先来看看帮助文档：
[root@VM-24-15-centos ~]# curl --help Usage: curl [options...] <url> Options: (H) means HTTP/HTTPS only, (F) means FTP only --anyauth Pick "any" authentication method (H) -a, --append Append to target file when uploading (F/SFTP) --basic Use HTTP Basic Authentication (H) --cacert FILE CA certificate to verify peer against (SSL) --capath DIR CA directory to verify peer against (SSL) -E, --cert CERT[:PASSWD] Client certificate file and password (SSL) --cert-type TYPE Certificate file type (DER/PEM/ENG) (SSL) --ciphers LIST SSL ciphers to use (SSL) --compressed Request compressed response (using deflate or gzip) -K, --config FILE Specify which config file to read --connect-timeout SECONDS Maximum time allowed for connection -C, --continue-at OFFSET Resumed transfer offset -b, --cookie STRING/FILE String or file to read cookies from (H) -c, --cookie-jar FILE Write cookies to this file after operation (H) --create-dirs Create necessary local directory hierarchy --crlf Convert LF to CRLF in upload --crlfile FILE Get a CRL list in PEM format from the given file -d, --data DATA HTTP POST data (H) --data-ascii DATA HTTP POST ASCII data (H) --data-binary DATA HTTP POST binary data (H) --data-urlencode DATA HTTP POST data url encoded (H) --delegation STRING GSS-API delegation permission --digest Use HTTP Digest Authentication (H) --disable-eprt Inhibit using EPRT or LPRT (F) --disable-epsv Inhibit using EPSV (F) -D, --dump-header FILE Write the headers to this file --egd-file FILE EGD socket path for random data (SSL) --engine ENGINGE Crypto engine (SSL). "--engine list" for list -f, --fail Fail silently (no output at all) on HTTP errors (H) -F, --form CONTENT Specify HTTP multipart POST data (H) --form-string STRING Specify HTTP multipart POST data (H) --ftp-account DATA Account data string (F) --ftp-alternative-to-user COMMAND String to replace "USER [name]" (F) --ftp-create-dirs Create the remote dirs if not present (F) --ftp-method [MULTICWD/NOCWD/SINGLECWD] Control CWD usage (F) --ftp-pasv Use PASV/EPSV instead of PORT (F) -P, --ftp-port ADR Use PORT with given address instead of PASV (F) --ftp-skip-pasv-ip Skip the IP address for PASV (F) --ftp-pret Send PRET before PASV (for drftpd) (F) --ftp-ssl-ccc Send CCC after authenticating (F) --ftp-ssl-ccc-mode ACTIVE/PASSIVE Set CCC mode (F) --ftp-ssl-control Require SSL/TLS for ftp login, clear for transfer (F) -G, --get Send the -d data with a HTTP GET (H) -g, --globoff Disable URL sequences and ranges using {} and [] -H, --header LINE Custom header to pass to server (H) -I, --head Show document info only -h, --help This help text --hostpubmd5 MD5 Hex encoded MD5 string of the host public key. (SSH) -0, --http1.0 Use HTTP 1.0 (H) --ignore-content-length Ignore the HTTP Content-Length header -i, --include Include protocol headers in the output (H/F) -k, --insecure Allow connections to SSL sites without certs (H) --interface INTERFACE Specify network interface/address to use -4, --ipv4 Resolve name to IPv4 address -6, --ipv6 Resolve name to IPv6 address -j, --junk-session-cookies Ignore session cookies read from file (H) --keepalive-time SECONDS Interval between keepalive probes --key KEY Private key file name (SSL/SSH) --key-type TYPE Private key file type (DER/PEM/ENG) (SSL) --krb LEVEL Enable Kerberos with specified security level (F) --libcurl FILE Dump libcurl equivalent code of this command line --limit-rate RATE Limit transfer speed to this rate -l, --list-only List only names of an FTP directory (F) --local-port RANGE Force use of these local port numbers -L, --location Follow redirects (H) --location-trusted like --location and send auth to other hosts (H) -M, --manual Display the full manual --mail-from FROM Mail from this address --mail-rcpt TO Mail to this receiver(s) --mail-auth AUTH Originator address of the original email --max-filesize BYTES Maximum file size to download (H/F) --max-redirs NUM Maximum number of redirects allowed (H) -m, --max-time SECONDS Maximum time allowed for the transfer --metalink Process given URLs as metalink XML file --negotiate Use HTTP Negotiate Authentication (H) -n, --netrc Must read .netrc for user name and password --netrc-optional Use either .netrc or URL; overrides -n --netrc-file FILE Set up the netrc filename to use -N, --no-buffer Disable buffering of the output stream --no-keepalive Disable keepalive use on the connection --no-sessionid Disable SSL session-ID reusing (SSL) --noproxy List of hosts which do not use proxy --ntlm Use HTTP NTLM authentication (H) -o, --output FILE Write output to <file> instead of stdout --pass PASS Pass phrase for the private key (SSL/SSH) --post301 Do not switch to GET after following a 301 redirect (H) --post302 Do not switch to GET after following a 302 redirect (H) --post303 Do not switch to GET after following a 303 redirect (H) -#, --progress-bar Display transfer progress as a progress bar --proto PROTOCOLS Enable/disable specified protocols --proto-redir PROTOCOLS Enable/disable specified protocols on redirect -x, --proxy [PROTOCOL://]HOST[:PORT] Use proxy on given port --proxy-anyauth Pick "any" proxy authentication method (H) --proxy-basic Use Basic authentication on the proxy (H) --proxy-digest Use Digest authentication on the proxy (H) --proxy-negotiate Use Negotiate authentication on the proxy (H) --proxy-ntlm Use NTLM authentication on the proxy (H) -U, --proxy-user USER[:PASSWORD] Proxy user and password --proxy1.0 HOST[:PORT] Use HTTP/1.0 proxy on given port -p, --proxytunnel Operate through a HTTP proxy tunnel (using CONNECT) --pubkey KEY Public key file name (SSH) -Q, --quote CMD Send command(s) to server before transfer (F/SFTP) --random-file FILE File for reading random data from (SSL) -r, --range RANGE Retrieve only the bytes within a range --raw Do HTTP "raw", without any transfer decoding (H) -e, --referer Referer URL (H) -J, --remote-header-name Use the header-provided filename (H) -O, --remote-name Write output to a file named as the remote file --remote-name-all Use the remote file name for all URLs -R, --remote-time Set the remote file's time on the local output -X, --request COMMAND Specify request command to use --resolve HOST:PORT:ADDRESS Force resolve of HOST:PORT to ADDRESS --retry NUM Retry request NUM times if transient problems occur --retry-delay SECONDS When retrying, wait this many seconds between each --retry-max-time SECONDS Retry only within this period -S, --show-error Show error. With -s, make curl show errors when they occur -s, --silent Silent mode. Don't output anything --socks4 HOST[:PORT] SOCKS4 proxy on given host + port --socks4a HOST[:PORT] SOCKS4a proxy on given host + port --socks5 HOST[:PORT] SOCKS5 proxy on given host + port --socks5-basic Enable username/password auth for SOCKS5 proxies --socks5-gssapi Enable GSS-API auth for SOCKS5 proxies --socks5-hostname HOST[:PORT] SOCKS5 proxy, pass host name to proxy --socks5-gssapi-service NAME SOCKS5 proxy service name for gssapi --socks5-gssapi-nec Compatibility with NEC SOCKS5 server -Y, --speed-limit RATE Stop transfers below speed-limit for 'speed-time' secs -y, --speed-time SECONDS Time for trig speed-limit abort. Defaults to 30 --ssl Try SSL/TLS (FTP, IMAP, POP3, SMTP) --ssl-reqd Require SSL/TLS (FTP, IMAP, POP3, SMTP) -2, --sslv2 Use SSLv2 (SSL) -3, --sslv3 Use SSLv3 (SSL) --ssl-allow-beast Allow security flaw to improve interop (SSL) --stderr FILE Where to redirect stderr. - means stdout --tcp-nodelay Use the TCP_NODELAY option -t, --telnet-option OPT=VAL Set telnet option --tftp-blksize VALUE Set TFTP BLKSIZE option (must be >512) -z, --time-cond TIME Transfer based on a time condition -1, --tlsv1 Use => TLSv1 (SSL) --tlsv1.0 Use TLSv1.0 (SSL) --tlsv1.1 Use TLSv1.1 (SSL) --tlsv1.2 Use TLSv1.2 (SSL) --tlsv1.3 Use TLSv1.3 (SSL) --tls-max VERSION Use TLS up to VERSION (SSL) --trace FILE Write a debug trace to the given file --trace-ascii FILE Like --trace but without the hex output --trace-time Add time stamps to trace/verbose output --tr-encoding Request compressed transfer encoding (H) -T, --upload-file FILE Transfer FILE to destination --url URL URL to work with -B, --use-ascii Use ASCII/text transfer -u, --user USER[:PASSWORD] Server user and password --tlsuser USER TLS username --tlspassword STRING TLS password --tlsauthtype STRING TLS authentication type (default SRP) --unix-socket FILE Connect through this UNIX domain socket -A, --user-agent STRING User-Agent to send to server (H) -v, --verbose Make the operation more talkative -V, --version Show version number and quit -w, --write-out FORMAT What to output after completion --xattr Store metadata in extended file attributes -q If used as the first parameter disables .curlrc
我们看常用的：
#这里我们设置超时时间为2s, 请求一个无法解析的地址 [root@VM-24-15-centos ~]# curl --connect-timeout 2 --url http://xxx.com curl: (7) Failed connect to xxx.com:80; Operation now in progress # 一个是可以通的 [root@VM-24-15-centos ~]# curl --connect-timeout 2 --url http://www.baidu.com <!DOCTYPE html> <!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class=head_wrapper> <div class=s_form> <div class=s_form_wrapper> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class=fm> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class=s_ipt value maxlength=255 autocomplete=off autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn"></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class=mnav>新闻</a> <a href=http://www.hao123.com name=tj_trhao123 class=mnav>hao123</a> <a href=http://map.baidu.com name=tj_trmap class=mnav>地图</a> <a href=http://v.baidu.com name=tj_trvideo class=mnav>视频</a> <a href=http://tieba.baidu.com name=tj_trtieba class=mnav>贴吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class=lb>登录</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登录</a>');</script> <a href=//www.baidu.com/more/ name=tj_briicon class=bri style="display: block;">更多产品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>关于百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>©2017 Baidu <a href=http://www.baidu.com/duty/>使用百度前必读</a> <a href=http://jianyi.baidu.com/ class=cp-feedback>意见反馈</a> 京ICP证030173号 <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html> [root@VM-24-15-centos ~]#
重试延迟 retry-delay
我们在 请求重试 里面讲到, 这里的重试并不是失败后立刻重试的, 默认重试时间递增, 这里我们可以使用 retry-delay 控制重试的间隔.
#这里我们设置重试时间5s,重试3次 curl --retry 3 --retry-delay 5 --max-time 0.1 --url http://xxx.com > Warning: Transient problem: timeout Will retry in 5 seconds. 3 retries left. > Warning: Transient problem: timeout Will retry in 5 seconds. 2 retries left. > Warning: Transient problem: timeout Will retry in 5 seconds. 1 retries left. > curl: (28) Connection timed out after 101 milliseconds
