MANUAL
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上传日期:2018-10-23
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- LATEST VERSION
- You always find news about what's going on as well as the latest versions
- from the curl web pages, located at:
- http://curl.haxx.se
- SIMPLE USAGE
- Get the main page from Netscape's web-server:
- curl http://www.netscape.com/
- Get the README file the user's home directory at funet's ftp-server:
- curl ftp://ftp.funet.fi/README
- Get a web page from a server using port 8000:
- curl http://www.weirdserver.com:8000/
- Get a list of a directory of an FTP site:
- curl ftp://cool.haxx.se/
- Get the definition of curl from a dictionary:
- curl dict://dict.org/m:curl
- Fetch two documents at once:
- curl ftp://cool.haxx.se/ http://www.weirdserver.com:8000/
- Get a file off an FTPS server:
- curl ftps://files.are.secure.com/secrets.txt
- or use the more appropriate FTPS way to get the same file:
- curl --ftp-ssl ftp://files.are.secure.com/secrets.txt
- Get a file from an SSH server using SFTP:
- curl -u username sftp://shell.example.com/etc/issue
- Get a file from an SSH server using SCP using a private key to authenticate:
- curl -u username: --key ~/.ssh/id_dsa --pubkey ~/.ssh/id_dsa.pub
- scp://shell.example.com/~/personal.txt
- Get the main page from an IPv6 web server:
- curl -g "http://[2001:1890:1112:1::20]/"
- DOWNLOAD TO A FILE
- Get a web page and store in a local file:
- curl -o thatpage.html http://www.netscape.com/
- Get a web page and store in a local file, make the local file get the name
- of the remote document (if no file name part is specified in the URL, this
- will fail):
- curl -O http://www.netscape.com/index.html
- Fetch two files and store them with their remote names:
- curl -O www.haxx.se/index.html -O curl.haxx.se/download.html
- USING PASSWORDS
- FTP
- To ftp files using name+passwd, include them in the URL like:
- curl ftp://name:passwd@machine.domain:port/full/path/to/file
- or specify them with the -u flag like
- curl -u name:passwd ftp://machine.domain:port/full/path/to/file
- FTPS
- It is just like for FTP, but you may also want to specify and use
- SSL-specific options for certificates etc.
- Note that using FTPS:// as prefix is the "implicit" way as described in the
- standards while the recommended "explicit" way is done by using FTP:// and
- the --ftp-ssl option.
- SFTP / SCP
- This is similar to FTP, but you can specify a private key to use instead of
- a password. Note that the private key may itself be protected by a password
- that is unrelated to the login password of the remote system. If you
- provide a private key file you must also provide a public key file.
- HTTP
- Curl also supports user and password in HTTP URLs, thus you can pick a file
- like:
- curl http://name:passwd@machine.domain/full/path/to/file
- or specify user and password separately like in
- curl -u name:passwd http://machine.domain/full/path/to/file
- HTTP offers many different methods of authentication and curl supports
- several: Basic, Digest, NTLM and Negotiate. Without telling which method to
- use, curl defaults to Basic. You can also ask curl to pick the most secure
- ones out of the ones that the server accepts for the given URL, by using
- --anyauth.
- NOTE! Since HTTP URLs don't support user and password, you can't use that
- style when using Curl via a proxy. You _must_ use the -u style fetch
- during such circumstances.
- HTTPS
- Probably most commonly used with private certificates, as explained below.
- PROXY
- Get an ftp file using a proxy named my-proxy that uses port 888:
- curl -x my-proxy:888 ftp://ftp.leachsite.com/README
- Get a file from a HTTP server that requires user and password, using the
- same proxy as above:
- curl -u user:passwd -x my-proxy:888 http://www.get.this/
- Some proxies require special authentication. Specify by using -U as above:
- curl -U user:passwd -x my-proxy:888 http://www.get.this/
- curl also supports SOCKS4 and SOCKS5 proxies with --socks4 and --socks5.
- See also the environment variables Curl support that offer further proxy
- control.
- RANGES
- With HTTP 1.1 byte-ranges were introduced. Using this, a client can request
- to get only one or more subparts of a specified document. Curl supports
- this with the -r flag.
- Get the first 100 bytes of a document:
- curl -r 0-99 http://www.get.this/
- Get the last 500 bytes of a document:
- curl -r -500 http://www.get.this/
- Curl also supports simple ranges for FTP files as well. Then you can only
- specify start and stop position.
- Get the first 100 bytes of a document using FTP:
- curl -r 0-99 ftp://www.get.this/README
- UPLOADING
- FTP / FTPS / SFTP / SCP
- Upload all data on stdin to a specified server:
- curl -T - ftp://ftp.upload.com/myfile
- Upload data from a specified file, login with user and password:
- curl -T uploadfile -u user:passwd ftp://ftp.upload.com/myfile
- Upload a local file to the remote site, and use the local file name remote
- too:
-
- curl -T uploadfile -u user:passwd ftp://ftp.upload.com/
- Upload a local file to get appended to the remote file:
- curl -T localfile -a ftp://ftp.upload.com/remotefile
- Curl also supports ftp upload through a proxy, but only if the proxy is
- configured to allow that kind of tunneling. If it does, you can run curl in
- a fashion similar to:
- curl --proxytunnel -x proxy:port -T localfile ftp.upload.com
- HTTP
- Upload all data on stdin to a specified http site:
- curl -T - http://www.upload.com/myfile
- Note that the http server must have been configured to accept PUT before
- this can be done successfully.
- For other ways to do http data upload, see the POST section below.
- VERBOSE / DEBUG
- If curl fails where it isn't supposed to, if the servers don't let you in,
- if you can't understand the responses: use the -v flag to get verbose
- fetching. Curl will output lots of info and what it sends and receives in
- order to let the user see all client-server interaction (but it won't show
- you the actual data).
- curl -v ftp://ftp.upload.com/
- To get even more details and information on what curl does, try using the
- --trace or --trace-ascii options with a given file name to log to, like
- this:
- curl --trace trace.txt www.haxx.se
-
- DETAILED INFORMATION
- Different protocols provide different ways of getting detailed information
- about specific files/documents. To get curl to show detailed information
- about a single file, you should use -I/--head option. It displays all
- available info on a single file for HTTP and FTP. The HTTP information is a
- lot more extensive.
- For HTTP, you can get the header information (the same as -I would show)
- shown before the data by using -i/--include. Curl understands the
- -D/--dump-header option when getting files from both FTP and HTTP, and it
- will then store the headers in the specified file.
- Store the HTTP headers in a separate file (headers.txt in the example):
- curl --dump-header headers.txt curl.haxx.se
- Note that headers stored in a separate file can be very useful at a later
- time if you want curl to use cookies sent by the server. More about that in
- the cookies section.
- POST (HTTP)
- It's easy to post data using curl. This is done using the -d <data>
- option. The post data must be urlencoded.
- Post a simple "name" and "phone" guestbook.
- curl -d "name=Rafael%20Sagula&phone=3320780"
- http://www.where.com/guest.cgi
- How to post a form with curl, lesson #1:
- Dig out all the <input> tags in the form that you want to fill in. (There's
- a perl program called formfind.pl on the curl site that helps with this).
- If there's a "normal" post, you use -d to post. -d takes a full "post
- string", which is in the format
- <variable1>=<data1>&<variable2>=<data2>&...
- The 'variable' names are the names set with "name=" in the <input> tags, and
- the data is the contents you want to fill in for the inputs. The data *must*
- be properly URL encoded. That means you replace space with + and that you
- write weird letters with %XX where XX is the hexadecimal representation of
- the letter's ASCII code.
- Example:
- (page located at http://www.formpost.com/getthis/
- <form action="post.cgi" method="post">
- <input name=user size=10>
- <input name=pass type=password size=10>
- <input name=id type=hidden value="blablabla">
- <input name=ding value="submit">
- </form>
- We want to enter user 'foobar' with password '12345'.
- To post to this, you enter a curl command line like:
- curl -d "user=foobar&pass=12345&id=blablabla&ding=submit" (continues)
- http://www.formpost.com/getthis/post.cgi
- While -d uses the application/x-www-form-urlencoded mime-type, generally
- understood by CGI's and similar, curl also supports the more capable
- multipart/form-data type. This latter type supports things like file upload.
- -F accepts parameters like -F "name=contents". If you want the contents to
- be read from a file, use <@filename> as contents. When specifying a file,
- you can also specify the file content type by appending ';type=<mime type>'
- to the file name. You can also post the contents of several files in one
- field. For example, the field name 'coolfiles' is used to send three files,
- with different content types using the following syntax:
- curl -F "coolfiles=@fil1.gif;type=image/gif,fil2.txt,fil3.html"
- http://www.post.com/postit.cgi
- If the content-type is not specified, curl will try to guess from the file
- extension (it only knows a few), or use the previously specified type (from
- an earlier file if several files are specified in a list) or else it will
- using the default type 'text/plain'.
- Emulate a fill-in form with -F. Let's say you fill in three fields in a
- form. One field is a file name which to post, one field is your name and one
- field is a file description. We want to post the file we have written named
- "cooltext.txt". To let curl do the posting of this data instead of your
- favourite browser, you have to read the HTML source of the form page and
- find the names of the input fields. In our example, the input field names
- are 'file', 'yourname' and 'filedescription'.
- curl -F "file=@cooltext.txt" -F "yourname=Daniel"
- -F "filedescription=Cool text file with cool text inside"
- http://www.post.com/postit.cgi
- To send two files in one post you can do it in two ways:
- 1. Send multiple files in a single "field" with a single field name:
-
- curl -F "pictures=@dog.gif,cat.gif"
-
- 2. Send two fields with two field names:
- curl -F "docpicture=@dog.gif" -F "catpicture=@cat.gif"
- To send a field value literally without interpreting a leading '@'
- or '<', or an embedded ';type=', use --form-string instead of
- -F. This is recommended when the value is obtained from a user or
- some other unpredictable source. Under these circumstances, using
- -F instead of --form-string would allow a user to trick curl into
- uploading a file.
- REFERRER
- A HTTP request has the option to include information about which address
- that referred to actual page. Curl allows you to specify the
- referrer to be used on the command line. It is especially useful to
- fool or trick stupid servers or CGI scripts that rely on that information
- being available or contain certain data.
- curl -e www.coolsite.com http://www.showme.com/
- NOTE: The Referer: [sic] field is defined in the HTTP spec to be a full URL.
- USER AGENT
- A HTTP request has the option to include information about the browser
- that generated the request. Curl allows it to be specified on the command
- line. It is especially useful to fool or trick stupid servers or CGI
- scripts that only accept certain browsers.
- Example:
- curl -A 'Mozilla/3.0 (Win95; I)' http://www.nationsbank.com/
- Other common strings:
- 'Mozilla/3.0 (Win95; I)' Netscape Version 3 for Windows 95
- 'Mozilla/3.04 (Win95; U)' Netscape Version 3 for Windows 95
- 'Mozilla/2.02 (OS/2; U)' Netscape Version 2 for OS/2
- 'Mozilla/4.04 [en] (X11; U; AIX 4.2; Nav)' NS for AIX
- 'Mozilla/4.05 [en] (X11; U; Linux 2.0.32 i586)' NS for Linux
- Note that Internet Explorer tries hard to be compatible in every way:
- 'Mozilla/4.0 (compatible; MSIE 4.01; Windows 95)' MSIE for W95
- Mozilla is not the only possible User-Agent name:
- 'Konqueror/1.0' KDE File Manager desktop client
- 'Lynx/2.7.1 libwww-FM/2.14' Lynx command line browser
- COOKIES
- Cookies are generally used by web servers to keep state information at the
- client's side. The server sets cookies by sending a response line in the
- headers that looks like 'Set-Cookie: <data>' where the data part then
- typically contains a set of NAME=VALUE pairs (separated by semicolons ';'
- like "NAME1=VALUE1; NAME2=VALUE2;"). The server can also specify for what
- path the "cookie" should be used for (by specifying "path=value"), when the
- cookie should expire ("expire=DATE"), for what domain to use it
- ("domain=NAME") and if it should be used on secure connections only
- ("secure").
- If you've received a page from a server that contains a header like:
- Set-Cookie: sessionid=boo123; path="/foo";
- it means the server wants that first pair passed on when we get anything in
- a path beginning with "/foo".
- Example, get a page that wants my name passed in a cookie:
- curl -b "name=Daniel" www.sillypage.com
- Curl also has the ability to use previously received cookies in following
- sessions. If you get cookies from a server and store them in a file in a
- manner similar to:
- curl --dump-header headers www.example.com
- ... you can then in a second connect to that (or another) site, use the
- cookies from the 'headers' file like:
- curl -b headers www.example.com
- While saving headers to a file is a working way to store cookies, it is
- however error-prone and not the preferred way to do this. Instead, make curl
- save the incoming cookies using the well-known netscape cookie format like
- this:
- curl -c cookies.txt www.example.com
- Note that by specifying -b you enable the "cookie awareness" and with -L
- you can make curl follow a location: (which often is used in combination
- with cookies). So that if a site sends cookies and a location, you can
- use a non-existing file to trigger the cookie awareness like:
- curl -L -b empty.txt www.example.com
- The file to read cookies from must be formatted using plain HTTP headers OR
- as netscape's cookie file. Curl will determine what kind it is based on the
- file contents. In the above command, curl will parse the header and store
- the cookies received from www.example.com. curl will send to the server the
- stored cookies which match the request as it follows the location. The
- file "empty.txt" may be a nonexistent file.
- Alas, to both read and write cookies from a netscape cookie file, you can
- set both -b and -c to use the same file:
- curl -b cookies.txt -c cookies.txt www.example.com
- PROGRESS METER
- The progress meter exists to show a user that something actually is
- happening. The different fields in the output have the following meaning:
- % Total % Received % Xferd Average Speed Time Curr.
- Dload Upload Total Current Left Speed
- 0 151M 0 38608 0 0 9406 0 4:41:43 0:00:04 4:41:39 9287
- From left-to-right:
- % - percentage completed of the whole transfer
- Total - total size of the whole expected transfer
- % - percentage completed of the download
- Received - currently downloaded amount of bytes
- % - percentage completed of the upload
- Xferd - currently uploaded amount of bytes
- Average Speed
- Dload - the average transfer speed of the download
- Average Speed
- Upload - the average transfer speed of the upload
- Time Total - expected time to complete the operation
- Time Current - time passed since the invoke
- Time Left - expected time left to completion
- Curr.Speed - the average transfer speed the last 5 seconds (the first
- 5 seconds of a transfer is based on less time of course.)
- The -# option will display a totally different progress bar that doesn't
- need much explanation!
- SPEED LIMIT
- Curl allows the user to set the transfer speed conditions that must be met
- to let the transfer keep going. By using the switch -y and -Y you
- can make curl abort transfers if the transfer speed is below the specified
- lowest limit for a specified time.
- To have curl abort the download if the speed is slower than 3000 bytes per
- second for 1 minute, run:
- curl -Y 3000 -y 60 www.far-away-site.com
- This can very well be used in combination with the overall time limit, so
- that the above operation must be completed in whole within 30 minutes:
- curl -m 1800 -Y 3000 -y 60 www.far-away-site.com
- Forcing curl not to transfer data faster than a given rate is also possible,
- which might be useful if you're using a limited bandwidth connection and you
- don't want your transfer to use all of it (sometimes referred to as
- "bandwidth throttle").
- Make curl transfer data no faster than 10 kilobytes per second:
- curl --limit-rate 10K www.far-away-site.com
- or
- curl --limit-rate 10240 www.far-away-site.com
- Or prevent curl from uploading data faster than 1 megabyte per second:
- curl -T upload --limit-rate 1M ftp://uploadshereplease.com
- When using the --limit-rate option, the transfer rate is regulated on a
- per-second basis, which will cause the total transfer speed to become lower
- than the given number. Sometimes of course substantially lower, if your
- transfer stalls during periods.
- CONFIG FILE
- Curl automatically tries to read the .curlrc file (or _curlrc file on win32
- systems) from the user's home dir on startup.
- The config file could be made up with normal command line switches, but you
- can also specify the long options without the dashes to make it more
- readable. You can separate the options and the parameter with spaces, or
- with = or :. Comments can be used within the file. If the first letter on a
- line is a '#'-letter the rest of the line is treated as a comment.
- If you want the parameter to contain spaces, you must enclose the entire
- parameter within double quotes ("). Within those quotes, you specify a
- quote as ".
- NOTE: You must specify options and their arguments on the same line.
- Example, set default time out and proxy in a config file:
- # We want a 30 minute timeout:
- -m 1800
- # ... and we use a proxy for all accesses:
- proxy = proxy.our.domain.com:8080
- White spaces ARE significant at the end of lines, but all white spaces
- leading up to the first characters of each line are ignored.
- Prevent curl from reading the default file by using -q as the first command
- line parameter, like:
- curl -q www.thatsite.com
- Force curl to get and display a local help page in case it is invoked
- without URL by making a config file similar to:
- # default url to get
- url = "http://help.with.curl.com/curlhelp.html"
- You can specify another config file to be read by using the -K/--config
- flag. If you set config file name to "-" it'll read the config from stdin,
- which can be handy if you want to hide options from being visible in process
- tables etc:
- echo "user = user:passwd" | curl -K - http://that.secret.site.com
- EXTRA HEADERS
- When using curl in your own very special programs, you may end up needing
- to pass on your own custom headers when getting a web page. You can do
- this by using the -H flag.
- Example, send the header "X-you-and-me: yes" to the server when getting a
- page:
- curl -H "X-you-and-me: yes" www.love.com
- This can also be useful in case you want curl to send a different text in a
- header than it normally does. The -H header you specify then replaces the
- header curl would normally send. If you replace an internal header with an
- empty one, you prevent that header from being sent. To prevent the Host:
- header from being used:
- curl -H "Host:" www.server.com
- FTP and PATH NAMES
- Do note that when getting files with the ftp:// URL, the given path is
- relative the directory you enter. To get the file 'README' from your home
- directory at your ftp site, do:
- curl ftp://user:passwd@my.site.com/README
- But if you want the README file from the root directory of that very same
- site, you need to specify the absolute file name:
- curl ftp://user:passwd@my.site.com//README
- (I.e with an extra slash in front of the file name.)
- SFTP and SCP and PATH NAMES
- With sftp: and scp: URLs, the path name given is the absolute name on the
- server. To access a file relative to the remote user's home directory,
- prefix the file with /~/ , such as:
- curl -u $USER sftp://home.example.com/~/.bashrc
- FTP and firewalls
- The FTP protocol requires one of the involved parties to open a second
- connection as soon as data is about to get transfered. There are two ways to
- do this.
- The default way for curl is to issue the PASV command which causes the
- server to open another port and await another connection performed by the
- client. This is good if the client is behind a firewall that don't allow
- incoming connections.
- curl ftp.download.com
- If the server for example, is behind a firewall that don't allow connections
- on other ports than 21 (or if it just doesn't support the PASV command), the
- other way to do it is to use the PORT command and instruct the server to
- connect to the client on the given (as parameters to the PORT command) IP
- number and port.
- The -P flag to curl supports a few different options. Your machine may have
- several IP-addresses and/or network interfaces and curl allows you to select
- which of them to use. Default address can also be used:
- curl -P - ftp.download.com
- Download with PORT but use the IP address of our 'le0' interface (this does
- not work on windows):
- curl -P le0 ftp.download.com
- Download with PORT but use 192.168.0.10 as our IP address to use:
- curl -P 192.168.0.10 ftp.download.com
- NETWORK INTERFACE
- Get a web page from a server using a specified port for the interface:
- curl --interface eth0:1 http://www.netscape.com/
- or
- curl --interface 192.168.1.10 http://www.netscape.com/
- HTTPS
- Secure HTTP requires SSL libraries to be installed and used when curl is
- built. If that is done, curl is capable of retrieving and posting documents
- using the HTTPS protocol.
- Example:
- curl https://www.secure-site.com
- Curl is also capable of using your personal certificates to get/post files
- from sites that require valid certificates. The only drawback is that the
- certificate needs to be in PEM-format. PEM is a standard and open format to
- store certificates with, but it is not used by the most commonly used
- browsers (Netscape and MSIE both use the so called PKCS#12 format). If you
- want curl to use the certificates you use with your (favourite) browser, you
- may need to download/compile a converter that can convert your browser's
- formatted certificates to PEM formatted ones. This kind of converter is
- included in recent versions of OpenSSL, and for older versions Dr Stephen
- N. Henson has written a patch for SSLeay that adds this functionality. You
- can get his patch (that requires an SSLeay installation) from his site at:
- http://www.drh-consultancy.demon.co.uk/
- Example on how to automatically retrieve a document using a certificate with
- a personal password:
- curl -E /path/to/cert.pem:password https://secure.site.com/
- If you neglect to specify the password on the command line, you will be
- prompted for the correct password before any data can be received.
- Many older SSL-servers have problems with SSLv3 or TLS, that newer versions
- of OpenSSL etc is using, therefore it is sometimes useful to specify what
- SSL-version curl should use. Use -3, -2 or -1 to specify that exact SSL
- version to use (for SSLv3, SSLv2 or TLSv1 respectively):
- curl -2 https://secure.site.com/
- Otherwise, curl will first attempt to use v3 and then v2.
- To use OpenSSL to convert your favourite browser's certificate into a PEM
- formatted one that curl can use, do something like this (assuming netscape,
- but IE is likely to work similarly):
- You start with hitting the 'security' menu button in netscape.
- Select 'certificates->yours' and then pick a certificate in the list
- Press the 'export' button
- enter your PIN code for the certs
- select a proper place to save it
- Run the 'openssl' application to convert the certificate. If you cd to the
- openssl installation, you can do it like:
- # ./apps/openssl pkcs12 -in [file you saved] -clcerts -out [PEMfile]
- RESUMING FILE TRANSFERS
- To continue a file transfer where it was previously aborted, curl supports
- resume on http(s) downloads as well as ftp uploads and downloads.
- Continue downloading a document:
- curl -C - -o file ftp://ftp.server.com/path/file
- Continue uploading a document(*1):
- curl -C - -T file ftp://ftp.server.com/path/file
- Continue downloading a document from a web server(*2):
- curl -C - -o file http://www.server.com/
- (*1) = This requires that the ftp server supports the non-standard command
- SIZE. If it doesn't, curl will say so.
- (*2) = This requires that the web server supports at least HTTP/1.1. If it
- doesn't, curl will say so.
- TIME CONDITIONS
- HTTP allows a client to specify a time condition for the document it
- requests. It is If-Modified-Since or If-Unmodified-Since. Curl allow you to
- specify them with the -z/--time-cond flag.
- For example, you can easily make a download that only gets performed if the
- remote file is newer than a local copy. It would be made like:
- curl -z local.html http://remote.server.com/remote.html
- Or you can download a file only if the local file is newer than the remote
- one. Do this by prepending the date string with a '-', as in:
- curl -z -local.html http://remote.server.com/remote.html
- You can specify a "free text" date as condition. Tell curl to only download
- the file if it was updated since January 12, 2012:
- curl -z "Jan 12 2012" http://remote.server.com/remote.html
- Curl will then accept a wide range of date formats. You always make the date
- check the other way around by prepending it with a dash '-'.
- DICT
- For fun try
- curl dict://dict.org/m:curl
- curl dict://dict.org/d:heisenbug:jargon
- curl dict://dict.org/d:daniel:web1913
- Aliases for 'm' are 'match' and 'find', and aliases for 'd' are 'define'
- and 'lookup'. For example,
- curl dict://dict.org/find:curl
- Commands that break the URL description of the RFC (but not the DICT
- protocol) are
- curl dict://dict.org/show:db
- curl dict://dict.org/show:strat
- Authentication is still missing (but this is not required by the RFC)
- LDAP
- If you have installed the OpenLDAP library, curl can take advantage of it
- and offer ldap:// support.
- LDAP is a complex thing and writing an LDAP query is not an easy task. I do
- advice you to dig up the syntax description for that elsewhere. Two places
- that might suit you are:
- Netscape's "Netscape Directory SDK 3.0 for C Programmer's Guide Chapter 10:
- Working with LDAP URLs":
- http://developer.netscape.com/docs/manuals/dirsdk/csdk30/url.htm
- RFC 2255, "The LDAP URL Format" http://curl.haxx.se/rfc/rfc2255.txt
- To show you an example, this is now I can get all people from my local LDAP
- server that has a certain sub-domain in their email address:
- curl -B "ldap://ldap.frontec.se/o=frontec??sub?mail=*sth.frontec.se"
- If I want the same info in HTML format, I can get it by not using the -B
- (enforce ASCII) flag.
- ENVIRONMENT VARIABLES
- Curl reads and understands the following environment variables:
- http_proxy, HTTPS_PROXY, FTP_PROXY
- They should be set for protocol-specific proxies. General proxy should be
- set with
-
- ALL_PROXY
- A comma-separated list of host names that shouldn't go through any proxy is
- set in (only an asterisk, '*' matches all hosts)
- NO_PROXY
- If a tail substring of the domain-path for a host matches one of these
- strings, transactions with that node will not be proxied.
- The usage of the -x/--proxy flag overrides the environment variables.
- NETRC
- Unix introduced the .netrc concept a long time ago. It is a way for a user
- to specify name and password for commonly visited ftp sites in a file so
- that you don't have to type them in each time you visit those sites. You
- realize this is a big security risk if someone else gets hold of your
- passwords, so therefore most unix programs won't read this file unless it is
- only readable by yourself (curl doesn't care though).
- Curl supports .netrc files if told so (using the -n/--netrc and
- --netrc-optional options). This is not restricted to only ftp,
- but curl can use it for all protocols where authentication is used.
- A very simple .netrc file could look something like:
- machine curl.haxx.se login iamdaniel password mysecret
- CUSTOM OUTPUT
- To better allow script programmers to get to know about the progress of
- curl, the -w/--write-out option was introduced. Using this, you can specify
- what information from the previous transfer you want to extract.
- To display the amount of bytes downloaded together with some text and an
- ending newline:
- curl -w 'We downloaded %{size_download} bytesn' www.download.com
- KERBEROS FTP TRANSFER
- Curl supports kerberos4 and kerberos5/GSSAPI for FTP transfers. You need
- the kerberos package installed and used at curl build time for it to be
- used.
- First, get the krb-ticket the normal way, like with the kinit/kauth tool.
- Then use curl in way similar to:
- curl --krb private ftp://krb4site.com -u username:fakepwd
- There's no use for a password on the -u switch, but a blank one will make
- curl ask for one and you already entered the real password to kinit/kauth.
- TELNET
- The curl telnet support is basic and very easy to use. Curl passes all data
- passed to it on stdin to the remote server. Connect to a remote telnet
- server using a command line similar to:
- curl telnet://remote.server.com
- And enter the data to pass to the server on stdin. The result will be sent
- to stdout or to the file you specify with -o.
- You might want the -N/--no-buffer option to switch off the buffered output
- for slow connections or similar.
- Pass options to the telnet protocol negotiation, by using the -t option. To
- tell the server we use a vt100 terminal, try something like:
- curl -tTTYPE=vt100 telnet://remote.server.com
- Other interesting options for it -t include:
- - XDISPLOC=<X display> Sets the X display location.
- - NEW_ENV=<var,val> Sets an environment variable.
- NOTE: the telnet protocol does not specify any way to login with a specified
- user and password so curl can't do that automatically. To do that, you need
- to track when the login prompt is received and send the username and
- password accordingly.
- PERSISTENT CONNECTIONS
- Specifying multiple files on a single command line will make curl transfer
- all of them, one after the other in the specified order.
- libcurl will attempt to use persistent connections for the transfers so that
- the second transfer to the same host can use the same connection that was
- already initiated and was left open in the previous transfer. This greatly
- decreases connection time for all but the first transfer and it makes a far
- better use of the network.
- Note that curl cannot use persistent connections for transfers that are used
- in subsequence curl invokes. Try to stuff as many URLs as possible on the
- same command line if they are using the same host, as that'll make the
- transfers faster. If you use a http proxy for file transfers, practically
- all transfers will be persistent.
- MULTIPLE TRANSFERS WITH A SINGLE COMMAND LINE
- As is mentioned above, you can download multiple files with one command line
- by simply adding more URLs. If you want those to get saved to a local file
- instead of just printed to stdout, you need to add one save option for each
- URL you specify. Note that this also goes for the -O option (but not
- --remote-name-all).
- For example: get two files and use -O for the first and a custom file
- name for the second:
- curl -O http://url.com/file.txt ftp://ftp.com/moo.exe -o moo.jpg
- You can also upload multiple files in a similar fashion:
- curl -T local1 ftp://ftp.com/moo.exe -T local2 ftp://ftp.com/moo2.txt
- IPv6
- curl will connect to a server with IPv6 when a host lookup returns an IPv6
- address and fall back to IPv4 if the connection fails. The --ipv4 and --ipv6
- options can specify which address to use when both are available. IPv6
- addresses can also be specified directly in URLs using the syntax:
- http://[2001:1890:1112:1::20]/overview.html
- When this style is used, the -g option must be given to stop curl from
- interpreting the square brackets as special globbing characters. Link local
- and site local addresses including a scope identifier, such as fe80::1234%1,
- may also be used, but the scope portion must be numeric and the percent
- character must be URL escaped. The previous example in an SFTP URL might
- look like:
- sftp://[fe80::1234%251]/
- IPv6 addresses provided other than in URLs (e.g. to the --proxy, --interface
- or --ftp-port options) should not be URL encoded.
- MAILING LISTS
- For your convenience, we have several open mailing lists to discuss curl,
- its development and things relevant to this. Get all info at
- http://curl.haxx.se/mail/. Some of the lists available are:
- curl-users
- Users of the command line tool. How to use it, what doesn't work, new
- features, related tools, questions, news, installations, compilations,
- running, porting etc.
- curl-library
- Developers using or developing libcurl. Bugs, extensions, improvements.
- curl-announce
- Low-traffic. Only receives announcements of new public versions. At worst,
- that makes something like one or two mails per month, but usually only one
- mail every second month.
- curl-and-php
- Using the curl functions in PHP. Everything curl with a PHP angle. Or PHP
- with a curl angle.
- curl-and-python
- Python hackers using curl with or without the python binding pycurl.
- Please direct curl questions, feature requests and trouble reports to one of
- these mailing lists instead of mailing any individual.