CURLOPT_TIMECONDITION − select condition for a time request
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TIMECONDITION, long cond);
Pass a long as parameter. This defines how the CURLOPT_TIMEVALUE(3) time value is treated. You can set this parameter to CURL_TIMECOND_IFMODSINCE or CURL_TIMECOND_IFUNMODSINCE.
The last modification time of a file is not always known and in such instances this feature will have no effect even if the given time condition would not have been met. curl_easy_getinfo(3) with the CURLINFO_CONDITION_UNMET option can be used after a transfer to learn if a zero-byte successful "transfer" was due to this condition not matching.
HTTP, FTP, RTSP, and FILE
CURL *curl =
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* January 1,
2020 is 1577833200 */
curl_easy_setopt(curl, CURLOPT_TIMEVALUE, 1577833200L);
If-Modified-Since the above time stamp */
curl_easy_setopt(curl, CURLOPT_TIMECONDITION, CURL_TIMECOND_IFMODSINCE);
/* Perform the