file_put_contents 是最简单的解决方案：

  file_put_contents（'ftp：// username：pa ssword @ hostname / path / to / file'，$ contents）; 
 

如果不起作用，可能是因为您没有在PHP中启用URL封装器。

---

如果您需要更好地控制写入（传输模式，被动模式，偏移量，读取限制等），请使用 ftp_fput 与 php：// temp （或 php：// memory ）流：

  $ conn_id = ftp_connect（'hostname'）; 

 ftp_login（$ conn_id，'username'，'password'）; 

 $ h = fopen（'php：// temp'，'r +'）; 
 fwrite（$ h，$ contents）; 
倒带（$ h）; 

 ftp_fput（$ conn_id，'/ path / to / file'，$ h，FTP_BINARY，0）; 

 fclose（$ h）; 
 ftp_close（$ conn_id）; 
 

（添加错误处理）

I am having some JSON data that I encoded it with PHP's json_encode(), it looks like this:

{
    "site": "site1",
    "nbrSicEnt": 85,
}

What I want to do is to write the data directly as a file onto an FTP server.

For security reasons, I don't want the file to be created locally first before sending it to the FTP server, I want it to be created on the fly. So without using tmpfile() for example.

When I read the php documentations for ftp_put:

bool ftp_put ( resource $ftp_stream , string $remote_file , 
               string $local_file , int $mode [, int $startpos = 0 ] )

Ones needs to create a local file (string $local_file) before writing it to the remote file.

I am looking for a way to directly write into the remote_file. How can I do that using PHP?

The file_put_contents is the easiest solution:

file_put_contents('ftp://username:pa‌​ssword@hostname/path/to/file', $contents);

If it does not work, it's probably because you do not have URL wrappers enabled in PHP.

---

If you need greater control over the writting (transfer mode, passive mode, offset, reading limit, etc), use the ftp_fput with a handle to the php://temp (or the php://memory) stream:

$conn_id = ftp_connect('hostname');

ftp_login($conn_id, 'username', 'password');

$h = fopen('php://temp', 'r+');
fwrite($h, $contents);
rewind($h);

ftp_fput($conn_id, '/path/to/file', $h, FTP_BINARY, 0);

fclose($h);
ftp_close($conn_id);

(add error handling)