curl/docs/libcurl/opts/CURLOPT_TCP_KEEPIDLE.md
Daniel Stenberg e694c8284a
docs/libcurl/opts: clarify the return values
Expand a little.

- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
  varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes

Closes #15900
2025-01-02 17:13:33 +01:00

1.5 KiB

c SPDX-License-Identifier Title Section Source See-also Protocol Added-in
Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. curl CURLOPT_TCP_KEEPIDLE 3 libcurl
CURLOPT_TCP_KEEPALIVE (3)
CURLOPT_TCP_KEEPINTVL (3)
CURLOPT_TCP_KEEPCNT (3)
TCP
7.25.0

NAME

CURLOPT_TCP_KEEPIDLE - TCP keep-alive idle time wait

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TCP_KEEPIDLE, long delay);

DESCRIPTION

Pass a long. Sets the delay, in seconds, to wait while the connection is idle before sending keepalive probes. Not all operating systems support this option.

The maximum value this accepts is 2147483648. Any larger value is capped to this amount.

DEFAULT

60

%PROTOCOLS%

EXAMPLE

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    /* enable TCP keep-alive for this transfer */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE, 1L);

    /* set keep-alive idle time to 120 seconds */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPIDLE, 120L);

    /* interval time between keep-alive probes: 60 seconds */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPINTVL, 60L);

    /* maximum number of keep-alive probes: 3 */
    curl_easy_setopt(curl, CURLOPT_TCP_KEEPCNT, 3L);

    curl_easy_perform(curl);
  }
}

%AVAILABILITY%

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).