CURLOPT_TIMEOUT_MS (3) - Linux Man Pages
CURLOPT_TIMEOUT_MS: set maximum time the request is allowed to take
NAMECURLOPT_TIMEOUT_MS - set maximum time the request is allowed to take
DESCRIPTIONPass a long as parameter containing timeout - the maximum time in milliseconds that you allow the libcurl transfer operation to take. Normally, name lookups can take a considerable time and limiting operations to less than a few minutes risk aborting perfectly normal operations. This option may cause libcurl to use the SIGALRM signal to timeout system calls.
If libcurl is built to use the standard system name resolver, that portion of the transfer will still use full-second resolution for timeouts with a minimum timeout allowed of one second.
In unix-like systems, this might cause signals to be used unless CURLOPT_NOSIGNAL(3) is set.
Since this puts a hard limit for how long time a request is allowed to take, it has limited use in dynamic use cases with varying transfer times. You are then advised to explore CURLOPT_LOW_SPEED_LIMIT(3), CURLOPT_LOW_SPEED_TIME(3) or using CURLOPT_PROGRESSFUNCTION(3) to implement your own timeout logic.