[C] hide curl_easy_perform

Question

How can I hide curl_easy_perform output (in a shell)?
This is in regards to a C application.

Answer 1

Set the CURLOPT_WRITEFUNCTION and/or CURLOPT_WRITEDATA options:

FILE *f = fopen("target.txt", "wb");
curl_easy_setopt(handle, CURLOPT_WRITEDATA, f);

By default, libcurl writes output to stdout. When you override this (which is what almost any application will do), it will write to another file or to pass chunks of output to a callback. See the documentation for curl_easy_setopt for more details.

Answer 2

As Joey said, CURLOPT_WRITEFUNCTION will allow you to completely disregard all output. Just set up a callback that does absolutely nothing if you want the data to just go away, without being written to any file descriptor.

For instance,

/* Never writes anything, just returns the size presented */
size_t my_dummy_write(void *ptr, size_t size, size_t nmemb, FILE *stream)
{
   return size;
}

Then in your options:

curl_easy_setopt(handle, CURLOPT_WRITEFUNCTION, &my_dummy_write);

Or, point the file handle at a NULL device (a lot easier).