---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_UNIX_SOCKET_PATH
Section: 3
Source: libcurl
See-also:
  - CURLOPT_ABSTRACT_UNIX_SOCKET (3)
  - CURLOPT_OPENSOCKETFUNCTION (3)
  - unix (7)
---

# NAME

CURLOPT_UNIX_SOCKET_PATH - Unix domain socket

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_UNIX_SOCKET_PATH, char *path);
~~~

# DESCRIPTION

Enables the use of Unix domain sockets as connection endpoint and sets the
path to *path*. If *path* is NULL, then Unix domain sockets are
disabled.

When enabled, curl connects to the Unix domain socket instead of establishing
a TCP connection to the host. Since no network connection is created, curl
does not resolve the DNS hostname in the URL.

The maximum path length on Cygwin, Linux and Solaris is 107. On other platforms
it might be even less.

Proxy and TCP options such as CURLOPT_TCP_NODELAY(3) are not
supported. Proxy options such as CURLOPT_PROXY(3) have no effect either
as these are TCP-oriented, and asking a proxy server to connect to a certain
Unix domain socket is not possible.

The application does not have to keep the string around after setting this
option.

# DEFAULT

Default is NULL, meaning that no Unix domain sockets are used.

# PROTOCOLS

All protocols except for FILE and FTP are supported in theory. HTTP, IMAP,
POP3 and SMTP should in particular work (including their SSL/TLS variants).

# EXAMPLE

~~~c
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_UNIX_SOCKET_PATH, "/tmp/httpd.sock");
    curl_easy_setopt(curl, CURLOPT_URL, "http://localhost/");

    curl_easy_perform(curl);
  }
}
~~~

If you are on Linux and somehow have a need for paths larger than 107 bytes,
you can use the proc filesystem to bypass the limitation:

~~~c
  int dirfd = open(long_directory_path_to_socket, O_DIRECTORY | O_RDONLY);
  char path[108];
  snprintf(path, sizeof(path), "/proc/self/fd/%d/httpd.sock", dirfd);
  curl_easy_setopt(curl_handle, CURLOPT_UNIX_SOCKET_PATH, path);
  /* Be sure to keep dirfd valid until you discard the handle */
~~~

# AVAILABILITY

Added in 7.40.0.

# RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
