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Create file with unique file name


(PHP 4, PHP 5)

tempnamCreate file with unique file name


string tempnam ( string $dir , string $prefix )

Creates a file with a unique filename, with access permission set to 0600, in the specified directory. If the directory does not exist, tempnam() may generate a file in the system's temporary directory, and return the name of that.



The directory where the temporary filename will be created.


The prefix of the generated temporary filename.

Note: Windows uses only the first three characters of prefix.

Return Values

Returns the new temporary filename, or FALSE on failure.


Version Description
4.0.6 Prior to PHP 4.0.6, the behaviour of the tempnam() function was system dependent. On Windows the TMP environment variable will override the dir parameter, on Linux the TMPDIR environment variable has precedence, while SVR4 will always use your dir parameter if the directory it points to exists. Consult your system documentation on the tempnam(3) function if in doubt.
4.0.3 This function's behavior changed in 4.0.3. The temporary file is also created to avoid a race condition where the file might appear in the filesystem between the time the string was generated and before the script gets around to creating the file. Note, that you need to remove the file in case you need it no more, it is not done automatically.


Example #1 tempnam() example


$handle fopen($tmpfname"w");
fwrite($handle"writing to tempfile");

// do here something



Note: If PHP cannot create a file in the specified dir parameter, it falls back on the system default. On NTFS this also happens if the specified dir contains more than 65534 files.

See Also

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