CURLOPT_PROXY_TRANSFER_MODE(3)

CURLOPT_PROXY_TRANSFER_MODE3

Append ftp transfer mode to url for proxy

Usage

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_TRANSFER_MODE,
                          long enabled);

Overview

Pass a long. If the value is set to 1 (one), it tells libcurl to set the transfer mode (binary or ASCII) for FTP transfers done via an HTTP proxy, by appending ;type=a or ;type=i to the URL. Without this setting, or it being set to 0 (zero, the default), CURLOPT_TRANSFERTEXT(3) has no effect when doing FTP via a proxy. Beware that not all proxies support this feature.

Default

0, disabled

Protocols

This functionality affects all supported protocols

Examples

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL,
                     "ftp://example.com/old-server/file.txt");
    curl_easy_setopt(curl, CURLOPT_PROXY, "http://localhost:80");
    curl_easy_setopt(curl, CURLOPT_PROXY_TRANSFER_MODE, 1L);
    curl_easy_setopt(curl, CURLOPT_TRANSFERTEXT, 1L);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Return value

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

Releases

7 releases since Debian 8 (Jessie); the text changed 6 times.

  1. 8
  2. 9
  3. 10
  4. 11
  5. 12
  6. 13
  7. Arch

Availability

Added in curl 7.18.0

From curl 8.23.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.