0 Preface/Foreword
1 curl介绍
curl：transfer a URL
synopsis： curl [options] [URL...]
描述：
curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, HTTP, HTTPS, IMAP, FTP, FTPS, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The command is designed to work without user interaction.
curl is powered by libcurl for all transfer-related features.
1.1 --output <file>
--output,和-o，相同的含义。Write output to <file> instead of stdout.
1.2 -L
-L, --location，相同的作用。
(HTTP) If 天河server reports that the requested page has moved to a different location (indicated with a location: header and a 3XX response code), this option will make curl redo the request on the new place.
2 wget介绍
