命令:curl

目录

  • 命令:curl
  • 一、简介
  • 二、使用案例
  • 1、基本用法
  • 2、保存访问的网页
  • 2.1、使用linux的重定向功能保存
  • 2.2、可以使用curl的内置option:-o(小写)保存网页
  • 2.3、可以使用curl的内置option:-O(大写)保存网页中的文件
  • 3、测试网页返回值
  • 4、指定proxy服务器以及其端口
  • 5、cookie
  • 5.1、保存http的response里面的cookie信息。内置option:-c(小写)
  • 5.2、保存http的response里面的header信息。内置option: -D
  • 5.3、使用cookie
  • 6、模仿浏览器
  • 7、伪造referer(盗链)
  • 8、下载文件
  • 8.1、利用curl下载文件。
  • 8.2、循环下载
  • 8.3、下载重命名
  • 8.4、分块下载
  • 8.5、通过ftp下载文件
  • 8.6、显示下载进度条
  • 8.7、不会显示下载进度信息
  • 9、断点续传
  • 10、上传文件
  • 11、显示抓取错误
  • 三、man手册详情

一、简介

在Linux中curl是一个利用URL规则在命令行下工作的文件传输工具,可以说是一款很强大的http命令行工具。它支持文件的上传和下载,是综合传输工具,但按传统,习惯称url为下载工具。

语法:# curl [option] [url]

常见参数:

-A/--user-agent <string>              设置用户代理发送给服务器
-b/--cookie <name=string/file>    cookie字符串或文件读取位置
-c/--cookie-jar <file>                    操作结束后把cookie写入到这个文件中
-C/--continue-at <offset>            断点续转
-D/--dump-header <file>              把header信息写入到该文件中
-e/--referer                                  来源网址
-f/--fail                                          连接失败时不显示http错误
-o/--output                                  把输出写到该文件中
-O/--remote-name                      把输出写到该文件中,保留远程文件的文件名
-r/--range <range>                      检索来自HTTP/1.1或FTP服务器字节范围
-s/--silent                                    静音模式。不输出任何东西
-T/--upload-file <file>                  上传文件
-u/--user <user[:password]>      设置服务器的用户和密码
-w/--write-out [format]                什么输出完成后
-x/--proxy <host[:port]>              在给定的端口上使用HTTP代理
-#/--progress-bar                        进度条显示当前的传送状态

二、使用案例

1、基本用法

# curl http://www.linux.com

执行后,www.linux.com 的html就会显示在屏幕上了
Ps:由于安装linux的时候很多时候是没有安装桌面的,也意味着没有浏览器,因此这个方法也经常用于测试一台服务器是否可以到达一个网站

2、保存访问的网页

2.1、使用linux的重定向功能保存

# curl http://www.linux.com >> linux.html

2.2、可以使用curl的内置option:-o(小写)保存网页

$ curl -o linux.html http://www.linux.com

执行完成后会显示如下界面,显示100%则表示保存成功

% Total    % Received % Xferd  Average Speed  Time    Time    Time  Current
                                Dload  Upload  Total  Spent    Left  Speed
100 79684    0 79684    0    0  3437k      0 --:--:-- --:--:-- --:--:-- 7781k

2.3、可以使用curl的内置option:-O(大写)保存网页中的文件

要注意这里后面的url要具体到某个文件,不然抓不下来

# curl -O http://www.linux.com/hello.sh

3、测试网页返回值

# curl -o /dev/null -s -w %{http_code} www.linux.com

Ps:在脚本中,这是很常见的测试网站是否正常的用法

4、指定proxy服务器以及其端口

很多时候上网需要用到代理服务器(比如是使用代理服务器上网或者因为使用curl别人网站而被别人屏蔽IP地址的时候),幸运的是curl通过使用内置option:-x来支持设置代理

# curl -x 192.168.100.100:1080 http://www.linux.com

5、cookie

有些网站是使用cookie来记录session信息。对于chrome这样的浏览器,可以轻易处理cookie信息,但在curl中只要增加相关参数也是可以很容易的处理cookie

5.1、保存http的response里面的cookie信息。内置option:-c(小写)

# curl -c cookiec.txt  http://www.linux.com

执行后cookie信息就被存到了cookiec.txt里面了

5.2、保存http的response里面的header信息。内置option: -D

# curl -D cookied.txt http://www.linux.com

执行后cookie信息就被存到了cookied.txt里面了

注意:-c(小写)产生的cookie和-D里面的cookie是不一样的。

5.3、使用cookie

很多网站都是通过监视你的cookie信息来判断你是否按规矩访问他们的网站的,因此我们需要使用保存的cookie信息。内置option: -b

# curl -b cookiec.txt http://www.linux.com

6、模仿浏览器

有些网站需要使用特定的浏览器去访问他们,有些还需要使用某些特定的版本。curl内置option:-A可以让我们指定浏览器去访问网站

# curl -A "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.0)" http://www.linux.com

这样服务器端就会认为是使用IE8.0去访问的

7、伪造referer(盗链)

很多服务器会检查http访问的referer从而来控制访问。比如:你是先访问首页,然后再访问首页中的邮箱页面,这里访问邮箱的referer地址就是访问首页成功后的页面地址,如果服务器发现对邮箱页面访问的referer地址不是首页的地址,就断定那是个盗连了
curl中内置option:-e可以让我们设定referer

# curl -e "www.linux.com" http://mail.linux.com

这样就会让服务器其以为你是从www.linux.com点击某个链接过来的

8、下载文件

8.1、利用curl下载文件。

#使用内置option:-o(小写)

# curl -o dodo1.jpg http:www.linux.com/dodo1.JPG

#使用内置option:-O(大写)

# curl -O http://www.linux.com/dodo1.JPG

这样就会以服务器上的名称保存文件到本地

8.2、循环下载

有时候下载图片可以能是前面的部分名称是一样的,就最后的尾椎名不一样

# curl -O http://www.linux.com/dodo[1-5].JPG

这样就会把dodo1,dodo2,dodo3,dodo4,dodo5全部保存下来

8.3、下载重命名

# curl -O http://www.linux.com/{hello,bb}/dodo[1-5].JPG

由于下载的hello与bb中的文件名都是dodo1,dodo2,dodo3,dodo4,dodo5。因此第二次下载的会把第一次下载的覆盖,这样就需要对文件进行重命名。

# curl -o #1_#2.JPG http://www.linux.com/{hello,bb}/dodo[1-5].JPG

这样在hello/dodo1.JPG的文件下载下来就会变成hello_dodo1.JPG,其他文件依此类推,从而有效的避免了文件被覆盖

8.4、分块下载

有时候下载的东西会比较大,这个时候我们可以分段下载。使用内置option:-r

# curl -r 0-100 -o dodo1_part1.JPG http://www.linux.com/dodo1.JPG
# curl -r 100-200 -o dodo1_part2.JPG http://www.linux.com/dodo1.JPG
# curl -r 200- -o dodo1_part3.JPG http://www.linux.com/dodo1.JPG
# cat dodo1_part* > dodo1.JPG

这样就可以查看dodo1.JPG的内容了

8.5、通过ftp下载文件

curl可以通过ftp下载文件,curl提供两种从ftp中下载的语法

# curl -O -u 用户名:密码 ftp://www.linux.com/dodo1.JPG
# curl -O ftp://用户名:密码@www.linux.com/dodo1.JPG

8.6、显示下载进度条

# curl -# -O http://www.linux.com/dodo1.JPG

8.7、不会显示下载进度信息

# curl -s -O http://www.linux.com/dodo1.JPG

9、断点续传

在windows中,我们可以使用迅雷这样的软件进行断点续传。curl可以通过内置option:-C同样可以达到相同的效果
如果在下载dodo1.JPG的过程中突然掉线了,可以使用以下的方式续传

# curl -C -O http://www.linux.com/dodo1.JPG

10、上传文件

curl不仅仅可以下载文件,还可以上传文件。通过内置option:-T来实现

# curl -T dodo1.JPG -u 用户名:密码 ftp://www.linux.com/img/

这样就向ftp服务器上传了文件dodo1.JPG

11、显示抓取错误

# curl -f http://www.linux.com/error

其他参数(此处翻译为转载)

-a/--append                        上传文件时,附加到目标文件
--anyauth                            可以使用“任何”身份验证方法
--basic                                使用HTTP基本验证
-B/--use-ascii                      使用ASCII文本传输
-d/--data <data>                  HTTP POST方式传送数据
--data-ascii <data>            以ascii的方式post数据
--data-binary <data>          以二进制的方式post数据
--negotiate                          使用HTTP身份验证
--digest                        使用数字身份验证
--disable-eprt                  禁止使用EPRT或LPRT
--disable-epsv                  禁止使用EPSV
--egd-file <file>              为随机数据(SSL)设置EGD socket路径
--tcp-nodelay                  使用TCP_NODELAY选项
-E/--cert <cert[:passwd]>      客户端证书文件和密码 (SSL)
--cert-type <type>              证书文件类型 (DER/PEM/ENG) (SSL)
--key <key>                    私钥文件名 (SSL)
--key-type <type>              私钥文件类型 (DER/PEM/ENG) (SSL)
--pass  <pass>                  私钥密码 (SSL)
--engine <eng>                  加密引擎使用 (SSL). "--engine list" for list
--cacert <file>                CA证书 (SSL)
--capath <directory>            CA目   (made using c_rehash) to verify peer against (SSL)
--ciphers <list>                SSL密码
--compressed                    要求返回是压缩的形势 (using deflate or gzip)
--connect-timeout <seconds>    设置最大请求时间
--create-dirs                  建立本地目录的目录层次结构
--crlf                          上传是把LF转变成CRLF
--ftp-create-dirs              如果远程目录不存在,创建远程目录
--ftp-method [multicwd/nocwd/singlecwd]    控制CWD的使用
--ftp-pasv                      使用 PASV/EPSV 代替端口
--ftp-skip-pasv-ip              使用PASV的时候,忽略该IP地址
--ftp-ssl                      尝试用 SSL/TLS 来进行ftp数据传输
--ftp-ssl-reqd                  要求用 SSL/TLS 来进行ftp数据传输
-F/--form <name=content>        模拟http表单提交数据
-form-string <name=string>      模拟http表单提交数据
-g/--globoff                    禁用网址序列和范围使用{}和[]
-G/--get                        以get的方式来发送数据
-h/--help                      帮助
-H/--header <line>              自定义头信息传递给服务器
--ignore-content-length        忽略的HTTP头信息的长度
-i/--include                    输出时包括protocol头信息
-I/--head                      只显示文档信息
-j/--junk-session-cookies      读取文件时忽略session cookie
--interface <interface>        使用指定网络接口/地址
--krb4 <level>                  使用指定安全级别的krb4
-k/--insecure                  允许不使用证书到SSL站点
-K/--config                    指定的配置文件读取
-l/--list-only                  列出ftp目录下的文件名称
--limit-rate <rate>            设置传输速度
--local-port<NUM>              强制使用本地端口号
-m/--max-time <seconds>        设置最大传输时间
--max-redirs <num>              设置最大读取的目录数
--max-filesize <bytes>          设置最大下载的文件总量
-M/--manual                    显示全手动
-n/--netrc                      从netrc文件中读取用户名和密码
--netrc-optional                使用 .netrc 或者 URL来覆盖-n
--ntlm                          使用 HTTP NTLM 身份验证
-N/--no-buffer                  禁用缓冲输出
-p/--proxytunnel                使用HTTP代理
--proxy-anyauth                选择任一代理身份验证方法
--proxy-basic                  在代理上使用基本身份验证
--proxy-digest                  在代理上使用数字身份验证
--proxy-ntlm                    在代理上使用ntlm身份验证
-P/--ftp-port <address>        使用端口地址,而不是使用PASV
-Q/--quote <cmd>                文件传输前,发送命令到服务器
--range-file                    读取(SSL)的随机文件
-R/--remote-time                在本地生成文件时,保留远程文件时间
--retry <num>                  传输出现问题时,重试的次数
--retry-delay <seconds>        传输出现问题时,设置重试间隔时间
--retry-max-time <seconds>      传输出现问题时,设置最大重试时间
-S/--show-error                显示错误
--socks4 <host[:port]>          用socks4代理给定主机和端口
--socks5 <host[:port]>          用socks5代理给定主机和端口
-t/--telnet-option <OPT=val>    Telnet选项设置
--trace <file>                  对指定文件进行debug
--trace-ascii <file>            Like --跟踪但没有hex输出
--trace-time                    跟踪/详细输出时,添加时间戳
--url <URL>                    Spet URL to work with
-U/--proxy-user <user[:password]>  设置代理用户名和密码
-V/--version                    显示版本信息
-X/--request <command>          指定什么命令
-y/--speed-time                放弃限速所要的时间。默认为30
-Y/--speed-limit                停止传输速度的限制,速度时间'秒
-z/--time-cond                  传送时间设置
-0/--http1.0                    使用HTTP 1.0
-1/--tlsv1                      使用TLSv1(SSL)
-2/--sslv2                      使用SSLv2的(SSL)
-3/--sslv3                      使用的SSLv3(SSL)
--3p-quote                      like -Q for the source URL for 3rd party transfer
--3p-url                        使用url,进行第三方传送
--3p-user                      使用用户名和密码,进行第三方传送
-4/--ipv4                      使用IP4
-6/--ipv6                      使用IP6

三、man手册详情

curl(1)                                                                                 Curl Manual                                                                                curl(1)

NAME
       curl - transfer a URL

SYNOPSIS
       curl [options] [URL...]

DESCRIPTION
       curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP,
       RTSP, SCP, SFTP, SMTP, SMTPS, TELNET and TFTP).  The command is designed to work without user interaction.

       curl offers a busload of useful tricks like proxy support, user authentication, FTP upload, HTTP post, SSL connections, cookies, file transfer resume, Metalink, and more.  As  you
       will see below, the number of features will make your head spin!

       curl is powered by libcurl for all transfer-related features. See libcurl(3) for details.

URL
       The URL syntax is protocol-dependent. You'll find a detailed description in RFC 3986.

       You can specify multiple URLs or parts of URLs by writing part sets within braces as in:

        http://site.{one,two,three}.com

       or you can get sequences of alphanumeric series by using [] as in:

        ftp://ftp.numericals.com/file[1-100].txt
        ftp://ftp.numericals.com/file[001-100].txt    (with leading zeros)
        ftp://ftp.letters.com/file[a-z].txt

       Nested sequences are not supported, but you can use several ones next to each other:

        http://any.org/archive[1996-1999]/vol[1-4]/part{a,b,c}.html

       You can specify any amount of URLs on the command line. They will be fetched in a sequential manner in the specified order.

       You can specify a step counter for the ranges to get every Nth number or letter:

        http://www.numericals.com/file[1-100:10].txt
        http://www.letters.com/file[a-z:2].txt

       If  you  specify  URL without protocol:// prefix, curl will attempt to guess what protocol you might want. It will then default to HTTP but try other protocols based on often-used
       host name prefixes. For example, for host names starting with "ftp." curl will assume you want to speak FTP.

       curl will do its best to use what you pass to it as a URL. It is not trying to validate it as a syntactically correct URL by any means but is instead very  liberal  with  what  it
       accepts.
curl  will  attempt  to  re-use  connections for multiple file transfers, so that getting many files from the same server will not do multiple connects / handshakes. This improves
       speed. Of course this is only done on files specified on a single command line and cannot be used between separate curl invokes.

PROGRESS METER
       curl normally displays a progress meter during operations, indicating the amount of transferred data, transfer speeds and estimated time left, etc.

       curl displays this data to the terminal by default, so if you invoke curl to do an operation and it is about to write data to the terminal, it disables the progress meter as  oth‐
       erwise it would mess up the output mixing progress meter and response data.

       If you want a progress meter for HTTP POST or PUT requests, you need to redirect the response output to a file, using shell redirect (>), -o [file] or similar.

       It is not the same case for FTP upload as that operation does not spit out any response data to the terminal.

       If you prefer a progress "bar" instead of the regular meter, -# is your friend.

OPTIONS
       In  general,  all boolean options are enabled with --option and yet again disabled with --no-option. That is, you use the exact same option name but prefix it with "no-". However,
       in this list we mostly only list and show the --option version of them. (This concept with --no options was added in  7.19.0.  Previously  most  options  were  toggled  on/off  on
       repeated use of the same command line option.)

       -#, --progress-bar
              Make curl display progress as a simple progress bar instead of the standard, more informational, meter.

       -0, --http1.0
              (HTTP) Forces curl to issue its requests using HTTP 1.0 instead of using its internally preferred: HTTP 1.1.

       -1, --tlsv1
              (SSL) Forces curl to use TLS version 1.x when negotiating with a remote TLS server.  You can use options --tlsv1.0, --tlsv1.1, and --tlsv1.2 to control the TLS version more
              precisely (if the SSL backend in use supports such a level of control).

       -2, --sslv2
              (SSL) Forces curl to use SSL version 2 when negotiating with a remote SSL server.
 -3, --sslv3
              (SSL) Forces curl to use SSL version 3 when negotiating with a remote SSL server.

       -4, --ipv4
              If curl is capable of resolving an address to multiple IP versions (which it is if it is IPv6-capable), this option tells curl to resolve names to IPv4 addresses only.

       -6, --ipv6
              If curl is capable of resolving an address to multiple IP versions (which it is if it is IPv6-capable), this option tells curl to resolve names to IPv6 addresses only.

       -a, --append
              (FTP/SFTP) When used in an upload, this will tell curl to append to the target file instead of overwriting it. If the file doesn't exist, it will  be  created.   Note  that
              this flag is ignored by some SSH servers (including OpenSSH).

       -A, --user-agent <agent string>
              (HTTP)  Specify  the  User-Agent string to send to the HTTP server. Some badly done CGIs fail if this field isn't set to "Mozilla/4.0". To encode blanks in the string, sur‐
              round the string with single quote marks. This can also be set with the -H, --header option of course.

              If this option is used several times, the last one will be used.

       --anyauth
              (HTTP) Tells curl to figure out authentication method by itself, and use the most secure one the remote site claims to support. This is done by first doing  a  request  and
              checking  the  response-headers, thus possibly inducing an extra network round-trip. This is used instead of setting a specific authentication method, which you can do with
              --basic, --digest, --ntlm, and --negotiate.

              Note that using --anyauth is not recommended if you do uploads from stdin, since it may require data to be sent twice and then the client must be able  to  rewind.  If  the
              need should arise when uploading from stdin, the upload operation will fail.

       -b, --cookie <name=data>
              (HTTP)  Pass the data to the HTTP server as a cookie. It is supposedly the data previously received from the server in a "Set-Cookie:" line.  The data should be in the for‐
              mat "NAME1=VALUE1; NAME2=VALUE2".

              If no '=' symbol is used in the line, it is treated as a filename to use to read previously stored cookie lines from, which should be used in this session  if  they  match.
              Using  this  method also activates the "cookie parser" which will make curl record incoming cookies too, which may be handy if you're using this in combination with the -L,
              --location option. The file format of the file to read cookies from should be plain HTTP headers or the Netscape/Mozilla cookie file format.

              NOTE that the file specified with -b, --cookie is only used as input. No cookies will be stored in the file. To store cookies, use the -c, --cookie-jar option or you  could
              even save the HTTP headers to a file using -D, --dump-header!

              If this option is used several times, the last one will be used.

       -B, --use-ascii
              (FTP/LDAP) Enable ASCII transfer. For FTP, this can also be enforced by using an URL that ends with ";type=A". This option causes data sent to stdout to be in text mode for
              win32 systems.
       --basic
              (HTTP) Tells curl to use HTTP Basic authentication. This is the default and this option is usually pointless, unless you use it to override a  previously  set  option  that
              sets a different authentication method (such as --ntlm, --digest, or --negotiate).

       -c, --cookie-jar <file name>
              (HTTP)  Specify  to  which file you want curl to write all cookies after a completed operation. Curl writes all cookies previously read from a specified file as well as all
              cookies received from remote server(s). If no cookies are known, no file will be written. The file will be written using the Netscape cookie file format.  If  you  set  the
              file name to a single dash, "-", the cookies will be written to stdout.

              This command line option will activate the cookie engine that makes curl record and use cookies. Another way to activate it is to use the -b, --cookie option.

              If  the  cookie  jar can't be created or written to, the whole curl operation won't fail or even report an error clearly. Using -v will get a warning displayed, but that is
              the only visible feedback you get about this possibly lethal situation.

              If this option is used several times, the last specified file name will be used.

       -C, --continue-at <offset>
              Continue/Resume a previous file transfer at the given offset. The given offset is the exact number of bytes that will be skipped, counting from the beginning of the  source
              file before it is transferred to the destination.  If used with uploads, the FTP server command SIZE will not be used by curl.

              Use "-C -" to tell curl to automatically find out where/how to resume the transfer. It then uses the given output/input files to figure that out.

              If this option is used several times, the last one will be used.

       --ciphers <list of ciphers>
              (SSL)  Specifies  which  ciphers  to  use  in  the  connection.  The  list  of  ciphers  must  specify  valid  ciphers.  Read  up  on  SSL  cipher list details on this URL:
              http://www.openssl.org/docs/apps/ciphers.html

              NSS  ciphers  are  done  differently  than  OpenSSL  and  GnuTLS.  The  full  list  of  NSS  ciphers  is  in  the  NSSCipherSuite  entry  at  this  URL:  http://git.fedora‐
              hosted.org/cgit/mod_nss.git/plain/docs/mod_nss.html#Directives

              If this option is used several times, the last one will be used.

       --compressed
              (HTTP)  Request  a compressed response using one of the algorithms curl supports, and save the uncompressed document.  If this option is used and the server sends an unsup‐
              ported encoding, curl will report an error.

       --connect-timeout <seconds>
              Maximum time in seconds that you allow the connection to the server to take.  This only limits the connection phase, once curl has connected this option is of no more  use.
              See also the -m, --max-time option.

              If this option is used several times, the last one will be used.

       --create-dirs
              When  used in conjunction with the -o option, curl will create the necessary local directory hierarchy as needed. This option creates the dirs mentioned with the -o option,
              nothing else. If the -o file name uses no dir or if the dirs it mentions already exist, no dir will be created.
              To create remote directories when using FTP or SFTP, try --ftp-create-dirs.

       --crlf (FTP) Convert LF to CRLF in upload. Useful for MVS (OS/390).

       --crlfile <file>
              (HTTPS/FTPS) Provide a file using PEM format with a Certificate Revocation List that may specify peer certificates that are to be considered revoked.

              If this option is used several times, the last one will be used.

              (Added in 7.19.7)

       -d, --data <data>
              (HTTP) Sends the specified data in a POST request to the HTTP server, in the same way that a browser does when a user has filled in an HTML form and presses the submit but‐
              ton. This will cause curl to pass the data to the server using the content-type application/x-www-form-urlencoded.  Compare to -F, --form.

              -d,  --data  is  the  same as --data-ascii. To post data purely binary, you should instead use the --data-binary option. To URL-encode the value of a form field you may use
              --data-urlencode.

              If any of these options is used more than once on the same command line, the data pieces specified will be merged together with  a  separating  &-symbol.  Thus,  using  '-d
              name=daniel -d skill=lousy' would generate a post chunk that looks like 'name=daniel&skill=lousy'.

              If  you start the data with the letter @, the rest should be a file name to read the data from, or - if you want curl to read the data from stdin.  The contents of the file
              must already be URL-encoded. Multiple files can also be specified. Posting data from a file named 'foobar' would thus be done with --data @foobar.

       -D, --dump-header <file>
              Write the protocol headers to the specified file.

              This option is handy to use when you want to store the headers that an HTTP site sends to you. Cookies from the headers could then be read in a second  curl  invocation  by
              using the -b, --cookie option! The -c, --cookie-jar option is however a better way to store cookies.

              When used in FTP, the FTP server response lines are considered being "headers" and thus are saved there.

              If this option is used several times, the last one will be used.

       --data-ascii <data>
              See -d, --data.

       --data-binary <data>
              (HTTP) This posts data exactly as specified with no extra processing whatsoever.

              If  you  start  the  data with the letter @, the rest should be a filename.  Data is posted in a similar manner as --data-ascii does, except that newlines are preserved and
              conversions are never done.

              If this option is used several times, the ones following the first will append data as described in -d, --data.

       --data-urlencode <data>
              (HTTP) This posts data, similar to the other --data options with the exception that this performs URL-encoding. (Added in 7.18.0)
              To be CGI-compliant, the <data> part should begin with a name followed by a separator and a content specification. The <data> part can be passed to curl using  one  of  the
              following syntaxes:

              content
                     This  will make curl URL-encode the content and pass that on. Just be careful so that the content doesn't contain any = or @ symbols, as that will then make the syn‐
                     tax match one of the other cases below!

              =content
                     This will make curl URL-encode the content and pass that on. The preceding = symbol is not included in the data.

              name=content
                     This will make curl URL-encode the content part and pass that on. Note that the name part is expected to be URL-encoded already.

              @filename
                     This will make curl load data from the given file (including any newlines), URL-encode that data and pass it on in the POST.

              name@filename
                     This will make curl load data from the given file (including any newlines), URL-encode that data and pass it on in the  POST.  The  name  part  gets  an  equal  sign
                     appended, resulting in name=urlencoded-file-content. Note that the name is expected to be URL-encoded already.

       --delegation LEVEL
              Set LEVEL to tell the server what it is allowed to delegate when it comes to user credentials. Used with GSS/kerberos.

              none   Don't allow any delegation.

              policy Delegates if and only if the OK-AS-DELEGATE flag is set in the Kerberos service ticket, which is a matter of realm policy.

              always Unconditionally allow the server to delegate.

       --digest
              (HTTP)  Enables HTTP Digest authentication. This is an authentication scheme that prevents the password from being sent over the wire in clear text. Use this in combination
              with the normal -u, --user option to set user name and password. See also --ntlm, --negotiate and --anyauth for related options.

              If this option is used several times, only the first one is used.

       --disable-eprt
              (FTP) Tell curl to disable the use of the EPRT and LPRT commands when doing active FTP transfers. Curl will normally always first attempt to  use  EPRT,  then  LPRT  before
              using  PORT,  but with this option, it will use PORT right away. EPRT and LPRT are extensions to the original FTP protocol, and may not work on all servers, but they enable
              more functionality in a better way than the traditional PORT command.

              --eprt can be used to explicitly enable EPRT again and --no-eprt is an alias for --disable-eprt.

              If the server is an IPv6 host, this option will have no effect as EPRT is necessary then.
              Disabling EPRT only changes the active behavior. If you want to switch to passive mode you need to not use -P, --ftp-port or force it with --ftp-pasv.

       --disable-epsv
              (FTP) Tell curl to disable the use of the EPSV command when doing passive FTP transfers. Curl will normally always first attempt to use EPSV  before  PASV,  but  with  this
              option, it will not try using EPSV.

              --epsv can be used to explicitly enable EPSV again and --no-epsv is an alias for --disable-epsv.

              If the server is an IPv6 host, this option will have no effect as EPSV is necessary then.

              Disabling EPSV only changes the passive behavior. If you want to switch to active mode you need to use -P, --ftp-port.

       -e, --referer <URL>
              (HTTP)  Sends  the  "Referer  Page" information to the HTTP server. This can also be set with the -H, --header flag of course.  When used with -L, --location you can append
              ";auto" to the --referer URL to make curl automatically set the previous URL when it follows a Location: header. The ";auto" string can be used alone, even if you don't set
              an initial --referer.

              If this option is used several times, the last one will be used.

       -E, --cert <certificate[:password]>
              (SSL) Tells curl to use the specified client certificate file when getting a file with HTTPS, FTPS or another SSL-based protocol. The certificate must be in PEM format.  If
              the optional password isn't specified, it will be queried for on the terminal. Note that this option assumes a "certificate" file that is the private key  and  the  private
              certificate concatenated! See --cert and --key to specify them independently.

              If  curl is built against the NSS SSL library then this option can tell curl the nickname of the certificate to use within the NSS database defined by the environment vari‐
              able SSL_DIR (or by default /etc/pki/nssdb). If the NSS PEM PKCS#11 module (libnsspem.so) is available then PEM files may be loaded. If you want to use a file from the cur‐
              rent directory, please precede it with "./" prefix, in order to avoid confusion with a nickname.  If the nickname contains ":", it needs to be preceded by "\" so that it is
              not recognized as password delimiter.  If the nickname contains "\", it needs to be escaped as "\\" so that it is not recognized as an escape character.

              If this option is used several times, the last one will be used.

       --engine <name>
              Select the OpenSSL crypto engine to use for cipher operations. Use --engine list to print a list of build-time supported engines. Note that not all (or none) of the engines
              may be available at run-time.

       --environment
              (RISC OS ONLY) Sets a range of environment variables, using the names the -w option supports, to allow easier extraction of useful information after having run curl.

       --egd-file <file>
              (SSL) Specify the path name to the Entropy Gathering Daemon socket. The socket is used to seed the random engine for SSL connections. See also the --random-file option.

       --cert-type <type>
              (SSL) Tells curl what certificate type the provided certificate is in. PEM, DER and ENG are recognized types.  If not specified, PEM is assumed.

              If this option is used several times, the last one will be used.

       --cacert <CA certificate>
              (SSL) Tells curl to use the specified certificate file to verify the peer. The file may contain multiple CA certificates. The certificate(s) must be in PEM format. Normally
              curl is built to use a default file for this, so this option is typically used to alter that default file.

              curl recognizes the environment variable named 'CURL_CA_BUNDLE' if it is set, and uses the given path as a path to a CA cert bundle. This option overrides that variable.

              The windows version of curl will automatically look for a CA certs file named ´curl-ca-bundle.crt´, either in the same directory as curl.exe,  or  in  the  Current  Working
              Directory, or in any folder along your PATH.

              If curl is built against the NSS SSL library, the NSS PEM PKCS#11 module (libnsspem.so) needs to be available for this option to work properly.

              If this option is used several times, the last one will be used.

       --capath <CA certificate directory>
              (SSL)  Tells curl to use the specified certificate directory to verify the peer. Multiple paths can be provided by separating them with ":" (e.g.  "path1:path2:path3"). The
              certificates must be in PEM format, and if curl is built against OpenSSL, the directory must have been processed using the c_rehash utility  supplied  with  OpenSSL.  Using
              --capath can allow OpenSSL-powered curl to make SSL-connections much more efficiently than using --cacert if the --cacert file contains many CA certificates.

              If this option is set, the default capath value will be ignored, and if it is used several times, the last one will be used.

       -f, --fail
              (HTTP) Fail silently (no output at all) on server errors. This is mostly done to better enable scripts etc to better deal with failed attempts. In normal cases when an HTTP
              server fails to deliver a document, it returns an HTML document stating so (which often also describes why and more). This flag will prevent curl from outputting  that  and
              return error 22.

              This  method  is not fail-safe and there are occasions where non-successful response codes will slip through, especially when authentication is involved (response codes 401
              and 407).

       -F, --form <name=content>
              (HTTP) This lets curl emulate a filled-in form in which a user has pressed the submit button. This causes curl to  POST  data  using  the  Content-Type  multipart/form-data
              according  to  RFC  2388. This enables uploading of binary files etc. To force the 'content' part to be a file, prefix the file name with an @ sign. To just get the content
              part from a file, prefix the file name with the symbol <. The difference between @ and < is then that @ makes a file get attached in the post as a file upload, while the  <
              makes a text field and just get the contents for that text field from a file.

              Example, to send your password file to the server, where 'password' is the name of the form-field to which /etc/passwd will be the input:

              curl -F password=@/etc/passwd www.mypasswords.com

              To read content from stdin instead of a file, use - as the filename. This goes for both @ and < constructs.

              You can also tell curl what Content-Type to use by using 'type=', in a manner similar to:
              curl -F "web=@index.html;type=text/html" url.com

              or

              curl -F "name=daniel;type=text/foo" url.com

              You can also explicitly change the name field of a file upload part by setting filename=, like this:

              curl -F "file=@localfile;filename=nameinpost" url.com

              If filename/path contains ',' or ';', it must be quoted by double-quotes like:

              curl -F "file=@\"localfile\";filename=\"nameinpost\"" url.com

              or

              curl -F 'file=@"localfile";filename="nameinpost"' url.com

              Note that if a filename/path is quoted by double-quotes, any double-quote or backslash within the filename must be escaped by backslash.

              See further examples and details in the MANUAL.

              This option can be used multiple times.

       --ftp-account [data]
              (FTP) When an FTP server asks for "account data" after user name and password has been provided, this data is sent off using the ACCT command. (Added in 7.13.0)

              If this option is used several times, the last one will be used.

       --ftp-alternative-to-user <command>
              (FTP) If authenticating with the USER and PASS commands fails, send this command.  When connecting to Tumbleweed's Secure Transport server over FTPS using a client certifi‐
              cate, using "SITE AUTH" will tell the server to retrieve the username from the certificate. (Added in 7.15.5)

       --ftp-create-dirs
              (FTP/SFTP) When an FTP or SFTP URL/operation uses a path that doesn't currently exist on the server, the standard behavior of curl is to fail. Using this option, curl  will
              instead attempt to create missing directories.

       --ftp-method [method]
              (FTP) Control what method curl should use to reach a file on an FTP(S) server. The method argument should be one of the following alternatives:
              multicwd
                     curl  does  a  single  CWD  operation for each path part in the given URL. For deep hierarchies this means very many commands. This is how RFC 1738 says it should be
                     done. This is the default but the slowest behavior.

              nocwd  curl does no CWD at all. curl will do SIZE, RETR, STOR etc and give a full path to the server for all these commands. This is the fastest behavior.

              singlecwd
                     curl does one CWD with the full target directory and then operates on the file "normally" (like in the multicwd case). This is somewhat more standards compliant than
                     'nocwd' but without the full penalty of 'multicwd'.
       (Added in 7.15.1)

       --ftp-pasv
              (FTP)  Use  passive  mode  for  the data connection. Passive is the internal default behavior, but using this option can be used to override a previous -P/-ftp-port option.
              (Added in 7.11.0)

              If this option is used several times, only the first one is used. Undoing an enforced passive really isn't doable but you must then instead enforce the correct  -P,  --ftp-
              port again.

              Passive mode means that curl will try the EPSV command first and then PASV, unless --disable-epsv is used.

       --ftp-skip-pasv-ip
              (FTP)  Tell  curl  to not use the IP address the server suggests in its response to curl's PASV command when curl connects the data connection. Instead curl will re-use the
              same IP address it already uses for the control connection. (Added in 7.14.2)

              This option has no effect if PORT, EPRT or EPSV is used instead of PASV.

       --ftp-pret
              (FTP) Tell curl to send a PRET command before PASV (and EPSV). Certain FTP servers, mainly drftpd, require this non-standard command for directory listings as  well  as  up
              and downloads in PASV mode.  (Added in 7.20.x)

       --ftp-ssl-ccc
              (FTP)  Use CCC (Clear Command Channel) Shuts down the SSL/TLS layer after authenticating. The rest of the control channel communication will be unencrypted. This allows NAT
              routers to follow the FTP transaction. The default mode is passive. See --ftp-ssl-ccc-mode for other modes.  (Added in 7.16.1)

       --ftp-ssl-ccc-mode [active/passive]
              (FTP) Use CCC (Clear Command Channel) Sets the CCC mode. The passive mode will not initiate the shutdown, but instead wait for the server to do it, and will  not  reply  to
              the shutdown from the server. The active mode initiates the shutdown and waits for a reply from the server.  (Added in 7.16.2)

       --ftp-ssl-control
              (FTP)  Require  SSL/TLS  for  the  FTP login, clear for transfer.  Allows secure authentication, but non-encrypted data transfers for efficiency.  Fails the transfer if the
              server doesn't support SSL/TLS.  (Added in 7.16.0) that can still be used but will be removed in a future version.

       --form-string <name=string>
              (HTTP) Similar to --form except that the value string for the named parameter is used literally. Leading '@' and '<' characters, and the ';type=' string in the  value  have
              no special meaning. Use this in preference to --form if there's any possibility that the string value may accidentally trigger the '@' or '<' features of --form.
       -g, --globoff
              This  option  switches  off the "URL globbing parser". When you set this option, you can specify URLs that contain the letters {}[] without having them being interpreted by
              curl itself. Note that these letters are not normal legal URL contents but they should be encoded according to the URI standard.

       -G, --get
              When used, this option will make all data specified with -d, --data or --data-binary to be used in an HTTP GET request instead of the POST request that otherwise  would  be
              used. The data will be appended to the URL with a '?' separator.

              If used in combination with -I, the POST data will instead be appended to the URL with a HEAD request.

              If  this  option  is  used  several times, only the first one is used. This is because undoing a GET doesn't make sense, but you should then instead enforce the alternative
              method you prefer.

       -H, --header <header>
              (HTTP) Extra header to use when getting a web page. You may specify any number of extra headers. Note that if you should add a custom header that has the same name  as  one
              of  the  internal ones curl would use, your externally set header will be used instead of the internal one. This allows you to make even trickier stuff than curl would nor‐
              mally do. You should not replace internally set headers without knowing perfectly well what you're doing. Remove an internal header by giving a replacement without  content
              on  the  right  side of the colon, as in: -H "Host:". If you send the custom header with no-value then its header must be terminated with a semicolon, such as -H "X-Custom-
              Header;" to send "X-Custom-Header:".

              curl will make sure that each header you add/replace is sent with the proper end-of-line marker, you should thus not add that as a part of the header content:  do  not  add
              newlines or carriage returns, they will only mess things up for you.

              See also the -A, --user-agent and -e, --referer options.

              This option can be used multiple times to add/replace/remove multiple headers.

       --hostpubmd5 <md5>
              (SCP/SFTP)  Pass  a  string containing 32 hexadecimal digits. The string should be the 128 bit MD5 checksum of the remote host's public key, curl will refuse the connection
              with the host unless the md5sums match. (Added in 7.17.1)

       --ignore-content-length
              (HTTP) Ignore the Content-Length header. This is particularly useful for servers running Apache 1.x, which will report incorrect Content-Length  for  files  larger  than  2
              gigabytes.

       -i, --include
              (HTTP) Include the HTTP-header in the output. The HTTP-header includes things like server-name, date of the document, HTTP-version and more...

       -I, --head
              (HTTP/FTP/FILE)  Fetch  the HTTP-header only! HTTP-servers feature the command HEAD which this uses to get nothing but the header of a document. When used on an FTP or FILE
              file, curl displays the file size and last modification time only.

       --interface <name>
              Perform an operation using a specified interface. You can enter interface name, IP address or host name. An example could look like:
               curl --interface eth0:1 http://www.netscape.com/

              If this option is used several times, the last one will be used.

       -j, --junk-session-cookies
              (HTTP) When curl is told to read cookies from a given file, this option will make it discard all "session cookies". This will basically have the same effect  as  if  a  new
              session is started. Typical browsers always discard session cookies when they're closed down.

       -J, --remote-header-name
              (HTTP) This option tells the -O, --remote-name option to use the server-specified Content-Disposition filename instead of extracting a filename from the URL.

       -k, --insecure
              (SSL)  This  option explicitly allows curl to perform "insecure" SSL connections and transfers. All SSL connections are attempted to be made secure by using the CA certifi‐
              cate bundle installed by default. This makes all connections considered "insecure" fail unless -k, --insecure is used.

              See this online resource for further details: http://curl.haxx.se/docs/sslcerts.html

       -K, --config <config file>
              Specify which config file to read curl arguments from. The config file is a text file in which command line arguments can be written which then will be used as if they were
              written on the actual command line. Options and their parameters must be specified on the same config file line, separated by whitespace, colon, the equals sign or any com‐
              bination thereof (however, the preferred separator is the equals sign). If the parameter is to contain whitespace, the parameter must be enclosed within quotes. Within dou‐
              ble quotes, the following escape sequences are available: \\, \", \t, \n, \r and \v. A backslash preceding any other letter is ignored. If the first column of a config line
              is a '#' character, the rest of the line will be treated as a comment. Only write one option per physical line in the config file.

              Specify the filename to -K, --config as '-' to make curl read the file from stdin.

              Note that to be able to specify a URL in the config file, you need to specify it using the --url option, and not by simply writing the URL on its own  line.  So,  it  could
              look similar to this:

              url = "http://curl.haxx.se/docs/"

              Long option names can optionally be given in the config file without the initial double dashes.

              When curl is invoked, it always (unless -q is used) checks for a default config file and uses it if found. The default config file is checked for in the following places in
              this order:

              1) curl tries to find the "home dir": It first checks for the CURL_HOME and then the HOME environment variables. Failing that,  it  uses  getpwuid()  on  UNIX-like  systems
              (which  returns the home dir given the current user in your system). On Windows, it then checks for the APPDATA variable, or as a last resort the '%USERPROFILE%\Application
              Data'.

              2) On windows, if there is no _curlrc file in the home dir, it checks for one in the same dir the curl executable is placed. On UNIX-like systems, it  will  simply  try  to
              load .curlrc from the determined home dir.
              # --- Example file ---
              # this is a comment
              url = "curl.haxx.se"
              output = "curlhere.html"
              user-agent = "superagent/1.0"

              # and fetch another URL too
              url = "curl.haxx.se/docs/manpage.html"
              -O
              referer = "http://nowhereatall.com/"
              # --- End of example file ---

              This option can be used multiple times to load multiple config files.

       --keepalive-time <seconds>
              This  option  sets the time a connection needs to remain idle before sending keepalive probes and the time between individual keepalive probes. It is currently effective on
              operating systems offering the TCP_KEEPIDLE and TCP_KEEPINTVL socket options (meaning Linux, recent AIX, HP-UX and more). This option has no  effect  if  --no-keepalive  is
              used. (Added in 7.18.0)

              If this option is used several times, the last one will be used. If unspecified, the option defaults to 60 seconds.

       --key <key>
              (SSL/SSH)  Private  key  file  name.  Allows you to provide your private key in this separate file. For SSH, if not specified, curl tries the following candidates in order:
              '~/.ssh/id_rsa', '~/.ssh/id_dsa', './id_rsa', './id_dsa'.

              If this option is used several times, the last one will be used.

       --key-type <type>
              (SSL) Private key file type. Specify which type your --key provided private key is. DER, PEM, and ENG are supported. If not specified, PEM is assumed.

              If this option is used several times, the last one will be used.

       --krb <level>
              (FTP) Enable Kerberos authentication and use. The level must be entered and should be one of 'clear', 'safe', 'confidential', or 'private'. Should you use a level  that  is
              not one of these, 'private' will instead be used.

              This option requires a library built with kerberos4 or GSSAPI (GSS-Negotiate) support. This is not very common. Use -V, --version to see if your curl supports it.

              If this option is used several times, the last one will be used.

       -l, --list-only
              (FTP)  When listing an FTP directory, this switch forces a name-only view.  Especially useful if you want to machine-parse the contents of an FTP directory since the normal
              directory view doesn't use a standard look or format.
              This option causes an FTP NLST command to be sent.  Some FTP servers list only files in their response to NLST; they do not include subdirectories and symbolic links.

       -L, --location
              (HTTP/HTTPS) If the 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. If used together with -i, --include or -I, --head, headers from all requested pages will be shown. When authentication is used,
              curl only sends its credentials to the initial host. If a redirect takes curl to a different host, it won't be able to intercept the  user+password.  See  also  --location-
              trusted on how to change this. You can limit the amount of redirects to follow by using the --max-redirs option.

              When curl follows a redirect and the request is not a plain GET (for example POST or PUT), it will do the following request with a GET if the HTTP response was 301, 302, or
              303. If the response code was any other 3xx code, curl will re-send the following request using the same unmodified method.

       --libcurl <file>
              Append this option to any ordinary curl command line, and you will get a libcurl-using C source code written to the file that does the equivalent of what your  command-line
              operation does!

              If this option is used several times, the last given file name will be used. (Added in 7.16.1)

       --limit-rate <speed>
              Specify the maximum transfer rate you want curl to use. This feature is useful if you have a limited pipe and you'd like your transfer not to use your entire bandwidth.

              The  given speed is measured in bytes/second, unless a suffix is appended.  Appending 'k' or 'K' will count the number as kilobytes, 'm' or M' makes it megabytes, while 'g'
              or 'G' makes it gigabytes. Examples: 200K, 3m and 1G.

              The given rate is the average speed counted during the entire transfer. It means that curl might use higher transfer speeds in short bursts, but over time it uses  no  more
              than the given rate.

              If you also use the -Y, --speed-limit option, that option will take precedence and might cripple the rate-limiting slightly, to help keeping the speed-limit logic working.

              If this option is used several times, the last one will be used.

       --local-port <num>[-num]
              Set  a  preferred  number or range of local port numbers to use for the connection(s).  Note that port numbers by nature are a scarce resource that will be busy at times so
              setting this range to something too narrow might cause unnecessary connection setup failures. (Added in 7.15.2)

       --location-trusted
              (HTTP/HTTPS) Like -L, --location, but will allow sending the name + password to all hosts that the site may redirect to. This may or may not introduce a security breach  if
              the site redirects you to a site to which you'll send your authentication info (which is plaintext in the case of HTTP Basic authentication).

       -m, --max-time <seconds>
              Maximum  time  in  seconds  that  you allow the whole operation to take.  This is useful for preventing your batch jobs from hanging for hours due to slow networks or links
              going down.  See also the --connect-timeout option.

              If this option is used several times, the last one will be used.
       --mail-auth <address>
              (SMTP) Specify a single address. This will be used to specify the authentication address (identity) of a submitted message that is being relayed to another server.

              (Added in 7.25.0)

       --mail-from <address>
              (SMTP) Specify a single address that the given mail should get sent from.

              (Added in 7.20.0)

       --max-filesize <bytes>
              Specify the maximum size (in bytes) of a file to download. If the file requested is larger than this value, the transfer will not start and curl will return with exit  code
              63.

              NOTE:  The  file  size  is  not  always known prior to download, and for such files this option has no effect even if the file transfer ends up being larger than this given
              limit. This concerns both FTP and HTTP transfers.

       --mail-rcpt <address>
              (SMTP) Specify a single address that the given mail should get sent to. This option can be used multiple times to specify many recipients.

              (Added in 7.20.0)

       --max-redirs <num>
              Set maximum number of redirection-followings allowed. If -L, --location is used, this option can be used to prevent curl  from  following  redirections  "in  absurdum".  By
              default, the limit is set to 50 redirections. Set this option to -1 to make it limitless.

              If this option is used several times, the last one will be used.

       --metalink
              This  option  can  tell curl to parse and process a given URI as Metalink file (both version 3 and 4 (RFC 5854) are supported) and make use of the mirrors listed within for
              failover if there are errors (such as the file or server not being available). It will also verify the hash of the file after the  download  completes.  The  Metalink  file
              itself is downloaded and processed in memory and not stored in the local file system.

              Example to use a remote Metalink file:

              curl --metalink http://www.example.com/example.metalink

              To use a Metalink file in the local file system, use FILE protocol (file://):

              curl --metalink file://example.metalink
              Please note that if FILE protocol is disabled, there is no way to use a local Metalink file at the time of this writing. Also note that if --metalink and --include are used
              together, --include will be ignored. This is because including headers in the response will break Metalink parser and if the headers are included in the file  described  in
              Metalink file, hash check will fail.

              (Added in 7.27.0, if built against the libmetalink library.)

       -n, --netrc
              Makes  curl  scan  the  .netrc (_netrc on Windows) file in the user's home directory for login name and password. This is typically used for FTP on UNIX. If used with HTTP,
              curl will enable user authentication. See netrc(4) or ftp(1) for details on the file format. Curl will not complain if that file doesn't  have  the  right  permissions  (it
              should not be either world- or group-readable). The environment variable "HOME" is used to find the home directory.

              A quick and very simple example of how to setup a .netrc to allow curl to FTP to the machine host.domain.com with user name 'myself' and password 'secret' should look simi‐
              lar to:

              machine host.domain.com login myself password secret

       -N, --no-buffer
              Disables the buffering of the output stream. In normal work situations, curl will use a standard buffered output stream that will have the effect that it  will  output  the
              data in chunks, not necessarily exactly when the data arrives.  Using this option will disable that buffering.

              Note that this is the negated option name documented. You can thus use --buffer to enforce the buffering.

       --netrc-file
              This  option is similar to --netrc, except that you provide the path (absolute or relative) to the netrc file that Curl should use.  You can only specify one netrc file per
              invocation. If several --netrc-file options are provided, only the last one will be used.  (Added in 7.21.5)

              This option overrides any use of --netrc as they are mutually exclusive.  It will also abide by --netrc-optional if specified.

       --netrc-optional
              Very similar to --netrc, but this option makes the .netrc usage optional and not mandatory as the --netrc option does.

       --negotiate
              (HTTP) Enables GSS-Negotiate authentication. The GSS-Negotiate method was designed by Microsoft and is used in their web applications. It is primarily meant  as  a  support
              for Kerberos5 authentication but may be also used along with another authentication method. For more information see IETF draft draft-brezak-spnego-http-04.txt.

              If you want to enable Negotiate for your proxy authentication, then use --proxy-negotiate.

              This option requires a library built with GSSAPI support. This is not very common. Use -V, --version to see if your version supports GSS-Negotiate.

              When  using  this option, you must also provide a fake -u, --user option to activate the authentication code properly. Sending a '-u :' is enough as the user name and pass‐
              word from the -u option aren't actually used.

              If this option is used several times, only the first one is used.
       --no-keepalive
              Disables the use of keepalive messages on the TCP connection, as by default curl enables them.

              Note that this is the negated option name documented. You can thus use --keepalive to enforce keepalive.

       --no-sessionid
              (SSL) Disable curl's use of SSL session-ID caching.  By default all transfers are done using the cache. Note that while nothing should ever get hurt by attempting to  reuse
              SSL session-IDs, there seem to be broken SSL implementations in the wild that may require you to disable this in order for you to succeed. (Added in 7.16.0)

              Note that this is the negated option name documented. You can thus use --sessionid to enforce session-ID caching.

       --noproxy <no-proxy-list>
              Comma-separated  list  of hosts which do not use a proxy, if one is specified.  The only wildcard is a single * character, which matches all hosts, and effectively disables
              the proxy. Each name in this list is matched as either a domain which contains the hostname,  or  the  hostname  itself.  For  example,  local.com  would  match  local.com,
              local.com:80, and www.local.com, but not www.notlocal.com.  (Added in 7.19.4).

       --ntlm (HTTP)  Enables  NTLM  authentication.  The NTLM authentication method was designed by Microsoft and is used by IIS web servers. It is a proprietary protocol, reverse-engi‐
              neered by clever people and implemented in curl based on their efforts. This kind of behavior should not be endorsed, you should encourage everyone who uses NTLM to  switch
              to a public and documented authentication method instead, such as Digest.

              If you want to enable NTLM for your proxy authentication, then use --proxy-ntlm.

              This option requires a library built with SSL support. Use -V, --version to see if your curl supports NTLM.

              If this option is used several times, only the first one is used.

       -o, --output <file>
              Write output to <file> instead of stdout. If you are using {} or [] to fetch multiple documents, you can use '#' followed by a number in the <file> specifier. That variable
              will be replaced with the current string for the URL being fetched. Like in:

                curl http://{one,two}.site.com -o "file_#1.txt"

              or use several variables like:

                curl http://{site,host}.host[1-5].com -o "#1_#2"

              You may use this option as many times as the number of URLs you have.

              See also the --create-dirs option to create the local directories dynamically. Specifying the output as '-' (a single dash) will force the output to be done to stdout.

       -O, --remote-name
              Write output to a local file named like the remote file we get. (Only the file part of the remote file is used, the path is cut off.)

              The remote file name to use for saving is extracted from the given URL, nothing else.
              Consequentially, the file will be saved in the current working directory. If you want the file saved in a different directory, make sure you change current  working  direc‐
              tory before you invoke curl with the -O, --remote-name flag!

              You may use this option as many times as the number of URLs you have.

       -p, --proxytunnel
              When an HTTP proxy is used (-x, --proxy), this option will cause non-HTTP protocols to attempt to tunnel through the proxy instead of merely using it to do HTTP-like opera‐
              tions. The tunnel approach is made with the HTTP proxy CONNECT request and requires that the proxy allows direct connect to the remote port  number  curl  wants  to  tunnel
              through to.

       -P, --ftp-port <address>
              (FTP)  Reverses  the  default  initiator/listener roles when connecting with FTP. This switch makes curl use active mode. In practice, curl then tells the server to connect
              back to the client's specified address and port, while passive mode asks the server to setup an IP address and port for it to connect to. <address> should be one of:

              interface
                     i.e "eth0" to specify which interface's IP address you want to use (Unix only)

              IP address
                     i.e "192.168.10.1" to specify the exact IP address

              host name
                     i.e "my.host.domain" to specify the machine

              -      make curl pick the same IP address that is already used for the control connection

       If this option is used several times, the last one will be used. Disable the use of PORT with --ftp-pasv. Disable the attempt to use the EPRT command  instead  of  PORT  by  using
       --disable-eprt. EPRT is really PORT++.

       Starting  in  7.19.5,  you can append ":[start]-[end]" to the right of the address, to tell curl what TCP port range to use. That means you specify a port range, from a lower to a
       higher number. A single number works as well, but do note that it increases the risk of failure since the port may not be available.

       --pass <phrase>
              (SSL/SSH) Passphrase for the private key

              If this option is used several times, the last one will be used.

       --post301
              (HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert POST requests into GET requests when following a 301 redirection. The non-RFC behaviour is  ubiquitous  in  web
              browsers,  so  curl  does  the conversion by default to maintain consistency. However, a server may require a POST to remain a POST after such a redirection. This option is
              meaningful only when using -L, --location (Added in 7.17.1)

       --post302
              (HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert POST requests into GET requests when following a 302 redirection. The non-RFC behaviour is  ubiquitous  in  web
              browsers,  so  curl  does  the conversion by default to maintain consistency. However, a server may require a POST to remain a POST after such a redirection. This option is
              meaningful only when using -L, --location (Added in 7.19.1)
       --post303
              (HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert POST requests into GET requests when following a 303 redirection. The non-RFC behaviour is  ubiquitous  in  web
              browsers,  so  curl  does  the conversion by default to maintain consistency. However, a server may require a POST to remain a POST after such a redirection. This option is
              meaningful only when using -L, --location (Added in 7.26.0)

       --proto <protocols>
              Tells curl to use the listed protocols for its initial retrieval. Protocols are evaluated left to right, are comma separated, and are each a protocol name or 'all', option‐
              ally prefixed by zero or more modifiers. Available modifiers are:

              +  Permit this protocol in addition to protocols already permitted (this is the default if no modifier is used).

              -  Deny this protocol, removing it from the list of protocols already permitted.

              =  Permit only this protocol (ignoring the list already permitted), though subject to later modification by subsequent entries in the comma separated list.

              For example:

              --proto -ftps  uses the default protocols, but disables ftps

              --proto -all,https,+http
                             only enables http and https

              --proto =http,https
                             also only enables http and https

              Unknown protocols produce a warning. This allows scripts to safely rely on being able to disable potentially dangerous protocols, without relying upon support for that pro‐
              tocol being built into curl to avoid an error.

              This option can be used multiple times, in which case the effect is the same as concatenating the protocols into one instance of the option.

              (Added in 7.20.2)

       --proto-redir <protocols>
              Tells curl to use the listed protocols after a redirect. See --proto for how protocols are represented.

              (Added in 7.20.2)

       --proxy-anyauth
              Tells curl to pick a suitable authentication method when communicating with the given proxy. This might cause an extra request/response round-trip. (Added in 7.13.2)

       --proxy-basic
              Tells curl to use HTTP Basic authentication when communicating with the given proxy. Use --basic for enabling HTTP Basic with a remote host. Basic is the default  authenti‐
              cation method curl uses with proxies.
       --proxy-digest
              Tells curl to use HTTP Digest authentication when communicating with the given proxy. Use --digest for enabling HTTP Digest with a remote host.

       --proxy-negotiate
              Tells curl to use HTTP Negotiate authentication when communicating with the given proxy. Use --negotiate for enabling HTTP Negotiate with a remote host. (Added in 7.17.1)

       --proxy-ntlm
              Tells curl to use HTTP NTLM authentication when communicating with the given proxy. Use --ntlm for enabling NTLM with a remote host.

       --proxy1.0 <proxyhost[:port]>
              Use the specified HTTP 1.0 proxy. If the port number is not specified, it is assumed at port 1080.

              The only difference between this and the HTTP proxy option (-x, --proxy), is that attempts to use CONNECT through the proxy will specify an HTTP 1.0 protocol instead of the
              default HTTP 1.1.

       --pubkey <key>
              (SSH) Public key file name. Allows you to provide your public key in this separate file.

              If this option is used several times, the last one will be used.

              (As of 7.39.0, curl attempts to automatically extract the public key from the private key file, so passing this option is generally not required. Note that this public  key
              extraction requires libcurl to be linked against a copy of libssh2 1.2.8 or higher that is itself linked against OpenSSL.)

       -q     If  used  as  the  first parameter on the command line, the curlrc config file will not be read and used. See the -K, --config for details on the default config file search
              path.

       -Q, --quote <command>
              (FTP/SFTP) Send an arbitrary command to the remote FTP or SFTP server. Quote commands are sent BEFORE the transfer takes place (just after the initial PWD command in an FTP
              transfer,  to  be exact). To make commands take place after a successful transfer, prefix them with a dash '-'.  To make commands be sent after curl has changed the working
              directory, just before the transfer command(s), prefix the command with a '+' (this is only supported for FTP). You may specify  any  number  of  commands.  If  the  server
              returns failure for one of the commands, the entire operation will be aborted. You must send syntactically correct FTP commands as RFC 959 defines to FTP servers, or one of
              the commands listed below to SFTP servers.  This option can be used multiple times. When speaking to an FTP server, prefix the command with an asterisk  (*)  to  make  curl
              continue even if the command fails as by default curl will stop at first failure.

              SFTP is a binary protocol. Unlike for FTP, curl interprets SFTP quote commands itself before sending them to the server.  File names may be quoted shell-style to embed spa‐
              ces or special characters.  Following is the list of all supported SFTP quote commands:

              chgrp group file
                     The chgrp command sets the group ID of the file named by the file operand to the group ID specified by the group operand. The group  operand  is  a  decimal  integer
                     group ID.

              chmod mode file
                     The chmod command modifies the file mode bits of the specified file. The mode operand is an octal integer mode number.

              chown user file
                     The chown command sets the owner of the file named by the file operand to the user ID specified by the user operand. The user operand is a decimal integer user ID.

              ln source_file target_file
                     The ln and symlink commands create a symbolic link at the target_file location pointing to the source_file location.

              mkdir directory_name
                     The mkdir command creates the directory named by the directory_name operand.

              pwd    The pwd command returns the absolute pathname of the current working directory.

              rename source target
                     The rename command renames the file or directory named by the source operand to the destination path named by the target operand.

              rm file
                     The rm command removes the file specified by the file operand.

              rmdir directory
                     The rmdir command removes the directory entry specified by the directory operand, provided it is empty.

              symlink source_file target_file
                     See ln.

       -r, --range <range>
              (HTTP/FTP/SFTP/FILE) Retrieve a byte range (i.e a partial document) from a HTTP/1.1, FTP or SFTP server or a local FILE. Ranges can be specified in a number of ways.

              0-499     specifies the first 500 bytes

              500-999   specifies the second 500 bytes

              -500      specifies the last 500 bytes

              9500-     specifies the bytes from offset 9500 and forward

              0-0,-1    specifies the first and last byte only(*)(H)

              500-700,600-799
                        specifies 300 bytes from offset 500(H)

              100-199,500-599
                        specifies two separate 100-byte ranges(*)(H)

       (*) = NOTE that this will cause the server to reply with a multipart response!

       Only digit characters (0-9) are valid in the 'start' and 'stop' fields of the 'start-stop' range syntax. If a non-digit character is given in the range, the server's response will
       be unspecified, depending on the server's configuration.
       You should also be aware that many HTTP/1.1 servers do not have this feature enabled, so that when you attempt to get a range, you'll instead get the whole document.

       FTP and SFTP range downloads only support the simple 'start-stop' syntax (optionally with one of the numbers omitted). FTP use depends on the extended FTP command SIZE.

       If this option is used several times, the last one will be used.

       -R, --remote-time
              When used, this will make curl attempt to figure out the timestamp of the remote file, and if that is available make the local file get that same timestamp.

       --random-file <file>
              (SSL) Specify the path name to file containing what will be considered as random data. The data is used to seed the random engine for SSL connections.  See also the  --egd-
              file option.

       --raw  (HTTP) When used, it disables all internal HTTP decoding of content or transfer encodings and instead makes them passed on unaltered, raw. (Added in 7.16.2)

       --remote-name-all
              This option changes the default action for all given URLs to be dealt with as if -O, --remote-name were used for each one. So if you want to disable that for a specific URL
              after --remote-name-all has been used, you must use "-o -" or --no-remote-name. (Added in 7.19.0)

       --resolve <host:port:address>
              Provide a custom address for a specific host and port pair. Using this, you can make the curl requests(s) use  a  specified  address  and  prevent  the  otherwise  normally
              resolved  address to be used. Consider it a sort of /etc/hosts alternative provided on the command line. The port number should be the number used for the specific protocol
              the host will be used for. It means you need several entries if you want to provide address for the same host but different ports.

              This option can be used many times to add many host names to resolve.

              (Added in 7.21.3)

       --retry <num>
              If a transient error is returned when curl tries to perform a transfer, it will retry this number of times before giving up. Setting the  number  to  0  makes  curl  do  no
              retries (which is the default). Transient error means either: a timeout, an FTP 4xx response code or an HTTP 5xx response code.

              When curl is about to retry a transfer, it will first wait one second and then for all forthcoming retries it will double the waiting time until it reaches 10 minutes which
              then