CURL 小结

Jul 10, 2021 Eric Guo    706

摘要：总结一下常用操作

url 是一种命令行工具，作用是发出网络请求，然后获取数据，显示在"标准输出"（stdout）上面。它支持多种协议，下面列举其常用功能。

一、查看网页源码

直接在 curl 命令后加上网址，就可以看到网页源码。以网址 www.sina.com为例（选择该网址，主要因为它的网页代码较短）。

  1. $ curl www.sina.com
  2. <html>
  3. <head><title>301 Moved Permanently</title></head>
  4. <body bgcolor="white">
  5. <center><h1>301 Moved Permanently</h1></center>
  6. <hr><center>nginx</center>
  7. </body>
  8. </html>
  9.

如果要把这个网页保存下来，可以使用 -o 参数：

$ curl -o [文件名] www.sina.com

二、自动跳转

有的网址是自动跳转的。使用 -L 参数，curl 就会跳转到新的网址。

$ curl -L www.sina.com

键入上面的命令，结果自动跳转为 www.sina.com.cn。

三、显示头信息

-i 参数可以显示 http response 的头信息，连同网页代码一起。-I 参数则只显示 http response 的头信息。

  1. $ curl -i www.sina.com
  2. HTTP/1.1 301 Moved Permanently
  3. Server: nginx
  4. Date: Tue, 23 Aug 2016 08:30:16 GMT
  5. Content-Type: text/html
  6. Location: http://www.sina.com.cn/
  7. Expires: Tue, 23 Aug 2016 08:32:16 GMT
  8. Cache-Control: max-age=120
  9. Age: 102
  10. Content-Length: 178
  11. X-Cache: HIT from xd33-83.sina.com.cn
  12.  
  13. <html>
  14. <head><title>301 Moved Permanently</title></head>
  15. <body bgcolor="white">
  16. <center><h1>301 Moved Permanently</h1></center>
  17. <hr><center>nginx</center>
  18. </body>
  19. </html>

四、显示通信过程

-v 参数可以显示一次 http 通信的整个过程，包括端口连接和 http request 头信息。

  1. $ curl -v www.sina.com
  2. * Rebuilt URL to: www.sina.com/
  3. * Hostname was NOT found in DNS cache
  4. *   Trying 202.108.33.60...
  5. * Connected to www.sina.com (202.108.33.60) port 80 (#0)
  6. > GET / HTTP/1.1
  7. > User-Agent: curl/7.35.0
  8. > Host: www.sina.com
  9. > Accept: */*
  10. > 
  11. < HTTP/1.1 301 Moved Permanently
  12. * Server nginx is not blacklisted
  13. < Server: nginx
  14. < Date: Tue, 23 Aug 2016 08:48:14 GMT
  15. < Content-Type: text/html
  16. < Location: http://www.sina.com.cn/
  17. < Expires: Tue, 23 Aug 2016 08:50:14 GMT
  18. < Cache-Control: max-age=120
  19. < Age: 40
  20. < Content-Length: 178
  21. < X-Cache: HIT from xd33-81.sina.com.cn
  22. < 
  23. <html>
  24. <head><title>301 Moved Permanently</title></head>
  25. <body bgcolor="white">
  26. <center><h1>301 Moved Permanently</h1></center>
  27. <hr><center>nginx</center>
  28. </body>
  29. </html>
  30. * Connection #0 to host www.sina.com left intact

如果觉得上面的信息还不够，那么下面的命令可以查看更详细的通信过程。

$ curl --trace output.txt www.sina.com

或者

$ curl --trace-ascii output.txt www.sina.com

运行后，打开 output.txt 文件查看。

五、发送表单信息

发送表单信息有 GET 和 POST 两种方法。GET 方法相对简单，只要把数据附在网址后面就行。

$ curl example.com/form.cgi?data=xxx

POST 方法必须把数据和网址分开，curl 就要用到 --data 或者 -d 参数。

$ curl -X POST --data "data=xxx" example.com/form.cgi

如果你的数据没有经过表单编码，还可以让 curl 为你编码，参数是 --data-urlencode。

$ curl -X POST--data-urlencode "date=April 1" example.com/form.cgi

六、HTTP动词

curl 默认的 HTTP 动词是 GET，使用 -X 参数可以支持其他动词。

  1. $ curl -X POST www.example.com
  2. $ curl -X DELETE www.example.com

七、User Agent字段

这个字段是用来表示客户端的设备信息。服务器有时会根据这个字段，针对不同设备，返回不同格式的网页，比如手机版和桌面版。浏览器的 User Agent 是：

Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.84 Safari/537.36

curl 可以这样模拟：

$ curl --user-agent "[User Agent]" [URL]

八、cookie

使用 --cookie 参数，可以让 curl 发送 cookie。

$ curl --cookie "name=xxx" www.example.com

至于具体的 cookie 的值，可以从 http response 头信息的 Set-Cookie 字段中得到。

九、增加头信息--header 

有时需要在 http request 之中，自行增加一个头信息。--header 参数就可以起到这个作用。

$ curl --header "Content-Type:application/json" http://example.com

十、HTTP认证

有些网域需要 HTTP 认证，这时 curl 需要用到 --user 或者 -u 参数。

$ curl --user name:password example.com

附录 curl 命令完整的参数

  1. $ curl --help
  2. Usage: curl [options...] <url>
  3. Options: (H) means HTTP/HTTPS only, (F) means FTP only
  4.      --anyauth       Pick "any" authentication method (H)
  5.  -a, --append        Append to target file when uploading (F/SFTP)
  6.      --basic         Use HTTP Basic Authentication (H)
  7.      --cacert FILE   CA certificate to verify peer against (SSL)
  8.      --capath DIR    CA directory to verify peer against (SSL)
  9.  -E, --cert CERT[:PASSWD] Client certificate file and password (SSL)
  10.      --cert-type TYPE Certificate file type (DER/PEM/ENG) (SSL)
  11.      --ciphers LIST  SSL ciphers to use (SSL)
  12.      --compressed    Request compressed response (using deflate or gzip)
  13.  -K, --config FILE   Specify which config file to read
  14.      --connect-timeout SECONDS  Maximum time allowed for connection
  15.  -C, --continue-at OFFSET  Resumed transfer offset
  16.  -b, --cookie STRING/FILE  String or file to read cookies from (H)
  17.  -c, --cookie-jar FILE  Write cookies to this file after operation (H)
  18.      --create-dirs   Create necessary local directory hierarchy
  19.      --crlf          Convert LF to CRLF in upload
  20.      --crlfile FILE  Get a CRL list in PEM format from the given file
  21.  -d, --data DATA     HTTP POST data (H)
  22.      --data-ascii DATA  HTTP POST ASCII data (H)
  23.      --data-binary DATA  HTTP POST binary data (H)
  24.      --data-urlencode DATA  HTTP POST data url encoded (H)
  25.      --delegation STRING GSS-API delegation permission
  26.      --digest        Use HTTP Digest Authentication (H)
  27.      --disable-eprt  Inhibit using EPRT or LPRT (F)
  28.      --disable-epsv  Inhibit using EPSV (F)
  29.      --dns-servers    DNS server addrs to use: 1.1.1.1;2.2.2.2
  30.      --dns-interface  Interface to use for DNS requests
  31.      --dns-ipv4-addr  IPv4 address to use for DNS requests, dot notation
  32.      --dns-ipv6-addr  IPv6 address to use for DNS requests, dot notation
  33.  -D, --dump-header FILE  Write the headers to this file
  34.      --egd-file FILE  EGD socket path for random data (SSL)
  35.      --engine ENGINE  Crypto engine (SSL). "--engine list" for list
  36.  -f, --fail          Fail silently (no output at all) on HTTP errors (H)
  37.  -F, --form CONTENT  Specify HTTP multipart POST data (H)
  38.      --form-string STRING  Specify HTTP multipart POST data (H)
  39.      --ftp-account DATA  Account data string (F)
  40.      --ftp-alternative-to-user COMMAND  String to replace "USER [name]" (F)
  41.      --ftp-create-dirs  Create the remote dirs if not present (F)
  42.      --ftp-method [MULTICWD/NOCWD/SINGLECWD] Control CWD usage (F)
  43.      --ftp-pasv      Use PASV/EPSV instead of PORT (F)
  44.  -P, --ftp-port ADR  Use PORT with given address instead of PASV (F)
  45.      --ftp-skip-pasv-ip Skip the IP address for PASV (F)
  46.      --ftp-pret      Send PRET before PASV (for drftpd) (F)
  47.      --ftp-ssl-ccc   Send CCC after authenticating (F)
  48.      --ftp-ssl-ccc-mode ACTIVE/PASSIVE  Set CCC mode (F)
  49.      --ftp-ssl-control Require SSL/TLS for ftp login, clear for transfer (F)
  50.  -G, --get           Send the -d data with a HTTP GET (H)
  51.  -g, --globoff       Disable URL sequences and ranges using {} and []
  52.  -H, --header LINE   Custom header to pass to server (H)
  53.  -I, --head          Show document info only
  54.  -h, --help          This help text
  55.      --hostpubmd5 MD5  Hex encoded MD5 string of the host public key. (SSH)
  56.  -0, --http1.0       Use HTTP 1.0 (H)
  57.      --http1.1       Use HTTP 1.1 (H)
  58.      --http2.0       Use HTTP 2.0 (H)
  59.      --ignore-content-length  Ignore the HTTP Content-Length header
  60.  -i, --include       Include protocol headers in the output (H/F)
  61.  -k, --insecure      Allow connections to SSL sites without certs (H)
  62.      --interface INTERFACE  Specify network interface/address to use
  63.  -4, --ipv4          Resolve name to IPv4 address
  64.  -6, --ipv6          Resolve name to IPv6 address
  65.  -j, --junk-session-cookies Ignore session cookies read from file (H)
  66.      --keepalive-time SECONDS  Interval between keepalive probes
  67.      --key KEY       Private key file name (SSL/SSH)
  68.      --key-type TYPE Private key file type (DER/PEM/ENG) (SSL)
  69.      --krb LEVEL     Enable Kerberos with specified security level (F)
  70.      --libcurl FILE  Dump libcurl equivalent code of this command line
  71.      --limit-rate RATE  Limit transfer speed to this rate
  72.  -l, --list-only     List only mode (F/POP3)
  73.      --local-port RANGE  Force use of these local port numbers
  74.  -L, --location      Follow redirects (H)
  75.      --location-trusted like --location and send auth to other hosts (H)
  76.  -M, --manual        Display the full manual
  77.      --mail-from FROM  Mail from this address (SMTP)
  78.      --mail-rcpt TO  Mail to this/these addresses (SMTP)
  79.      --mail-auth AUTH  Originator address of the original email (SMTP)
  80.      --max-filesize BYTES  Maximum file size to download (H/F)
  81.      --max-redirs NUM  Maximum number of redirects allowed (H)
  82.  -m, --max-time SECONDS  Maximum time allowed for the transfer
  83.      --metalink      Process given URLs as metalink XML file
  84.      --negotiate     Use HTTP Negotiate Authentication (H)
  85.  -n, --netrc         Must read .netrc for user name and password
  86.      --netrc-optional Use either .netrc or URL; overrides -n
  87.      --netrc-file FILE  Set up the netrc filename to use
  88.  -N, --no-buffer     Disable buffering of the output stream
  89.      --no-keepalive  Disable keepalive use on the connection
  90.      --no-sessionid  Disable SSL session-ID reusing (SSL)
  91.      --noproxy       List of hosts which do not use proxy
  92.      --ntlm          Use HTTP NTLM authentication (H)
  93.      --oauth2-bearer TOKEN  OAuth 2 Bearer Token (IMAP, POP3, SMTP)
  94.  -o, --output FILE   Write output to <file> instead of stdout
  95.      --pass PASS     Pass phrase for the private key (SSL/SSH)
  96.      --post301       Do not switch to GET after following a 301 redirect (H)
  97.      --post302       Do not switch to GET after following a 302 redirect (H)
  98.      --post303       Do not switch to GET after following a 303 redirect (H)
  99.  -#, --progress-bar  Display transfer progress as a progress bar
  100.      --proto PROTOCOLS  Enable/disable specified protocols
  101.      --proto-redir PROTOCOLS  Enable/disable specified protocols on redirect
  102.  -x, --proxy [PROTOCOL://]HOST[:PORT] Use proxy on given port
  103.      --proxy-anyauth Pick "any" proxy authentication method (H)
  104.      --proxy-basic   Use Basic authentication on the proxy (H)
  105.      --proxy-digest  Use Digest authentication on the proxy (H)
  106.      --proxy-negotiate Use Negotiate authentication on the proxy (H)
  107.      --proxy-ntlm    Use NTLM authentication on the proxy (H)
  108.  -U, --proxy-user USER[:PASSWORD]  Proxy user and password
  109.      --proxy1.0 HOST[:PORT]  Use HTTP/1.0 proxy on given port
  110.  -p, --proxytunnel   Operate through a HTTP proxy tunnel (using CONNECT)
  111.      --pubkey KEY    Public key file name (SSH)
  112.  -Q, --quote CMD     Send command(s) to server before transfer (F/SFTP)
  113.      --random-file FILE  File for reading random data from (SSL)
  114.  -r, --range RANGE   Retrieve only the bytes within a range
  115.      --raw           Do HTTP "raw", without any transfer decoding (H)
  116.  -e, --referer       Referer URL (H)
  117.  -J, --remote-header-name Use the header-provided filename (H)
  118.  -O, --remote-name   Write output to a file named as the remote file
  119.      --remote-name-all Use the remote file name for all URLs
  120.  -R, --remote-time   Set the remote file's time on the local output
  121.  -X, --request COMMAND  Specify request command to use
  122.      --resolve HOST:PORT:ADDRESS  Force resolve of HOST:PORT to ADDRESS
  123.      --retry NUM   Retry request NUM times if transient problems occur
  124.      --retry-delay SECONDS When retrying, wait this many seconds between each
  125.      --retry-max-time SECONDS  Retry only within this period
  126.      --sasl-ir       Enable initial response in SASL authentication
  127.  -S, --show-error    Show error. With -s, make curl show errors when they occur
  128.  -s, --silent        Silent mode. Don't output anything
  129.      --socks4 HOST[:PORT]  SOCKS4 proxy on given host + port
  130.      --socks4a HOST[:PORT]  SOCKS4a proxy on given host + port
  131.      --socks5 HOST[:PORT]  SOCKS5 proxy on given host + port
  132.      --socks5-hostname HOST[:PORT] SOCKS5 proxy, pass host name to proxy
  133.      --socks5-gssapi-service NAME  SOCKS5 proxy service name for gssapi
  134.      --socks5-gssapi-nec  Compatibility with NEC SOCKS5 server
  135.  -Y, --speed-limit RATE  Stop transfers below speed-limit for 'speed-time' secs
  136.  -y, --speed-time SECONDS  Time for trig speed-limit abort. Defaults to 30
  137.      --ssl           Try SSL/TLS (FTP, IMAP, POP3, SMTP)
  138.      --ssl-reqd      Require SSL/TLS (FTP, IMAP, POP3, SMTP)
  139.  -2, --sslv2         Use SSLv2 (SSL)
  140.  -3, --sslv3         Use SSLv3 (SSL)
  141.      --ssl-allow-beast Allow security flaw to improve interop (SSL)
  142.      --stderr FILE   Where to redirect stderr. - means stdout
  143.      --tcp-nodelay   Use the TCP_NODELAY option
  144.  -t, --telnet-option OPT=VAL  Set telnet option
  145.      --tftp-blksize VALUE  Set TFTP BLKSIZE option (must be >512)
  146.  -z, --time-cond TIME  Transfer based on a time condition
  147.  -1, --tlsv1         Use TLSv1 (SSL)
  148.      --trace FILE    Write a debug trace to the given file
  149.      --trace-ascii FILE  Like --trace but without the hex output
  150.      --trace-time    Add time stamps to trace/verbose output
  151.      --tr-encoding   Request compressed transfer encoding (H)
  152.  -T, --upload-file FILE  Transfer FILE to destination
  153.      --url URL       URL to work with
  154.  -B, --use-ascii     Use ASCII/text transfer
  155.  -u, --user USER[:PASSWORD][;OPTIONS]  Server user, password and login options
  156.      --tlsuser USER  TLS username
  157.      --tlspassword STRING TLS password
  158.      --tlsauthtype STRING  TLS authentication type (default SRP)
  159.  -A, --user-agent STRING  User-Agent to send to server (H)
  160.  -v, --verbose       Make the operation more talkative
  161.  -V, --version       Show version number and quit
  162.  -w, --write-out FORMAT  What to output after completion
  163.      --xattr        Store metadata in extended file attributes
  164. -q                 If used as the first parameter disables .curlrc


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