (and set to
false) or \f(CW\*(C`unlink_on_destroy\*(C'\fR was modified after creation.
.Sp
If the global variable \f(CW$KEEP_ALL\fR is true, the file or directory
will not be removed.
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
This section describes the recommended interface for generating
temporary files and directories.
.IP "\fBtempfile\fR" 4
.IX Item "tempfile"
This is the basic function to generate temporary files.
The behaviour of the file can be changed using various options:
.Sp
.Vb 2
\&  $fh = tempfile();
\&  ($fh, $filename) = tempfile();
.Ve
.Sp
Create a temporary file in  the directory specified for temporary
files, as specified by the \fItmpdir()\fR function in File::Spec.
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template);
.Ve
.Sp
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.
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template, SUFFIX => $suffix)
.Ve
.Sp
Same as previously, except that a suffix is added to the template
after the `X' translation.  Useful for ensuring that a temporary
filename has a particular extension when needed by other applications.
But see the \s-1WARNING\s0 at the end.
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template, DIR => $dir);
.Ve
.Sp
Translates the template as before except that a directory name
is specified.
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template, TMPDIR => 1);
.Ve
.Sp
Equivalent to specifying a \s-1DIR\s0 of \*(L"File::Spec\->tmpdir\*(R", writing the file
into the same temporary directory as would be used if no template was
specified at all.
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template, UNLINK => 1);
.Ve
.Sp
Return the filename and filehandle as before except that the file is
automatically removed when the program exits (dependent on
\&\f(CW$KEEP_ALL\fR). Default is for the file to be removed if a file handle is
requested and to be kept if the filename is requested. In a scalar
context (where no filename is returned) the file is always deleted
either (depending on the operating system) on exit or when it is
closed (unless \f(CW$KEEP_ALL\fR is true when the temp file is created).
.Sp
Use the object-oriented interface if fine-grained control of when
a file is removed is required.
.Sp
If the template is not specified, a template is always
automatically generated. This temporary file is placed in \fItmpdir()\fR
(File::Spec) unless a directory is specified explicitly with the
\&\s-1DIR\s0 option.
.Sp
.Vb 1
\&  $fh = tempfile( DIR => $dir );
.Ve
.Sp
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 \fItmpfile()\fR 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
\&\s-1NT\s0 uses the \f(CW\*(C`O_TEMPORARY\*(C'\fR flag) the file is marked for deletion when
the program ends (equivalent to setting \s-1UNLINK\s0 to 1). The \f(CW\*(C`UNLINK\*(C'\fR
flag is ignored if present.
.Sp
.Vb 1
\&  (undef, $filename) = tempfile($template, OPEN => 0);
.Ve
.Sp
This will return the filename based on the template but
will not open this file.  Cannot be used in conjunction with
\&\s-1UNLINK\s0 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 \fItmpnam()\fR
and \fImktemp()\fR functions described elsewhere in this document
if opening the file is not required.
.Sp
If the operating system supports it (for example \s-1BSD\s0 derived systems), the 
filehandle will be opened with O_EXLOCK (open with exclusive file lock). 
This can sometimes cause problems if the intention is to pass the filename 
to another system that expects to take an exclusive lock itself (such as 
DBD::SQLite) whilst ensuring that the tempfile is not reused. In this 
situation the \*(L"\s-1EXLOCK\s0\*(R" option can be passed to tempfile. By default \s-1EXLOCK\s0 
will be true (this retains compatibility with earlier releases).
.Sp
.Vb 1
\&  ($fh, $filename) = tempfile($template, EXLOCK => 0);
.Ve
.Sp
Options can be combined as required.
.Sp
Will \fIcroak()\fR if there is an error.
.IP "\fBtempdir\fR" 4
.IX Item "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 \s-1CLEANUP\s0 option which will trigger removal on program
exit, or consider using the \*(L"newdir\*(R" method in the object interface which
will allow the directory to be cleaned up when the object goes out of
scope.
.Sp
The behaviour of the function depends on the arguments:
.Sp
.Vb 1
\&  $tempdir = tempdir();
.Ve
.Sp
Create a directory in \fItmpdir()\fR (see File::Spec).
.Sp
.Vb 1
\&  $tempdir = tempdir( $template );
.Ve
.Sp
Create a directory from the supplied template. This template is
similar to that described for \fItempfile()\fR. `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.
.Sp
.Vb 1
\&  $tempdir = tempdir ( DIR => $dir );
.Ve
.Sp
Specifies the directory to use for the temporary directory.
The temporary directory name is derived from an internal template.
.Sp
.Vb 1
\&  $tempdir = tempdir ( $template, DIR => $dir );
.Ve
.Sp
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.
.Sp
.Vb 1
\&  $tempdir = tempdir ( $template, TMPDIR => 1 );
.Ve
.Sp
Using the supplied template, create the temporary directory in
a standard location for temporary files. Equivalent to doing
.Sp
.Vb 1
\&  $tempdir = tempdir ( $template, DIR => File::Spec\->tmpdir);
.Ve
.Sp
but shorter. Parent directory specifications are stripped from the
template itself. The \f(CW\*(C`TMPDIR\*(C'\fR option is ignored if \f(CW\*(C`DIR\*(C'\fR is set
explicitly.  Additionally, \f(CW\*(C`TMPDIR\*(C'\fR is implied if neither a template
nor a directory are supplied.
.Sp
.Vb 1
\&  $tempdir = tempdir( $template, CLEANUP => 1);
.Ve
.Sp
Create a temporary directory using the supplied template, but
attempt to remove it (and all files inside it) when the program
exits. Note that an attempt will be made to remove all files from
the directory even if they were not created by this module (otherwise
why ask to clean it up?). The directory removal is made with
the \fIrmtree()\fR function from the File::Path module.
Of course, if the template is not specified, the temporary directory
will be created in \fItmpdir()\fR and will also be removed at program exit.
.Sp
Will \fIcroak()\fR if there is an error.
.SH "MKTEMP FUNCTIONS"
.IX Header "MKTEMP FUNCTIONS"
The following functions are Perl implementations of the
\&\fImktemp()\fR family of temp file generation system calls.
.IP "\fBmkstemp\fR" 4
.IX Item "mkstemp"
Given a template, returns a filehandle to the temporary file and the name
of the file.
.Sp
.Vb 1
\&  ($fh, $name) = mkstemp( $template );
.Ve
.Sp
In scalar context, just the filehandle is returned.
.Sp
The template may be any filename with some number of X's appended
to it, for example \fI/tmp/temp.XXXX\fR. The trailing X's are replaced
with unique alphanumeric combinations.
.Sp
Will \fIcroak()\fR if there is an error.
.IP "\fBmkstemps\fR" 4
.IX Item "mkstemps"
Similar to \fImkstemp()\fR, except that an extra argument can be supplied
with a suffix to be appended to the template.
.Sp
.Vb 1
\&  ($fh, $name) = mkstemps( $template, $suffix );
.Ve
.Sp
For example a template of \f(CW\*(C`testXXXXXX\*(C'\fR and suffix of \f(CW\*(C`.dat\*(C'\fR
would generate a file similar to \fItesthGji_w.dat\fR.
.Sp
Returns just the filehandle alone when called in scalar context.
.Sp
Will \fIcroak()\fR if there is an error.
.IP "\fBmkdtemp\fR" 4
.IX Item "mkdtemp"
Create a directory from a template. The template must end in
X's that are replaced by the routine.
.Sp
.Vb 1
\&  $tmpdir_name = mkdtemp($template);
.Ve
.Sp
Returns the name of the temporary directory created.
.Sp
Directory must be removed by the caller.
.Sp
Will \fIcroak()\fR if there is an error.
.IP "\fBmktemp\fR" 4
.IX Item "mktemp"
Returns a valid temporary filename but does not guarantee
that the file will not be opened by someone else.
.Sp
.Vb 1
\&  $unopened_file = mktemp($template);
.Ve
.Sp
Template is the same as that required by \fImkstemp()\fR.
.Sp
Will \fIcroak()\fR if there is an error.
.SH "POSIX FUNCTIONS"
.IX Header "POSIX FUNCTIONS"
This section describes the re-implementation of the \fItmpnam()\fR
and \fItmpfile()\fR functions described in \s-1POSIX\s0
using the \fImkstemp()\fR from this module.
.PP
Unlike the \s-1POSIX\s0 implementations, the directory used
for the temporary file is not specified in a system include
file (\f(CW\*(C`P_tmpdir\*(C'\fR) but simply depends on the choice of \fItmpdir()\fR
returned by File::Spec. On some implementations this
location can be set using the \f(CW\*(C`TMPDIR\*(C'\fR environment variable, which
may not be secure.
If this is a problem, simply use \fImkstemp()\fR and specify a template.
.IP "\fBtmpnam\fR" 4
.IX Item "tmpnam"
When called in scalar context, returns the full name (including path)
of a temporary file (uses \fImktemp()\fR). The only check is that the file does
not already exist, but there is no guarantee that that condition will
continue to apply.
.Sp
.Vb 1
\&  $file = tmpnam();
.Ve
.Sp
When called in list context, a filehandle to the open file and
a filename are returned. This is achieved by calling \fImkstemp()\fR
after constructing a suitable template.
.Sp
.Vb 1
\&  ($fh, $file) = tmpnam();
.Ve
.Sp
If possible, this form should be used to prevent possible
race conditions.
.Sp
See \*(L"tmpdir\*(R" in File::Spec for information on the choice of temporary
directory for a particular operating system.
.Sp
Will \fIcroak()\fR if there is an error.
.IP "\fBtmpfile\fR" 4
.IX Item "tmpfile"
Returns the filehandle of a temporary file.
.Sp
.Vb 1
\&  $fh = tmpfile();
.Ve
.Sp
The file is removed when the filehandle is closed or when the program
exits. No access to the filename is provided.
.Sp
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 \s-1NFS\s0 file system.
.Sp
Will \fIcroak()\fR if there is an error.
.SH "ADDITIONAL FUNCTIONS"
.IX Header "ADDITIONAL FUNCTIONS"
These functions are provided for backwards compatibility
with common tempfile generation C library functions.
.PP
They are not exported and must be addressed using the full package
name.
.IP "\fBtempnam\fR" 4
.IX Item "tempnam"