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diff --git a/docs/MANUAL.md b/docs/MANUAL.md new file mode 100644 index 000000000..80ab92a63 --- /dev/null +++ b/docs/MANUAL.md @@ -0,0 +1,1011 @@ +# curl tutorial + +## 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 directory listing 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://example.com/etc/issue + +Get a file from an SSH server using SCP using a private key (not +password-protected) to authenticate: + + curl -u username: --key ~/.ssh/id_rsa scp://example.com/~/file.txt + +Get a file from an SSH server using SCP using a private key +(password-protected) to authenticate: + + curl -u username: --key ~/.ssh/id_rsa --pass private_key_password + scp://example.com/~/file.txt + +Get the main page from an IPv6 web server: + + curl "http://[2001:1890:1112:1::20]/" + +Get a file from an SMB server: + + curl -u "domain\username:passwd" smb://server.example.com/share/file.txt + +## Download to a File + +Get a web page and store in a local file with a specific name: + + 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 use the `--key` option to 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; this password is specified using the `--pass` option. +Typically, curl will automatically extract the public key from the private key +file, but in cases where curl does not have the proper library support, a +matching public key file must be specified using the `--pubkey` option. + +### 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 (SPNEGO). 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**! According to the URL specification, HTTP URLs can not contain a user +and password, so that style will not work when using curl via a proxy, even +though curl allows it at other times. When using a proxy, you _must_ use the +`-u` style for user and password. + +### HTTPS + +Probably most commonly used with private certificates, as explained below. + +## Proxy + +curl supports both HTTP and SOCKS proxy servers, with optional authentication. +It does not have special support for FTP proxy servers since there are no +standards for those, but it can still be made to work with many of them. You +can also use both HTTP and SOCKS proxies to transfer files to and from FTP +servers. + +Get an ftp file using an HTTP proxy named my-proxy that uses port 888: + + curl -x my-proxy:888 ftp://ftp.leachsite.com/README + +Get a file from an 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/ + +A comma-separated list of hosts and domains which do not use the proxy can be +specified as: + + curl --noproxy localhost,get.this -x my-proxy:888 http://www.get.this/ + +If the proxy is specified with `--proxy1.0` instead of `--proxy` or `-x`, then +curl will use HTTP/1.0 instead of HTTP/1.1 for any `CONNECT` attempts. + +curl also supports SOCKS4 and SOCKS5 proxies with `--socks4` and `--socks5`. + +See also the environment variables Curl supports that offer further proxy +control. + +Most FTP proxy servers are set up to appear as a normal FTP server from the +client's perspective, with special commands to select the remote FTP server. +curl supports the `-u`, `-Q` and `--ftp-account` options that can be used to +set up transfers through many FTP proxies. For example, a file can be uploaded +to a remote FTP server using a Blue Coat FTP proxy with the options: + + curl -u "username@ftp.server Proxy-Username:Remote-Pass" + --ftp-account Proxy-Password --upload-file local-file + ftp://my-ftp.proxy.server:21/remote/upload/path/ + +See the manual for your FTP proxy to determine the form it expects to set up +transfers, and curl's `-v` option to see exactly what curl is sending. + +## Ranges + +HTTP 1.1 introduced byte-ranges. 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 at the +remote site 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 + +### SMB / SMBS + + curl -T file.txt -u "domain\username:passwd" + smb://server.example.com/share/ + +### 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. + +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 replace 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" + 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 use the +default type 'application/octet-stream'. + +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: + +Send multiple files in a single "field" with a single field name: + + curl -F "pictures=@dog.gif,cat.gif" $URL + +Send two fields with two field names + + curl -F "docpicture=@dog.gif" -F "catpicture=@cat.gif" $URL + +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` could +allow a user to trick curl into uploading a file. + +## Referrer + +An HTTP request has the option to include information about which address +referred it to the 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/ + +## User Agent + +An 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)` - Netscape for AIX +- `Mozilla/4.05 [en] (X11; U; Linux 2.0.32 i586)` - Netscape 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. + +To 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 +Microsoft Windows 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 `#`-symbol 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 a `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 transferred. 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 doesn't allow +incoming connections. + + curl ftp.download.com + +If the server, for example, is behind a firewall that doesn't allow +connections on ports other 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 IP number and port (as parameters +to the PORT command). + +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 a TLS library 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 client 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. 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. + +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 HTTPS servers have problems with specific SSL or TLS versions, +which newer versions of OpenSSL etc use, 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 attempt to use a sensible TLS default version. + +## Resuming File Transfers + +To continue a file transfer where it was previously aborted, curl supports +esume 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: + + curl -C - -T file ftp://ftp.server.com/path/file + +Continue downloading a document from a web server + + curl -C - -o file http://www.server.com/ + +## 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 allows 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 support is still missing + +## LDAP + +If you have installed the OpenLDAP library, curl can take advantage of it and +offer `ldap://` support. On Windows, curl will use WinLDAP from Platform SDK +by default. + +Default protocol version used by curl is LDAPv3. LDAPv2 will be used as +fallback mechanism in case if LDAPv3 will fail to connect. + +LDAP is a complex thing and writing an LDAP query is not an easy task. I do +advise you to dig up the syntax description for that elsewhere. One such place +might be: [RFC 2255, The LDAP URL +Format](https://curl.haxx.se/rfc/rfc2255.txt) + +To show you an example, this is how 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. + +You also can use authentication when accessing LDAP catalog: + + curl -u user:passwd "ldap://ldap.frontec.se/o=frontec??sub?mail=*" + curl "ldap://user:passwd@ldap.frontec.se/o=frontec??sub?mail=*" + +By default, if user and password provided, OpenLDAP/WinLDAP will use basic +authentication. On Windows you can control this behavior by providing one of +`--basic`, `--ntlm` or `--digest` option in curl command line + + curl --ntlm "ldap://user:passwd@ldap.frontec.se/o=frontec??sub?mail=*" + +On Windows, if no user/password specified, auto-negotiation mechanism will be +used with current logon credentials (SSPI/SPNEGO). + +## 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 the host name matches one of these strings, or the host is within the +domain of one of these strings, transactions with that node will not be +proxied. When a domain is used, it needs to start with a period. A user can +specify that both www.example.com and foo.example.com should not use a proxy +by setting `NO_PROXY` to `.example.com`. By including the full name you can +exclude specific host names, so to make `www.example.com` not use a proxy but +still have `foo.example.com` do it, set `NO_PROXY` to `www.example.com`. + +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 to (using the `-n`/`--netrc` and +`--netrc-optional` options). This is not restricted to just FTP, so 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} bytes\n' 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 available. + +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 an 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 or match an existing +network interface on Linux 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. + +## Metalink + +Curl supports Metalink (both version 3 and 4 (RFC 5854) are supported), a way +to list multiple URIs and hashes for a file. Curl will 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. + +## 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 +https://curl.haxx.se/mail/. + +Please direct curl questions, feature requests and trouble reports to one of +these mailing lists instead of mailing any individual. + +Available lists include: + +### 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. + |