function upload($fichier)
{
	$ch = curl_init();
	$fp = fopen($fichier, 'r');
	curl_setopt($ch, CURLOPT_URL, "sftp://11.22.33.44/var/www/html/a.zip");
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
	curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
	curl_setopt($ch, CURLOPT_USERPWD, 'user:pwd111');
	curl_setopt($ch, CURLOPT_UPLOAD, 1);
	curl_setopt($ch, CURLOPT_INFILE, $fp);
	curl_setopt($ch, CURLOPT_INFILESIZE, filesize($fichier));
	$result = curl_exec($ch);
	$error_no = curl_errno($ch);
	curl_close($ch);
	
	if ($error_no == 0) {
		echo('Envoyé');
	} else {
		echo('Erreur : '.$error_no);
	}
}

upload('a.zip');

<?php
    $currentDirectory = getcwd();
    $uploadDirectory = "/uploads/";

    $errors = []; // Store errors here

    $fileExtensionsAllowed = ['zip','rar','tar.gz'];

    $fileName = $_FILES['the_file']['name'];
    $fileSize = $_FILES['the_file']['size'];
    $fileTmpName  = $_FILES['the_file']['tmp_name'];
    $fileType = $_FILES['the_file']['type'];
    $fileExtension = strtolower(end(explode('.',$fileName)));

    $uploadPath = $currentDirectory . $uploadDirectory . basename($fileName); 

    if (isset($_POST['submit'])) {

      if (! in_array($fileExtension,$fileExtensionsAllowed)) {
        $errors[] = "This file extension is not allowed. Please upload a JPEG or PNG file";
      }

      if ($fileSize > 4000000) {
        $errors[] = "File exceeds maximum size (4MB)";
      }

      if (empty($errors)) {
        $didUpload = move_uploaded_file($fileTmpName, $uploadPath);

        if ($didUpload) {
          echo "The file " . basename($fileName) . " has been uploaded";
        } else {
          echo "An error occurred. Please contact the administrator.";
        }
      } else {
        foreach ($errors as $error) {
          echo $error . "These are the errors" . "\n";
        }
      }

    }
?>