curl/docs/curl_easy_setopt.3

.\" You can view this file with:
.\" nroff -man [file]
.\" $Id$
.\"
.TH curl_easy_setopt 3 "30 Nov 2001" "libcurl 7.9.2" "libcurl Manual"
.SH NAME
curl_easy_setopt - Set curl easy-session options
.SH SYNOPSIS
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLoption option, parameter);
.ad
.SH DESCRIPTION
curl_easy_setopt() is used to tell libcurl how to behave. Most operations in
libcurl have default actions, and by using the appropriate options to
\fIcurl_easy_setopt\fP, you can change them.  All options are set with the
\fIoption\fP followed by a \fIparameter\fP. That parameter can be a long, a
function pointer or an object pointer, all depending on what the specific
option expects. Read this manual carefully as bad input values may cause
libcurl to behave badly!  You can only set one option in each function call. A
typical application uses many curl_easy_setopt() calls in the setup phase.

\fBNOTE:\fP strings passed to libcurl as 'char *' arguments, will not be
copied by the library. Instead you should keep them available until libcurl no
longer needs them. Failing to do so will cause very odd behavior or even
crashes.

\fBNOTE2:\fP options set with this function call are valid for the forthcoming
data transfers that are performed when you invoke \fIcurl_easy_perform\fP.
The options are not in any way reset between transfers, so if you want
subsequent transfers with different options, you must change them between the
transfers.

The \fIhandle\fP is the return code from a \fIcurl_easy_init(3)\fP or
\fIcurl_easy_duphandle(3)\fP call.
.SH OPTIONS
The options are listed in a sort of random order, but you'll figure it out!
.TP 0.8i
.B CURLOPT_FILE
Data pointer to pass to the file write function. Note that if you specify the
\fICURLOPT_WRITEFUNCTION\fP, this is the pointer you'll get as input. If you
don't use a callback, you must pass a 'FILE *' as libcurl will pass this to
fwrite() when writing data.

\fBNOTE:\fP If you're using libcurl as a win32 DLL, you MUST use the
\fICURLOPT_WRITEFUNCTION\fP if you set this option or you will experience
crashes.
.TP
.B CURLOPT_WRITEFUNCTION
Function pointer that should match the following prototype: \fBsize_t
function( void *ptr, size_t size, size_t nmemb, void *stream);\fP This
function gets called by libcurl as soon as there is data available to pass
available that needs to be saved. The size of the data pointed to by \fIptr\fP
is \fIsize\fP multiplied with \fInmemb\fP.  Return the number of bytes
actually taken care of. If that amount differs from the amount passed to your
function, it'll signal an error to the library and it will abort the transfer
and return \fICURLE_WRITE_ERROR\fP.

Set the \fIstream\fP argument with the \fBCURLOPT_FILE\fP option.

\fBNOTE:\fP you will be passed as much data as possible in all invokes, but
you cannot possibly make any assumptions. It may be one byte, it may be
thousands.
.TP
.B CURLOPT_INFILE
Data pointer to pass to the file read function. Note that if you specify the
\fICURLOPT_READFUNCTION\fP, this is the pointer you'll get as input. If you
don't specify a read callback, this must be a valid FILE *.

\fBNOTE:\fP If you're using libcurl as a win32 DLL, you MUST use a
\fICURLOPT_READFUNCTION\fP if you set this option.
.TP
.B CURLOPT_READFUNCTION
Function pointer that should match the following prototype: \fBsize_t
function( void *ptr, size_t size, size_t nmemb, void *stream);\fP This
function gets called by libcurl as soon as it needs to read data in order to
send it to the peer. The data area pointed at by the pointer \fIptr\fP may be
filled with at most \fIsize\fP multiplied with \fInmemb\fP number of
bytes. Your function must return the actual number of bytes that you stored in
that memory area. Returning -1 will signal an error to the library and cause
it to abort the current transfer immediately (with a \fICURLE_READ_ERROR\fP
return code).
.TP
.B CURLOPT_INFILESIZE
When uploading a file to a remote site, this option should be used to tell
libcurl what the expected size of the infile is.
.TP
.B CURLOPT_URL
The actual URL to deal with. The parameter should be a char * to a zero
terminated string. The string must remain present until curl no longer needs
it, as it doesn't copy the string.

\fBNOTE:\fP this option is (the only one) required to be set before
\fIcurl_easy_perform(3)\fP is called.
.TP
.B CURLOPT_PROXY
Set HTTP proxy to use. The parameter should be a char * to a zero terminated
string holding the host name or dotted IP address. To specify port number in
this string, append :[port] to the end of the host name. The proxy string may
be prefixed with [protocol]:// since any such prefix will be ignored. The
proxy's port number may optionally be specified with the separate option
\fICURLOPT_PROXYPORT\fP.

\fBNOTE:\fP when you tell the library to use a HTTP proxy, libcurl will
transparently convert operations to HTTP even if you specify a FTP URL
etc. This may have an impact on what other features of the library you can
use, such as CURLOPT_QUOTE and similar FTP specifics that don't work unless
you tunnel through the HTTP proxy. Such tunneling is activated with
\fICURLOPT_HTTPPROXYTUNNEL\fP.

\fBNOTE2:\fP libcurl respects the environment variables \fBhttp_proxy\fP,
\fBftp_proxy\fP, \fBall_proxy\fP etc, if any of those is set.
.TP
.B CURLOPT_PROXYPORT
Pass a long with this option to set the proxy port to connect to unless it is
specified in the proxy string \fICURLOPT_PROXY\fP.
.TP
.B CURLOPT_HTTPPROXYTUNNEL
Set the parameter to non-zero to get the library to tunnel all operations
through a given HTTP proxy. Note that there is a big difference between using
a proxy and to tunnel through it. If you don't know what this means, you
probably don't want this tunneling option. (Added in libcurl 7.3)
.TP
.B CURLOPT_VERBOSE
Set the parameter to non-zero to get the library to display a lot of verbose
information about its operations. Very useful for libcurl and/or protocol
debugging and understanding.

You hardly ever want this set in production use, you will almost always want
this when you debug/report problems.
.TP
.B CURLOPT_HEADER
A non-zero parameter tells the library to include the header in the body
output. This is only relevant for protocols that actually have headers
preceding the data (like HTTP).
.TP
.B CURLOPT_NOPROGRESS
A non-zero parameter tells the library to shut of the built-in progress meter
completely.

\fBNOTE:\fP future versions of libcurl is likely to not have any built-in
progress meter at all.
.TP
.B CURLOPT_NOBODY
A non-zero parameter tells the library to not include the body-part in the
output. This is only relevant for protocols that have separate header and body
parts.
.TP
.B CURLOPT_FAILONERROR
A non-zero parameter tells the library to fail silently if the HTTP code
returned is equal to or larger than 300. The default action would be to return
the page normally, ignoring that code.
.TP
.B CURLOPT_UPLOAD
A non-zero parameter tells the library to prepare for an upload. The
CURLOPT_INFILE and CURLOPT_INFILESIZE are also interesting for uploads.
.TP
.B CURLOPT_POST
A non-zero parameter tells the library to do a regular HTTP post. This is a
normal application/x-www-form-urlencoded kind, which is the most commonly used
one by HTML forms. See the CURLOPT_POSTFIELDS option for how to specify the
data to post and CURLOPT_POSTFIELDSIZE in how to set the data size. Starting
with libcurl 7.8, this option is obsolete. Using the CURLOPT_POSTFIELDS option
will imply this option.
.TP
.B CURLOPT_FTPLISTONLY
A non-zero parameter tells the library to just list the names of an ftp
directory, instead of doing a full directory listing that would include file
sizes, dates etc.
.TP
.B CURLOPT_FTPAPPEND
A non-zero parameter tells the library to append to the remote file instead of
overwrite it. This is only useful when uploading to a ftp site.
.TP
.B CURLOPT_NETRC
A non-zero parameter tells the library to scan your \fI~/.netrc\fP file to
find user name and password for the remote site you are about to access. Only
machine name, user name and password is taken into account (init macros and
similar things aren't supported).

\fBNote:\fP libcurl does not verify that the file has the correct properties
set (as the standard Unix ftp client does). It should only be readable by
user.
.TP
.B CURLOPT_FOLLOWLOCATION
A non-zero parameter tells the library to follow any Location: header that the
server sends as part of a HTTP header.

\fBNOTE:\fP this means that the library will re-send the same request on the
new location and follow new Location: headers all the way until no more such
headers are returned. \fICURLOPT_MAXREDIRS\fP can be used to limit the number
of redirects libcurl will follow.
.TP
.B CURLOPT_TRANSFERTEXT
A non-zero parameter tells the library to use ASCII mode for ftp transfers,
instead of the default binary transfer. For LDAP transfers it gets the data in
plain text instead of HTML and for win32 systems it does not set the stdout to
binary mode. This option can be usable when transferring text data between
systems with different views on certain characters, such as newlines or
similar.
.TP
.B CURLOPT_PUT
A non-zero parameter tells the library to use HTTP PUT to transfer data. The
data should be set with CURLOPT_INFILE and CURLOPT_INFILESIZE.
.TP
.B CURLOPT_USERPWD
Pass a char * as parameter, which should be [user name]:[password] to use for
the connection. If the password is left out, you will be prompted for it.
\fICURLOPT_PASSWDFUNCTION\fP can be used to set your own prompt function.
.TP
.B CURLOPT_PROXYUSERPWD
Pass a char * as parameter, which should be [user name]:[password] to use for
the connection to the HTTP proxy. If the password is left out, you will be
prompted for it. \fICURLOPT_PASSWDFUNCTION\fP can be used to set your own
prompt function.
.TP
.B CURLOPT_RANGE
Pass a char * as parameter, which should contain the specified range you
want. It should be in the format "X-Y", where X or Y may be left out. HTTP
transfers also support several intervals, separated with commas as in
\fI"X-Y,N-M"\fP. Using this kind of multiple intervals will cause the HTTP
server to send the response document in pieces (using standard MIME separation
techniques).
.TP
.B CURLOPT_ERRORBUFFER
Pass a char * to a buffer that the libcurl may store human readable error
messages in. This may be more helpful than just the return code from the
library. The buffer must be at least CURL_ERROR_SIZE big.

\fBNote:\fP if the library does not return an error, the buffer may not have
been touched. Do not rely on the contents in those cases.
.TP
.B CURLOPT_TIMEOUT
Pass a long as parameter containing the maximum time in seconds that you allow
the libcurl transfer operation to take. Normally, name lookups can take a
considerable time and limiting operations to less than a few minutes risk
aborting perfectly normal operations. This option will cause curl to use the
SIGALRM to enable time-outing system calls.

\fBNOTE:\fP this does not work in Unix multi-threaded programs, as it uses
signals.
.TP
.B CURLOPT_POSTFIELDS
Pass a char * as parameter, which should be the full data to post in a HTTP
post operation. This is a normal application/x-www-form-urlencoded kind, which
is the most commonly used one by HTML forms. See also the CURLOPT_POST. Since
7.8, using CURLOPT_POSTFIELDS implies CURLOPT_POST.

\fBNote:\fP to make multipart/formdata posts (aka rfc1867-posts), check out
the \fICURLOPT_HTTPPOST\fP option.
.TP
.B CURLOPT_POSTFIELDSIZE
If you want to post data to the server without letting libcurl do a strlen()
to measure the data size, this option must be used. When this option is used
you can post fully binary data, which otherwise is likely to fail. If this
size is set to zero, the library will use strlen() to get the size. (Added in
libcurl 7.2)
.TP
.B CURLOPT_REFERER
Pass a pointer to a zero terminated string as parameter. It will be used to
set the Referer: header in the http request sent to the remote server. This
can be used to fool servers or scripts. You can also set any custom header
with \fICURLOPT_HTTPHEADER\fP.
.TP
.B CURLOPT_USERAGENT
Pass a pointer to a zero terminated string as parameter. It will be used to
set the User-Agent: header in the http request sent to the remote server. This
can be used to fool servers or scripts. You can also set any custom header
with \fICURLOPT_HTTPHEADER\fP.
.TP
.B CURLOPT_FTPPORT
Pass a pointer to a zero terminated string as parameter. It will be used to
get the IP address to use for the ftp PORT instruction. The PORT instruction
tells the remote server to connect to our specified IP address. The string may
be a plain IP address, a host name, an network interface name (under Unix) or
just a '-' letter to let the library use your systems default IP
address. Default FTP operations are passive, and thus won't use PORT.
.TP
.B CURLOPT_LOW_SPEED_LIMIT
Pass a long as parameter. It contains the transfer speed in bytes per second
that the transfer should be below during CURLOPT_LOW_SPEED_TIME seconds for
the library to consider it too slow and abort.
.TP
.B CURLOPT_LOW_SPEED_TIME
Pass a long as parameter. It contains the time in seconds that the transfer
should be below the CURLOPT_LOW_SPEED_LIMIT for the library to consider it too
slow and abort.
.TP
.B CURLOPT_RESUME_FROM
Pass a long as parameter. It contains the offset in number of bytes that you
want the transfer to start from.
.TP
.B CURLOPT_COOKIE
Pass a pointer to a zero terminated string as parameter. It will be used to
set a cookie in the http request. The format of the string should be
[NAME]=[CONTENTS]; Where NAME is the cookie name.
.TP
.B CURLOPT_HTTPHEADER
Pass a pointer to a linked list of HTTP headers to pass to the server in your
HTTP request. The linked list should be a fully valid list of \fBstruct
curl_slist\fP structs properly filled in. Use \fIcurl_slist_append(3)\fP to
create the list and \fIcurl_slist_free_all(3)\fP to clean up an entire
list. If you add a header that is otherwise generated and used by libcurl
internally, your added one will be used instead. If you add a header with no
contents as in 'Accept:' (no data on the right side of the colon), the
internally used header will get disabled. Thus, using this option you can add
new headers, replace internal headers and remove internal headers.

\fBNOTE:\fPThe most commonly replaced headers have "shortcuts" in the options
CURLOPT_COOKIE, CURLOPT_USERAGENT and CURLOPT_REFERER.
.TP
.B CURLOPT_HTTPPOST
Tells libcurl you want a multipart/formdata HTTP POST to be made and you
instruct what data to pass on to the server.  Pass a pointer to a linked list
of HTTP post structs as parameter.  The linked list should be a fully valid
list of 'struct HttpPost' structs properly filled in. The best and most
elegant way to do this, is to use \fIcurl_formadd(3)\fP as documented. The
data in this list must remained intact until you close this curl handle again
with \fIcurl_easy_cleanup(3)\fP.
.TP
.B CURLOPT_SSLCERT
Pass a pointer to a zero terminated string as parameter. The string should be
the file name of your certificate in PEM format.
.TP
.B CURLOPT_SSLCERTPASSWD
Pass a pointer to a zero terminated string as parameter. It will be used as
the password required to use the CURLOPT_SSLCERT certificate. If the password
is not supplied, you will be prompted for it. \fICURLOPT_PASSWDFUNCTION\fP can
be used to set your own prompt function.
.TP
.B CURLOPT_CRLF
Convert Unix newlines to CRLF newlines on FTP uploads.
.TP
.B CURLOPT_QUOTE
Pass a pointer to a linked list of FTP commands to pass to the server prior to
your ftp request. The linked list should be a fully valid list of 'struct
curl_slist' structs properly filled in. Use \fIcurl_slist_append(3)\fP to
append strings (commands) to the list, and clear the entire list afterwards
with \fIcurl_slist_free_all(3)\fP. Disable this operation again by setting a
NULL to this option.
.TP
.B CURLOPT_POSTQUOTE
Pass a pointer to a linked list of FTP commands to pass to the server after
your ftp transfer request. The linked list should be a fully valid list of
struct curl_slist structs properly filled in as described for
\fICURLOPT_QUOTE\fP. Disable this operation again by setting a NULL to this
option.
.TP
.B CURLOPT_WRITEHEADER
Pass a pointer to be used to write the header part of the received data to. If
you don't use your own callback to take care of the writing, this must be a
valid FILE *. See also the \fICURLOPT_HEADERFUNCTION\fP option below on how to set a
custom get-all-headers callback.
.TP
.B CURLOPT_HEADERFUNCTION
Function pointer that should match the following prototype: \fIsize_t
function( void *ptr, size_t size, size_t nmemb, void *stream);\fP. This
function gets called by libcurl as soon as there is received header data that
needs to be written down. The headers are guaranteed to be written one-by-one
and only complete lines are written. Parsing headers should be easy enough
using this. The size of the data pointed to by \fIptr\fP is \fIsize\fP
multiplied with \fInmemb\fP.  The pointer named \fIstream\fP will be the one
you passed to libcurl with the \fICURLOPT_WRITEHEADER\fP option.  Return the
number of bytes actually written or return -1 to signal error to the library
(it will cause it to abort the transfer with a \fICURLE_WRITE_ERROR\fP return
code). (Added in libcurl 7.7.2)
.TP
.B CURLOPT_COOKIEFILE
Pass a pointer to a zero terminated string as parameter. It should contain the
name of your file holding cookie data. The cookie data may be in Netscape /
Mozilla cookie data format or just regular HTTP-style headers dumped to a
file.
.TP
.B CURLOPT_SSLVERSION
Pass a long as parameter. Set what version of SSL to attempt to use, 2 or
3. By default, the SSL library will try to solve this by itself although some
servers make this difficult why you at times may have to use this option.
.TP
.B CURLOPT_TIMECONDITION
Pass a long as parameter. This defines how the CURLOPT_TIMEVALUE time value is
treated. You can set this parameter to TIMECOND_IFMODSINCE or
TIMECOND_IFUNMODSINCE. This is a HTTP-only feature. (TBD)
.TP
.B CURLOPT_TIMEVALUE
Pass a long as parameter. This should be the time in seconds since 1 jan 1970,
and the time will be used as specified in CURLOPT_TIMECONDITION or if that
isn't used, it will be TIMECOND_IFMODSINCE by default.
.TP
.B CURLOPT_CUSTOMREQUEST
Pass a pointer to a zero terminated string as parameter. It will be user
instead of GET or HEAD when doing the HTTP request. This is useful for doing
DELETE or other more or less obscure HTTP requests. Don't do this at will,
make sure your server supports the command first.
.TP
.B CURLOPT_STDERR
Pass a FILE * as parameter. This is the stream to use instead of stderr
internally when reporting errors.
.TP
.B CURLOPT_INTERFACE
Pass a char * as parameter. This set the interface name to use as outgoing
network interface. The name can be an interface name, an IP address or a host
name. (Added in libcurl 7.3)
.TP
.B CURLOPT_KRB4LEVEL
Pass a char * as parameter. Set the krb4 security level, this also enables
krb4 awareness.  This is a string, 'clear', 'safe', 'confidential' or
\&'private'.  If the string is set but doesn't match one of these, 'private'
will be used. Set the string to NULL to disable kerberos4. The kerberos
support only works for FTP. (Added in libcurl 7.3)
.TP
.B CURLOPT_PROGRESSFUNCTION
Function pointer that should match the \fIcurl_progress_callback\fP prototype
found in \fI<curl/curl.h>\fP. This function gets called by libcurl instead of
its internal equivalent with a frequent interval during data transfer.
Unknown/unused argument values will be set to zero (like if you only download
data, the upload size will remain 0). Returning a non-zero value from this
callback will cause libcurl to abort the transfer and return
\fICURLE_ABORTED_BY_CALLBACK\fP.
.TP
.B CURLOPT_PROGRESSDATA
Pass a pointer that will be untouched by libcurl and passed as the first
argument in the progress callback set with \fICURLOPT_PROGRESSFUNCTION\fP.
.TP
.B CURLOPT_SSL_VERIFYPEER
Pass a long that is set to a non-zero value to make curl verify the peer's
certificate. The certificate to verify against must be specified with the
CURLOPT_CAINFO option. (Added in 7.4.2)
.TP
.B CURLOPT_CAINFO
Pass a char * to a zero terminated file naming holding the certificate to
verify the peer with. This only makes sense when used in combination with the
CURLOPT_SSL_VERIFYPEER option. (Added in 7.4.2)
.TP
.B CURLOPT_PASSWDFUNCTION
Pass a pointer to a \fIcurl_passwd_callback\fP function that will be called
instead of the internal one if libcurl requests a password. The function must
match this prototype: \fBint my_getpass(void *client, char *prompt, char*
buffer, int buflen );\fP.  If set to NULL, it equals to making the function
always fail. If the function returns a non-zero value, it will abort the
operation and an error (CURLE_BAD_PASSWORD_ENTERED) will be returned.
\fIclient\fP is a generic pointer, see \fICURLOPT_PASSWDDATA\fP.  \fIprompt\fP
is a zero-terminated string that is text that prefixes the input request.
\fIbuffer\fP is a pointer to data where the entered password should be stored
and \fIbuflen\fP is the maximum number of bytes that may be written in the
buffer.  (Added in 7.4.2)
.TP
.B CURLOPT_PASSWDDATA
Pass a void * to whatever data you want. The passed pointer will be the first
argument sent to the specifed \fICURLOPT_PASSWDFUNCTION\fP function. (Added in
7.4.2)
.TP
.B CURLOPT_FILETIME
Pass a long. If it is a non-zero value, libcurl will attempt to get the
modification date of the remote document in this operation. This requires that
the remote server sends the time or replies to a time querying command. The
\fIcurl_easy_getinfo(3)\fP function with the \fICURLINFO_FILETIME\fP argument
can be used after a transfer to extract the received time (if any). (Added in
7.5)
.TP
.B CURLOPT_MAXREDIRS
Pass a long. The set number will be the redirection limit. If that many
redirections have been followed, the next redirect will cause an error
(\fICURLE_TOO_MANY_REDIRECTS\fP). This option only makes sense if the
\fICURLOPT_FOLLOWLOCATION\fP is used at the same time. (Added in 7.5)
.TP
.B CURLOPT_MAXCONNECTS
Pass a long. The set number will be the persistant connection cache size. The
set amount will be the maximum amount of simultaneous connections that libcurl
may cache between file transfers. Default is 5, and there isn't much point in
changing this value unless you are perfectly aware of how this work and
changes libcurl's behaviour.

\fBNOTE:\fP if you already have performed transfers with this curl handle,
setting a smaller MAXCONNECTS than before may cause open connections to get
closed unnecessarily. (Added in 7.7)
.TP
.B CURLOPT_CLOSEPOLICY
Pass a long. This option sets what policy libcurl should use when the
connection cache is filled and one of the open connections has to be closed to
make room for a new connection. This must be one of the CURLCLOSEPOLICY_*
defines. Use \fICURLCLOSEPOLICY_LEAST_RECENTLY_USED\fP to make libcurl close
the connection that was least recently used, that connection is also least
likely to be capable of re-use. Use \fICURLCLOSEPOLICY_OLDEST\fP to make
libcurl close the oldest connection, the one that was created first among the
ones in the connection cache. The other close policies are not support
yet. (Added in 7.7)
.TP
.B CURLOPT_FRESH_CONNECT
Pass a long. Set to non-zero to make the next transfer use a new (fresh)
connection by force. If the connection cache is full before this connection,
one of the existing connections will be closed as according to the selected or
default policy. This option should be used with caution and only if you
understand what it does. Set this to 0 to have libcurl attempt re-using an
existing connection (default behavior).  (Added in 7.7)
.TP
.B CURLOPT_FORBID_REUSE
Pass a long. Set to non-zero to make the next transfer explicitly close the
connection when done. Normally, libcurl keep all connections alive when done
with one transfer in case there comes a succeeding one that can re-use them.
This option should be used with caution and only if you understand what it
does. Set to 0 to have libcurl keep the connection open for possibly later
re-use (default behavior). (Added in 7.7)
.TP
.B CURLOPT_RANDOM_FILE
Pass a char * to a zero terminated file name. The file will be used to read
from to seed the random engine for SSL. The more random the specified file is,
the more secure will the SSL connection become.
.TP
.B CURLOPT_EGDSOCKET
Pass a char * to the zero terminated path name to the Entropy Gathering Daemon
socket. It will be used to seed the random engine for SSL.
.TP
.B CURLOPT_CONNECTTIMEOUT
Pass a long. It should contain the maximum time in seconds that you allow the
connection to the server to take.  This only limits the connection phase, once
it has connected, this option is of no more use. Set to zero to disable
connection timeout (it will then only timeout on the system's internal
timeouts). See also the \fICURLOPT_TIMEOUT\fP option.

\fBNOTE:\fP this does not work in unix multi-threaded programs, as it uses
signals.
.TP
.B CURLOPT_HTTPGET
Pass a long. If the long is non-zero, this forces the HTTP request to get back
to GET. Only really usable if POST, PUT or a custom request have been used
previously using the same curl handle. (Added in 7.8.1)
.TP
.B CURLOPT_SSL_VERIFYHOST
Pass a long. Set if we should verify the Common name from the peer certificate
in the SSL handshake, set 1 to check existence, 2 to ensure that it matches
the provided hostname. (Added in 7.8.1)
.TP
.B CURLOPT_COOKIEJAR
Pass a file name as char *, zero terminated. This will make libcurl dump all
internally known cookies to the specified file when \fIcurl_easy_cleanup(3)\fP
is called. If no cookies are known, no file will be created. Specify "-" to
instead have the cookies written to stdout.
.TP
.B CURLOPT_SSL_CIPHER_LIST
Pass a char *, pointing to a zero terminated string holding the list of
ciphers to use for the SSL connection. The list must be syntactly correct, it
consists of one or more cipher strings separated by colons. Commas or spaces
are also acceptable separators but colons are normally used, \!, \- and \+ can
be used as operators. Valid examples of cipher lists include 'RC4-SHA',
\'SHA1+DES\', 'TLSv1' and 'DEFAULT'. The default list is normally set when you
compile OpenSSL.

You'll find more details about cipher lists on this URL:
\fIhttp://www.openssl.org/docs/apps/ciphers.html\fP
.TP
.B CURLOPT_HTTP_VERSION
Pass a long, set to one of the values described below. They force libcurl to
use the specific HTTP versions. This is not sensible to do unless you have a
good reason.
.RS
.TP 5
.B CURL_HTTP_VERSION_NONE
We don't care about what version the library uses. libcurl will use whatever
it thinks fit.
.TP
.B CURL_HTTP_VERSION_1_0
Enforce HTTP 1.0 requests.
.TP
.B CURL_HTTP_VERSION_1_1
Enforce HTTP 1.1 requests.
.RE
.TP
.B CURLOPT_FTP_USE_EPSV
Pass a long. If the value is non-zero, it tells curl to use the EPSV command
when doing passive FTP downloads (which is always does by default). Using EPSV
means that it will first attempt to use EPSV before using PASV, but if you
pass FALSE (zero) to this option, it will not try using EPSV, only plain PASV.
.PP
.SH RETURN VALUE
CURLE_OK (zero) means that the option was set properly, non-zero means an
error occurred as \fI<curl/curl.h>\fP defines.
.SH "SEE ALSO"
.BR curl_easy_init "(3), " curl_easy_cleanup "(3), "
.SH BUGS
If you find any bugs, or just have questions, subscribe to one of the mailing
lists and post. We won't bite.