FTP context options

FTP context option listing

说明

Context options forftp://andftps://transports.

可选项

$overwriteboolean

Allow overwriting of already existing files on remote server. Applies to write mode(uploading)only.

Defaults to FALSE.

$resume_posinteger

File offset at which to begin transfer. Applies to read mode(downloading)only.

Defaults to0(Beginning of File).

$proxystring

Proxy FTP request via http proxy server. Applies to file read operations only. Ex:tcp://squid.example.com:8000.

更新日志

注释

Note:Underlying socket stream context options
Additional context options may be supported by the underlying transport Forftp://streams, refer to context options for thetcp://transport. Forftps://streams, refer to context options for thessl://transport.

参见

• ftp://
• 套接字上下文选项
• SSL 上下文选项

This is an example of how to allow fopen() to overwrite a file on an FTP site. If the stream context is not modified, an error will occur: "...failed to open stream: Remote file already exists and overwrite context option not specified...".
<?php
// The path to the FTP file, including login arguments
$ftp_path = 'ftp://username:password@example.com/example.txt';
// Allows overwriting of existing files on the remote FTP server
$stream_options = array('ftp' => array('overwrite' => true));
// Creates a stream context resource with the defined options
$stream_context = stream_context_create($stream_options);
// Opens the file for writing and truncates it to zero length 
if ($fh = fopen($ftp_path, 'w', 0, $stream_context))
{
  // Writes contents to the file
  fputs($fh, 'example contents');
  
  // Closes the file handle
  fclose($fh);
}
else
{
  die('Could not open file.');
}
?>

Apparently the overwrite-option only registers as false if it's absent. If I specify it as false, it acts the same as true and overwrites. Then, 
<?php
if (empty($opts['overwrite'])) {
  unset($opts['overwrite']);
}
?>
...was the simple fix for my FTP stream wrapper class sporting default options. This is quite unexpected though; false means false even if I say so? Apparently PHP (7.0.2) just checks if the option exists, not its boolean value.