FAQ: Why doesn't cURL error out when the cable is unplugged?

  4.16 My HTTP POST or PUT requests are slow!

  4.17 Non-functional connect timeouts on Windows

  4.18 file:// URLs containing drive letters (Windows, NetWare)

  4.19 Why doesn't cURL return an error when the network cable is unplugged?

 5. libcurl Issues

  5.1 Is libcurl thread-safe?

  In either case, cURL should now be looking for the correct file.

  4.19 Why doesn't cURL return an error when the network cable is unplugged?

  Unplugging the cable is not an error situation. The TCP/IP protocol stack

  was designed to be fault tolerant, so even though there may be a physical

  break somewhere the connection shouldn't be affected, just possibly

  delayed.  Eventually, the physical break will be fixed or the data will be

  re-routed around the physical problem.

  In such cases, the TCP/IP stack is responsible for detecting when the

  network connection is irrevocably lost. Since with some protocols it is

  perfectly legal for the client wait indefinitely for data, the stack may

  never report a problem, and even when it does, it can take up to 20 minutes

  for it to detect an issue.  The curl option --keepalive-time enables

  keep-alive support in the TCP/IP stack which makes it periodically probe the

  connection to make sure it is still available to send data. That should

  reliably detect any TCP/IP network failure.

  But even that won't detect the network going down before the TCP/IP

  connection is established (e.g. during a DNS lookup) or using protocols that

  don't use TCP.  To handle those situations, curl offers a number of timeouts

  on its own. --speed-limit/--speed-time will abort if the data transfer rate

  falls too low, and --connect-timeout and --max-time can be used to put an

  overall timeout on the connection phase or the entire transfer.

5. libcurl Issues

  5.1 Is libcurl thread-safe?

  to do "LIST -a" or similar to see them.

  The application thus needs to parse the LIST output. One such existing

  list parser is available at http://cr.yp.to/ftpparse.html

  list parser is available at http://cr.yp.to/ftpparse.html  Versions of

  libcurl since 7.21.0 also provide the ability to specify a wildcard to

  download multiple files from one FTP directory.

6. License Issues