CURLOPT_INFILESIZE (3) - Linux Man Pages
CURLOPT_INFILESIZE: set size of the input file to send off
NAMECURLOPT_INFILESIZE - set size of the input file to send off
DESCRIPTIONWhen uploading a file to a remote site, filesize should be used to tell libcurl what the expected size of the input file is. This value must be passed as a long. See also CURLOPT_INFILESIZE_LARGE(3) for sending files larger than 2GB.
For uploading using SCP, this option or CURLOPT_INFILESIZE_LARGE(3) is mandatory.
To unset this value again, set it to -1.
When sending emails using SMTP, this command can be used to specify the optional SIZE parameter for the MAIL FROM command.
This option does not limit how much data libcurl will actually send, as that is controlled entirely by what the read callback returns, but telling one value and sending a different amount may lead to errors.