Create a temp file with a specific extension using php

Question

How do I create a temporary file with a specified extension in php. I came across tempnam() but using it the extension can't be specified.

No, you can't specify an extension to tempname(), you will have to create your custom function for this, have a look at User Contributed Notes at theserverpages.com/php/manual/en/function.tempnam.php — Cyclonecode
– Cyclonecode, Commented Jan 23, 2012 at 11:35

nathan hayfield · Accepted Answer · 2017-05-04 21:06:23Z

52

Easiest way i have found is to create tempfile and then just rename it. For example:

 $tmpfname = tempnam(sys_get_temp_dir(), "Pre_");
 rename($tmpfname, $tmpfname .= '.pdf');

answered May 4, 2017 at 21:06

nathan hayfield

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3 Comments

nathan hayfield Over a year ago

Also rename returns true for success and false for failure so that is probably pretty useful as well.

DurandA Over a year ago

As explained in @CrimsonNosedAnole answer, there is an edge case where tempnam() + extension might not be unique.

nathan hayfield Over a year ago

@DurandA I would be shocked if that edge case ever happens. Anyway rename would return false in that scenario, so you can just check.

Michel Ayres · Accepted Answer · 2014-04-15 17:08:39Z

15

my way is using tempnam

$file = tempnam(sys_get_temp_dir(), 'prefix');
file_put_contents($file.'.extension', $data);
{
   //use your file
}
unlink($file);//to delete an empty file that tempnam creates
unlink($file.'.extension');//to delete your file

edited Apr 15, 2014 at 17:08

Michel Ayres

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answered Feb 7, 2014 at 16:46

Yasmany Hernandez Hernandez

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3 Comments

Dmitry Ginzburg Over a year ago

Also, it would be quite useful to unlink ($file) not to create random trash in /tmp

hytromo Over a year ago

I don't think this is safe. tempnam() ensures that $file doesn't exist. $file . '.extension' may as well exist.

rymo Over a year ago

As long as you use a sufficiently unique prefix and are consistent with its use it should be safe; unique-prefix-[tempnam-output].extension is only created after unique-prefix-[tempnam-output] is created and that file was guaranteed unique. You'll only get into trouble if you try deleting the tempnam file before you're done with your extended file.

mobius · Accepted Answer · 2012-01-23 12:22:22Z

This might simulate mkstemp() (see http://linux.die.net/man/3/mkstemp) a bit, achieving what you want to do:

function mkstemp( $template ) {
  $attempts = 238328; // 62 x 62 x 62
  $letters  = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  $length   = strlen($letters) - 1;

  if( mb_strlen($template) < 6 || !strstr($template, 'XXXXXX') )
    return FALSE;

  for( $count = 0; $count < $attempts; ++$count) {
    $random = "";

    for($p = 0; $p < 6; $p++) {
      $random .= $letters[mt_rand(0, $length)];
    }

    $randomFile = str_replace("XXXXXX", $random, $template);

    if( !($fd = @fopen($randomFile, "x+")) )
      continue;

    return $fd;
  }

  return FALSE;
}

So you could do:

if( ($f = mkstemp("test-XXXXXX.txt")) ) {
  fwrite($f, "test\n");
  fclose($f);
}

CrimsonNosedAnole · Accepted Answer · 2021-10-08 10:17:02Z

Let's say tempnam() gives you a file of "filename". You move it to "filename.ext". At any point, tempnam() can give you "filename" again. If you check for "filename.ext", reject the filename given by tempnam(), and call it again, you still end up with the possibility that between one step and another, a file will get created with the same name. (This is discussed in the user comments on the documentation page for tempnam(): https://www.php.net/manual/en/function.tempnam.php.)

However, if you just leave the file created by tempnam() alone (not deleting "filename" until you delete "filename.ext") and work with that filename + the extension, then there is no chance that tempnam() will use that filename again (as far as I can see). Yes, it is messy to have "filename" and "filename.ext" for every single file. On the other hand, it solves the problem.

Marco Sulla · Accepted Answer · 2023-01-20 08:41:40Z

2

I prefer this solution:

$uid = uniqid('', true);
$path = sys_get_temp_dir() . "some_prefix_$uid.myextension";

Note: I do not put the prefix in uniqid because, IMHO, it's not its duty

answered Jan 20, 2023 at 8:41

Marco Sulla

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1 Comment

DurandA Over a year ago

An extra / is required beween sys_get_temp_dir() and the filename (at least on my platform).

Jorge · Accepted Answer · 2013-05-06 19:57:41Z

1

public static function makeTempFileInFolder($prefix, $suffix, $folder="")
{
  if (strlen($folder)==0) $folder = sys_get_temp_dir();
  do { 
    $file = $folder."/".$prefix.rand(1,99999).time().$suffix; 
  } while (file_exists($file));
  return $file;
}

answered May 6, 2013 at 19:57

Jorge

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Comments

Alexander Korostin · Accepted Answer · 2020-07-28 02:37:42Z

The same as tempnam() except the additional parameter:

function tempnamp($dir, $prefix, $postfix) {
  $maxAttempts = 1000;
  // Trim trailing slashes from $dir.
  $dir = rtrim($dir, DIRECTORY_SEPARATOR);
  // If we don't have permission to create a directory, fail, otherwise we will
  // be stuck in an endless loop.
  if (!is_dir($dir) || !is_writable($dir)) return false;
  // Make sure characters in prefix and postfix are safe.
  if (strpbrk($prefix, '\\/:*?"<>|') !== false) return false;
  if (strpbrk($postfix, '\\/:*?"<>|') !== false) return false;
  // Attempt to create a random file until it works.
  $attempts = 0;
  do
  {
    $path = $dir.DIRECTORY_SEPARATOR.$prefix.mt_rand(100000, mt_getrandmax()).$postfix;
    $fp = @fopen($path, 'x+');
  } while (!$fp && $attempts++ < $maxAttempts);
  if ($fp) fclose($fp);
  return $path;
}

That 'p' at the end of the name stands for 'postfix'.

zakinster · Accepted Answer · 2013-05-03 14:03:23Z

-1

Maybe using

move_uploaded_file($tmp_name, "$uploads_dir/$name.myextension");

See http://php.net/manual/en/function.move-uploaded-file.php#example-2209

edited May 3, 2013 at 14:03

zakinster

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answered Jan 23, 2012 at 11:35

Lobo

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Comments

lisandro · Accepted Answer · 2021-07-27 10:59:57Z

-1

Rename does it, find the extension with pathinfo and then replace with the extension you want.

$tmpfname = tempnam(sys_get_temp_dir(), 'FOO');
$newname = str_replace(pathinfo($tmpfname, PATHINFO_EXTENSION),'pdf',$tmpfname);
rename($tmpfname, $newname);
//do what you want with $newname
unlink($newname);

answered Jul 27, 2021 at 10:59

lisandro

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