Set a point to resume transfer from
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_RESUME_FROM, long from);
Pass a long as parameter. It contains the offset in number of bytes that you want the transfer to start from. Set this option to 0 to make the transfer start from the beginning (effectively disabling resume). For FTP, set this option to -1 to make the transfer start from the end of the target file (useful to continue an interrupted upload).
When doing uploads with FTP, the resume position is where in the local/source file libcurl should try to resume the upload from and it will then append the source file to the remote target file.
If you need to resume a transfer beyond the 2GB limit, use CURLOPT_RESUME_FROM_LARGE(3) instead.
0, not used
HTTP, FTP, SFTP, FILE