Create a folder if it doesn't already exist

Try this, using mkdir:

if (!file_exists('path/to/directory')) {
    mkdir('path/to/directory', 0777, true);
}

Note that 0777 is already the default mode for directories and may still be modified by the current umask.

---

Here is the missing piece. You need to pass 'recursive' flag as third argument (boolean true) in mkdir call like this:

mkdir('path/to/directory', 0755, true);

---

Here is something a bit more universal since this comes up on Google. While the details are more specific, the title of this question is more universal.

/**
 * recursively create a long directory path
 */
function createPath($path) {
    if (is_dir($path)) 
        return true;
    $prev_path = substr($path, 0, strrpos($path, '/', -2) + 1 );
    $return = createPath($prev_path);
    return ($return && is_writable($prev_path)) ? mkdir($path) : false;
}

This will take a path, possibly with a long chain of uncreated directories, and keep going up one directory until it gets to an existing directory. Then it will attempt to create the next directory in that directory, and continue till it's created all the directories. It returns true if successful.

It could be improved by providing a stopping level so it just fails if it goes beyond the user folder or something and by including permissions.

---

Use a helper function like this:

function makeDir($path)
{
     $ret = mkdir($path); // use @mkdir if you want to suppress warnings/errors
     return $ret === true || is_dir($path);
}

It will return true if the directory was successfully created or already exists, and false if the directory couldn't be created.

A better alternative is this (shouldn't give any warnings):

function makeDir($path)
{
     return is_dir($path) || mkdir($path);
}

---

A faster way to create a folder:

if (!is_dir('path/to/directory')) {
    mkdir('path/to/directory', 0777, true);
}

---

Recursively create the directory path:

function makedirs($dirpath, $mode=0777) {
    return is_dir($dirpath) || mkdir($dirpath, $mode, true);
}

Inspired by Python's os.makedirs()

---

The best way is to use the wp_mkdir_p function. This function will recursively create a folder with the correct permissions.

Also, you can skip folder exists condition because the function returns:

true when the directory was created or existed before

false if you can't create the directory.

Example:

$path = 'path/to/directory';
if ( wp_mkdir_p( $path ) ) {
    // Directory exists or was created.
}

More: https://developer.wordpress.org/reference/functions/wp_mkdir_p/

---

Within WordPress, there's also the very handy function wp_mkdir_p which will recursively create a directory structure.

Source for reference:

function wp_mkdir_p( $target ) {
    $wrapper = null;

    // Strip the protocol
    if( wp_is_stream( $target ) ) {
        list( $wrapper, $target ) = explode( '://', $target, 2 );
    }

    // From php.net/mkdir user contributed notes
    $target = str_replace( '//', '/', $target );

    // Put the wrapper back on the target
    if( $wrapper !== null ) {
        $target = $wrapper . '://' . $target;
    }

    // Safe mode fails with a trailing slash under certain PHP versions.
    $target = rtrim($target, '/'); // Use rtrim() instead of untrailingslashit to avoid formatting.php dependency.
    if ( empty($target) )
        $target = '/';

    if ( file_exists( $target ) )
        return @is_dir( $target );

    // We need to find the permissions of the parent folder that exists and inherit that.
    $target_parent = dirname( $target );
    while ( '.' != $target_parent && ! is_dir( $target_parent ) ) {
        $target_parent = dirname( $target_parent );
    }

    // Get the permission bits.
    if ( $stat = @stat( $target_parent ) ) {
        $dir_perms = $stat['mode'] & 0007777;
    } else {
        $dir_perms = 0777;
    }

    if ( @mkdir( $target, $dir_perms, true ) ) {

        // If a umask is set that modifies $dir_perms, we'll have to re-set the $dir_perms correctly with chmod()
        if ( $dir_perms != ( $dir_perms & ~umask() ) ) {
            $folder_parts = explode( '/', substr( $target, strlen( $target_parent ) + 1 ) );
            for ( $i = 1; $i <= count( $folder_parts ); $i++ ) {
                @chmod( $target_parent . '/' . implode( '/', array_slice( $folder_parts, 0, $i ) ), $dir_perms );
            }
        }

        return true;
    }

    return false;
}

---

I needed the same thing for a login site. I needed to create a directory with two variables.

The $directory is the main folder where I wanted to create another sub-folder with the users license number.

include_once("../include/session.php");

$lnum = $session->lnum; // Users license number from sessions
$directory = uploaded_labels; // Name of directory that folder is being created in

if (!file_exists($directory . "/" . $lnum)) {
    mkdir($directory . "/" . $lnum, 0777, true);
}

---

This is the most up-to-date solution without error suppression:

if (!is_dir('path/to/directory')) {
    mkdir('path/to/directory');
}

---

For your specific question about WordPress, use the following code:

if (!is_dir(ABSPATH . 'wp-content/uploads')) wp_mkdir_p(ABSPATH . 'wp-content/uploads');

Function Reference: WordPress wp_mkdir_p. ABSPATH is the constant that returns WordPress working directory path.

There is another WordPress function named wp_upload_dir(). It returns the upload directory path and creates a folder if doesn't already exists.

$upload_path = wp_upload_dir();

The following code is for PHP in general.

if (!is_dir('path/to/directory')) mkdir('path/to/directory', 0777, true);

Function reference: PHP is_dir()

---

$upload = wp_upload_dir();
$upload_dir = $upload['basedir'];
$upload_dir = $upload_dir . '/newfolder';
if (! is_dir($upload_dir)) {
   mkdir( $upload_dir, 0700 );
}

---

If you want to avoid the file_exists vs. is_dir problem, I would suggest you to look here.

I tried this and it only creates the directory if the directory does not exist. It does not care if there is a file with that name.

/* Creates the directory if it does not exist */
$path_to_directory = 'path/to/directory';
if (!file_exists($path_to_directory) && !is_dir($path_to_directory)) {
    mkdir($path_to_directory, 0777, true);
}

---

To create a folder if it doesn't already exist

Considering the question's environment.

WordPress.

Webhosting server.

Assuming it's Linux, not Windows running PHP.

And quoting from: mkdir

bool mkdir ( string $pathname [, int $mode = 0777 [, bool $recursive = FALSE [, resource $context ]]] )

The manual says that the only required parameter is the $pathname!

So, we can simply code:

<?php
    error_reporting(0); 

    if(!mkdir('wp-content/uploads')){
        // Todo
    }
?>

Explanation:

We don't have to pass any parameter or check if the folder exists or even pass the mode parameter unless needed; for the following reasons:

The command will create the folder with 0755 permission (the shared hosting folder's default permission) or 0777, the command's default.

mode is ignored on Windows hosting running PHP.

Already the mkdir command has a built-in checker for if the folder exists; so we need to check the return only True|False ; and it’s not an error; it’s a warning only, and Warning is disabled on the hosting servers by default.

As per speed, this is faster if warning disabled.

This is just another way to look into the question and not claiming a better or most optimal solution.

It was tested on PHP 7, production server, and Linux

---

if (!is_dir('path_directory')) {
    @mkdir('path_directory');
}

---

Here you go.

if (!is_dir('path/to/directory')) {
    if (!mkdir('path/to/directory', 0777, true) && !is_dir('path/to/directory')) {
        throw new \RuntimeException(sprintf('Directory "%s" was not created', 'path/to/directory'));
    }
}

---

You can try also:

$dirpath = "path/to/dir";
$mode = "0764";
is_dir($dirpath) || mkdir($dirpath, $mode, true);

---

As a complement to current solutions, a utility function.

function createDir($path, $mode = 0777, $recursive = true) {
  if(file_exists($path)) return true;
  return mkdir($path, $mode, $recursive);
}

createDir('path/to/directory');

It returns true if already exists or successfully created. Else it returns false.

---

We should always modularise our code and I've written the same check it below...

We first check the directory. If the directory is absent, we create the directory.

$boolDirPresents = $this->CheckDir($DirectoryName);

if (!$boolDirPresents) {
        $boolCreateDirectory = $this->CreateDirectory($DirectoryName);
        if ($boolCreateDirectory) {
        echo "Created successfully";
      }
  }

function CheckDir($DirName) {
    if (file_exists($DirName)) {
        echo "Dir Exists<br>";
        return true;
    } else {
        echo "Dir Not Absent<br>";
        return false;
    }
}
     
function CreateDirectory($DirName) {
    if (mkdir($DirName, 0777)) {
        return true;
    } else {
        return false;
    }
}

---

You first need to check if directory exists file_exists('path_to_directory')

Then use mkdir(path_to_directory) to create a directory

mkdir( string $pathname [, int $mode = 0777 [, bool $recursive = FALSE [, resource $context ]]] ) : bool

More about mkdir() here

Full code here:

$structure = './depth1/depth2/depth3/';
if (!file_exists($structure)) {
    mkdir($structure);
}

---