CURLOPT_USERAGENT(3) Library Functions Manual CURLOPT_USERAGENT(3)

CURLOPT_USERAGENT - HTTP user-agent header

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_USERAGENT, char *ua);

Pass a pointer to a null-terminated string as parameter. It is used to set the User-Agent: header field in the HTTP request sent to the remote server. You can also set any custom header with CURLOPT_HTTPHEADER(3).

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

Using this option multiple times makes the last set string override the previous ones. Set it to NULL to disable its use again.

NULL, no User-Agent: header is used.

This functionality affects http only

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    curl_easy_setopt(curl, CURLOPT_USERAGENT, "Dark Secret Ninja/1.0");
    curl_easy_perform(curl);
  }
}

Added in curl 7.1

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).

CURLOPT_CUSTOMREQUEST(3), CURLOPT_HTTPHEADER(3), CURLOPT_REFERER(3), CURLOPT_REQUEST_TARGET(3)

2025-02-08 libcurl