If running on a Linux system where systemd has PrivateTmp=true (which is the default on CentOS 7 and perhaps other newer distros), this function will simply return "/tmp", not the true, much longer, somewhat dynamic path.
(PHP 5 >= 5.2.1, PHP 7, PHP 8)
sys_get_temp_dir — Returns directory path used for temporary files
Returns the path of the directory PHP stores temporary files in by default.
This function has no parameters.
Returns the path of the temporary directory.
Example #1 sys_get_temp_dir() example
<?php
// Create a temporary file in the temporary
// files directory using sys_get_temp_dir()
$temp_file = tempnam(sys_get_temp_dir(), 'Tux');
echo $temp_file;
?>The above example will output something similar to:
C:\Windows\Temp\TuxA318.tmp
If running on a Linux system where systemd has PrivateTmp=true (which is the default on CentOS 7 and perhaps other newer distros), this function will simply return "/tmp", not the true, much longer, somewhat dynamic path.As of PHP 5.5.0, you can set the sys_temp_dir INI setting so that this function will return a useful value when the default temporary directory is not an option.This function does not always add trailing slash. This behaviour is inconsistent across systems, so you have keep an eye on it.It's not documented but this function does not send the path with trailing spaces, actually it drops the slash if it exists.
https://github.com/php/php-src/blob/af6c11c5f060870d052a2b765dc634d9e47d0f18/main/php_open_temporary_file.c#L238it should be mentioned that the return value of sys_get_temp_dir() can be set using the ini-directive 'sys_temp_dir' globally as well as per directory by using
php_admin_value sys_temp_dir /path/to/tmpA very helpful thing to note when on Linux:
If you are running PHP from the commandline you can use the environment variable: TMPDIR - to change the location without touching php.ini. - This should work on most versions of PHP.
Example file: test.php
<?php
echo sys_get_temp_dir() . PHP_EOL;
?>
And then running:
php test.php
/tmp
TMPDIR=/custom/location php test.php
/custom/locationThat is important for the purposes of building paths through concatenation to know that sys_get_temp_dir does not include a path separator at the end.
So, sys_get_temp_dir() will return whatever your temp dir is set to, by default:
/tmp
If you attempted to concatenate another dir name temp and use the following:
mkdir(sys_get_temp_dir() . 'some_dir');
That would actually attempt to generate:
/tmpsome_dir
It would likely result in a permission error unless you are running a php script as a super user.
Instead you would want to do:
mkdir( sys_get_temp_dir() . DIRECTORY_SEPARATOR. 'some_dir' );
which would create:
/tmp/some_dir
I don't know if Windows or other platforms include a directory separator at the end. So if you are writing something a bit more general you may want to check for the path separator at the end and if it is not there append it.This function does not account for virtualhost-specific modifications to the temp path and/or open_basedir:
<Virtualhost>
php_admin_value open_basedir /home/user
php_admin_value upload_tmp_dir /home/user/tmp
php_admin_value session.save_path /home/user/tmp
</Virtualhost>
Within this config it still returns /tmpwhen the sys_temp_dir directive is left unset, sys_get_temp_dir() returns C:\Windows on my Windows.