Creating a Temporary File (PHP Cookbook)

18.3. Creating a Temporary File

18.3.1. Problem

You need a file to temporarily hold some data.

18.3.2. Solution

Use tmpfile( ) if the file needs to last only the duration of the running script:

$temp_fh = tmpfile();
// write some data to the temp file
fputs($temp_fh,"The current time is ".strftime('%c'));
// the file goes away when the script ends
exit(1);

If the file needs to last longer, generate a filename with tempnam( ), and then use fopen( ):

$tempfilename = tempnam('/tmp','data-');
$temp_fh = fopen($tempfilename,'w') or die($php_errormsg);
fputs($temp_fh,"The current time is ".strftime('%c'));
fclose($temp_fh) or die($php_errormsg);

18.3.3. Discussion

The function tmpfile( ) creates a file with a unique name and returns a file handle. The file is removed when fclose( ) is called on that file handle, or the script ends.

Alternatively, tempnam( ) generates a filename. It takes two arguments: the first is a directory, and the second is a prefix for the filename. If the directory doesn't exist or isn't writeable, tempnam( ) uses the system temporary directory — the TMPDIR environment variable in Unix or the TMP environment variable in Windows. For example:

$tempfilename = tempnam('/tmp','data-');
print "Temporary data will be stored in $tempfilename";
Temporary data will be stored in /tmp/data-GawVoL

Because of the way PHP generates temporary filenames, the filename tempnam( ) returns is actually created but left empty, even if your script never explicitly opens the file. This ensures another program won't create a file with the same name between the time that you call tempnam( ) and the time you call fopen( ) with the filename.

18.3.4. See Also

Documentation on tmpfile( ) at http://www.php.net/tmpfile and on tempnam( ) at http://www.php.net/tempnam.