Usage: curl [options...] <url>
--abstract-unix-socket <path> Connect via abstract Unix domain socket
--alt-svc <file name> Enable alt-svc with this cache file
--anyauth Pick any authentication method
-a, --append Append to target file when uploading
--basic Use HTTP Basic Authentication
--cacert <file> CA certificate to verify peer against
--capath <dir> CA directory to verify peer against
-E, --cert <certificate[:password]> Client certificate file and password
--cert-status Verify the status of the server certificate
--cert-type <type> Certificate file type (DER/PEM/ENG)
--ciphers <list of ciphers> SSL ciphers to use
--compressed Request compressed response
--compressed-ssh Enable SSH compression
-K, --config <file> Read config from a file
--connect-timeout <seconds> Maximum time allowed for connection
--connect-to <HOST1:PORT1:HOST2:PORT2> Connect to host
-C, --continue-at <offset> Resumed transfer offset
比如-a 后面有很多个--axxxxx 是表示如果只写-a 就默认是后面刚好正对的那个--append 吗