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Set an option for a cURL transfer
cURL Functions
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curl_setopt

(PHP 4 >= 4.0.2, PHP 5)

curl_setoptSet an option for a cURL transfer

Description

bool curl_setopt ( resource $ch , int $option , mixed $value )

Sets an option on the given cURL session handle.

Parameters

ch

A cURL handle returned by curl_init().

option

The CURLOPT_XXX option to set.

value

The value to be set on option.

value should be a bool for the following values of the option parameter:
Option Set value to Notes
CURLOPT_AUTOREFERER TRUE to automatically set the Referer: field in requests where it follows a Location: redirect.
CURLOPT_BINARYTRANSFER TRUE to return the raw output when CURLOPT_RETURNTRANSFER is used. From PHP 5.1.3, this option has no effect: the raw output will always be returned when CURLOPT_RETURNTRANSFER is used.
CURLOPT_COOKIESESSION TRUE to mark this as a new cookie "session". It will force libcurl to ignore all cookies it is about to load that are "session cookies" from the previous session. By default, libcurl always stores and loads all cookies, independent if they are session cookies or not. Session cookies are cookies without expiry date and they are meant to be alive and existing for this "session" only.
CURLOPT_CERTINFO TRUE to output SSL certification information to STDERR on secure transfers. Added in cURL 7.19.1. Available since PHP 5.3.2. Requires CURLOPT_VERBOSE to be on to have an effect.
CURLOPT_CONNECT_ONLY TRUE tells the library to perform all the required proxy authentication and connection setup, but no data transfer. This option is implemented for HTTP, SMTP and POP3. Added in 7.15.2. Available since PHP 5.5.0.
CURLOPT_CRLF TRUE to convert Unix newlines to CRLF newlines on transfers.
CURLOPT_DNS_USE_GLOBAL_CACHE TRUE to use a global DNS cache. This option is not thread-safe and is enabled by default.
CURLOPT_FAILONERROR TRUE to fail verbosely if the HTTP code returned is greater than or equal to 400. The default behavior is to return the page normally, ignoring the code.
CURLOPT_FILETIME TRUE to attempt to retrieve the modification date of the remote document. This value can be retrieved using the CURLINFO_FILETIME option with curl_getinfo().
CURLOPT_FOLLOWLOCATION TRUE to follow any "Location: " header that the server sends as part of the HTTP header (note this is recursive, PHP will follow as many "Location: " headers that it is sent, unless CURLOPT_MAXREDIRS is set).
CURLOPT_FORBID_REUSE TRUE to force the connection to explicitly close when it has finished processing, and not be pooled for reuse.
CURLOPT_FRESH_CONNECT TRUE to force the use of a new connection instead of a cached one.
CURLOPT_FTP_USE_EPRT TRUE to use EPRT (and LPRT) when doing active FTP downloads. Use FALSE to disable EPRT and LPRT and use PORT only.
CURLOPT_FTP_USE_EPSV TRUE to first try an EPSV command for FTP transfers before reverting back to PASV. Set to FALSE to disable EPSV.
CURLOPT_FTP_CREATE_MISSING_DIRS TRUE to create missing directories when an FTP operation encounters a path that currently doesn't exist.
CURLOPT_FTPAPPEND TRUE to append to the remote file instead of overwriting it.
CURLOPT_FTPASCII An alias of CURLOPT_TRANSFERTEXT. Use that instead.
CURLOPT_FTPLISTONLY TRUE to only list the names of an FTP directory.
CURLOPT_HEADER TRUE to include the header in the output.
CURLINFO_HEADER_OUT TRUE to track the handle's request string. Available since PHP 5.1.3. The CURLINFO_ prefix is intentional.
CURLOPT_HTTPGET TRUE to reset the HTTP request method to GET. Since GET is the default, this is only necessary if the request method has been changed.
CURLOPT_HTTPPROXYTUNNEL TRUE to tunnel through a given HTTP proxy.
CURLOPT_MUTE TRUE to be completely silent with regards to the cURL functions. Removed in cURL 7.15.5 (You can use CURLOPT_RETURNTRANSFER instead)
CURLOPT_NETRC TRUE to scan the ~/.netrc file to find a username and password for the remote site that a connection is being established with.
CURLOPT_NOBODY TRUE to exclude the body from the output. Request method is then set to HEAD. Changing this to FALSE does not change it to GET.
CURLOPT_NOPROGRESS

TRUE to disable the progress meter for cURL transfers.

Note:

PHP automatically sets this option to TRUE, this should only be changed for debugging purposes.

CURLOPT_NOSIGNAL TRUE to ignore any cURL function that causes a signal to be sent to the PHP process. This is turned on by default in multi-threaded SAPIs so timeout options can still be used. Added in cURL 7.10.
CURLOPT_POST TRUE to do a regular HTTP POST. This POST is the normal application/x-www-form-urlencoded kind, most commonly used by HTML forms.
CURLOPT_PUT TRUE to HTTP PUT a file. The file to PUT must be set with CURLOPT_INFILE and CURLOPT_INFILESIZE.
CURLOPT_RETURNTRANSFER TRUE to return the transfer as a string of the return value of curl_exec() instead of outputting it out directly.
CURLOPT_SSL_VERIFYPEER FALSE to stop cURL from verifying the peer's certificate. Alternate certificates to verify against can be specified with the CURLOPT_CAINFO option or a certificate directory can be specified with the CURLOPT_CAPATH option. TRUE by default as of cURL 7.10. Default bundle installed as of cURL 7.10.
CURLOPT_TRANSFERTEXT TRUE to use ASCII mode for FTP transfers. For LDAP, it retrieves data in plain text instead of HTML. On Windows systems, it will not set STDOUT to binary mode.
CURLOPT_UNRESTRICTED_AUTH TRUE to keep sending the username and password when following locations (using CURLOPT_FOLLOWLOCATION), even when the hostname has changed.
CURLOPT_UPLOAD TRUE to prepare for an upload.
CURLOPT_VERBOSE TRUE to output verbose information. Writes output to STDERR, or the file specified using CURLOPT_STDERR.

value should be an integer for the following values of the option parameter:
Option Set value to Notes
CURLOPT_BUFFERSIZE The size of the buffer to use for each read. There is no guarantee this request will be fulfilled, however. Added in cURL 7.10.
CURLOPT_CLOSEPOLICY One of the CURLCLOSEPOLICY_* values.

Note:

This option is deprecated, as it was never implemented in cURL and never had any effect.

Removed in PHP 5.6.0.
CURLOPT_CONNECTTIMEOUT The number of seconds to wait while trying to connect. Use 0 to wait indefinitely.
CURLOPT_CONNECTTIMEOUT_MS The number of milliseconds to wait while trying to connect. Use 0 to wait indefinitely. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second. Added in cURL 7.16.2. Available since PHP 5.2.3.
CURLOPT_DNS_CACHE_TIMEOUT The number of seconds to keep DNS entries in memory. This option is set to 120 (2 minutes) by default.
CURLOPT_FTPSSLAUTH The FTP authentication method (when is activated): CURLFTPAUTH_SSL (try SSL first), CURLFTPAUTH_TLS (try TLS first), or CURLFTPAUTH_DEFAULT (let cURL decide). Added in cURL 7.12.2.
CURLOPT_HTTP_VERSION CURL_HTTP_VERSION_NONE (default, lets CURL decide which version to use), CURL_HTTP_VERSION_1_0 (forces HTTP/1.0), or CURL_HTTP_VERSION_1_1 (forces HTTP/1.1).
CURLOPT_HTTPAUTH

The HTTP authentication method(s) to use. The options are: CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_ANY, and CURLAUTH_ANYSAFE.

The bitwise | (or) operator can be used to combine more than one method. If this is done, cURL will poll the server to see what methods it supports and pick the best one.

CURLAUTH_ANY is an alias for CURLAUTH_BASIC | CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURLAUTH_NTLM.

CURLAUTH_ANYSAFE is an alias for CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURLAUTH_NTLM.

CURLOPT_INFILESIZE The expected size, in bytes, of the file when uploading a file to a remote site. Note that using this option will not stop libcurl from sending more data, as exactly what is sent depends on CURLOPT_READFUNCTION.
CURLOPT_LOW_SPEED_LIMIT The transfer speed, in bytes per second, that the transfer should be below during the count of CURLOPT_LOW_SPEED_TIME seconds before PHP considers the transfer too slow and aborts.
CURLOPT_LOW_SPEED_TIME The number of seconds the transfer speed should be below CURLOPT_LOW_SPEED_LIMIT before PHP considers the transfer too slow and aborts.
CURLOPT_MAXCONNECTS The maximum amount of persistent connections that are allowed. When the limit is reached, CURLOPT_CLOSEPOLICY is used to determine which connection to close.
CURLOPT_MAXREDIRS The maximum amount of HTTP redirections to follow. Use this option alongside CURLOPT_FOLLOWLOCATION.
CURLOPT_PORT An alternative port number to connect to.
CURLOPT_PROTOCOLS

Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in the transfer. This allows you to have a libcurl built to support a wide range of protocols but still limit specific transfers to only be allowed to use a subset of them. By default libcurl will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS.

Valid protocol options are: CURLPROTO_HTTP, CURLPROTO_HTTPS, CURLPROTO_FTP, CURLPROTO_FTPS, CURLPROTO_SCP, CURLPROTO_SFTP, CURLPROTO_TELNET, CURLPROTO_LDAP, CURLPROTO_LDAPS, CURLPROTO_DICT, CURLPROTO_FILE, CURLPROTO_TFTP, CURLPROTO_ALL

Added in cURL 7.19.4.
CURLOPT_PROXYAUTH The HTTP authentication method(s) to use for the proxy connection. Use the same bitmasks as described in CURLOPT_HTTPAUTH. For proxy authentication, only CURLAUTH_BASIC and CURLAUTH_NTLM are currently supported. Added in cURL 7.10.7.
CURLOPT_PROXYPORT The port number of the proxy to connect to. This port number can also be set in CURLOPT_PROXY.
CURLOPT_PROXYTYPE Either CURLPROXY_HTTP (default) or CURLPROXY_SOCKS5. Added in cURL 7.10.
CURLOPT_REDIR_PROTOCOLS Bitmask of CURLPROTO_* values. If used, this bitmask limits what protocols libcurl may use in a transfer that it follows to in a redirect when CURLOPT_FOLLOWLOCATION is enabled. This allows you to limit specific transfers to only be allowed to use a subset of protocols in redirections. By default libcurl will allow all protocols except for FILE and SCP. This is a difference compared to pre-7.19.4 versions which unconditionally would follow to all protocols supported. See also CURLOPT_PROTOCOLS for protocol constant values. Added in cURL 7.19.4.
CURLOPT_RESUME_FROM The offset, in bytes, to resume a transfer from.
CURLOPT_SSL_VERIFYHOST 1 to check the existence of a common name in the SSL peer certificate. 2 to check the existence of a common name and also verify that it matches the hostname provided. In production environments the value of this option should be kept at 2 (default value). Support for value 1 removed in cURL 7.28.1
CURLOPT_SSLVERSION The SSL version (2 or 3) to use. By default PHP will try to determine this itself, although in some cases this must be set manually.
CURLOPT_TIMECONDITION How CURLOPT_TIMEVALUE is treated. Use CURL_TIMECOND_IFMODSINCE to return the page only if it has been modified since the time specified in CURLOPT_TIMEVALUE. If it hasn't been modified, a "304 Not Modified" header will be returned assuming CURLOPT_HEADER is TRUE. Use CURL_TIMECOND_IFUNMODSINCE for the reverse effect. CURL_TIMECOND_IFMODSINCE is the default.
CURLOPT_TIMEOUT The maximum number of seconds to allow cURL functions to execute.
CURLOPT_TIMEOUT_MS The maximum number of milliseconds to allow cURL functions to execute. If libcurl is built to use the standard system name resolver, that portion of the connect will still use full-second resolution for timeouts with a minimum timeout allowed of one second. Added in cURL 7.16.2. Available since PHP 5.2.3.
CURLOPT_TIMEVALUE The time in seconds since January 1st, 1970. The time will be used by CURLOPT_TIMECONDITION. By default, CURL_TIMECOND_IFMODSINCE is used.
CURLOPT_MAX_RECV_SPEED_LARGE If a download exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed. Added in cURL 7.15.5. Available since PHP 5.4.0.
CURLOPT_MAX_SEND_SPEED_LARGE If an upload exceeds this speed (counted in bytes per second) on cumulative average during the transfer, the transfer will pause to keep the average rate less than or equal to the parameter value. Defaults to unlimited speed. Added in cURL 7.15.5. Available since PHP 5.4.0.
CURLOPT_SSH_AUTH_TYPES A bitmask consisting of one or more of CURLSSH_AUTH_PUBLICKEY, CURLSSH_AUTH_PASSWORD, CURLSSH_AUTH_HOST, CURLSSH_AUTH_KEYBOARD. Set to CURLSSH_AUTH_ANY to let libcurl pick one. Added in cURL 7.16.1.
CURLOPT_IPRESOLVE Allows an application to select what kind of IP addresses to use when resolving host names. This is only interesting when using host names that resolve addresses using more than one version of IP, possible values are CURL_IPRESOLVE_WHATEVER, CURL_IPRESOLVE_V4, CURL_IPRESOLVE_V6, by default CURL_IPRESOLVE_WHATEVER. Added in cURL 7.10.8.

value should be a string for the following values of the option parameter:
Option Set value to Notes
CURLOPT_CAINFO The name of a file holding one or more certificates to verify the peer with. This only makes sense when used in combination with CURLOPT_SSL_VERIFYPEER. Requires absolute path.
CURLOPT_CAPATH A directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER.
CURLOPT_COOKIE The contents of the "Cookie: " header to be used in the HTTP request. Note that multiple cookies are separated with a semicolon followed by a space (e.g., "fruit=apple; colour=red")
CURLOPT_COOKIEFILE The name of the file containing the cookie data. The cookie file can be in Netscape format, or just plain HTTP-style headers dumped into a file. If the name is an empty string, no cookies are loaded, but cookie handling is still enabled.
CURLOPT_COOKIEJAR The name of a file to save all internal cookies to when the handle is closed, e.g. after a call to curl_close.
CURLOPT_CUSTOMREQUEST

A custom request method to use instead of "GET" or "HEAD" when doing a HTTP request. This is useful for doing "DELETE" or other, more obscure HTTP requests. Valid values are things like "GET", "POST", "CONNECT" and so on; i.e. Do not enter a whole HTTP request line here. For instance, entering "GET /index HTTP/1.0\r\n\r\n" would be incorrect.

Note:

Don't do this without making sure the server supports the custom request method first.

CURLOPT_EGDSOCKET Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket.
CURLOPT_ENCODING The contents of the "Accept-Encoding: " header. This enables decoding of the response. Supported encodings are "identity", "deflate", and "gzip". If an empty string, "", is set, a header containing all supported encoding types is sent. Added in cURL 7.10.
CURLOPT_FTPPORT The value which 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 hostname, a network interface name (under Unix), or just a plain '-' to use the systems default IP address.
CURLOPT_INTERFACE The name of the outgoing network interface to use. This can be an interface name, an IP address or a host name.
CURLOPT_KEYPASSWD The password required to use the CURLOPT_SSLKEY or CURLOPT_SSH_PRIVATE_KEYFILE private key. Added in cURL 7.16.1.
CURLOPT_KRB4LEVEL The KRB4 (Kerberos 4) security level. Any of the following values (in order from least to most powerful) are valid: "clear", "safe", "confidential", "private".. If the string does not match one of these, "private" is used. Setting this option to NULL will disable KRB4 security. Currently KRB4 security only works with FTP transactions.
CURLOPT_POSTFIELDS The full data to post in a HTTP "POST" operation. To post a file, prepend a filename with @ and use the full path. The filetype can be explicitly specified by following the filename with the type in the format ';type=mimetype'. This parameter can either be passed as a urlencoded string like 'para1=val1&para2=val2&...' or as an array with the field name as key and field data as value. If value is an array, the Content-Type header will be set to multipart/form-data. As of PHP 5.2.0, value must be an array if files are passed to this option with the @ prefix. As of PHP 5.5.0, the @ prefix is deprecated and files can be sent using CURLFile.
CURLOPT_PROXY The HTTP proxy to tunnel requests through.
CURLOPT_PROXYUSERPWD A username and password formatted as "[username]:[password]" to use for the connection to the proxy.
CURLOPT_RANDOM_FILE A filename to be used to seed the random number generator for SSL.
CURLOPT_RANGE Range(s) of data to retrieve in the format "X-Y" where X or Y are optional. HTTP transfers also support several intervals, separated with commas in the format "X-Y,N-M".
CURLOPT_REFERER The contents of the "Referer: " header to be used in a HTTP request.
CURLOPT_SSH_HOST_PUBLIC_KEY_MD5 A string containing 32 hexadecimal digits. The string should be the MD5 checksum of the remote host's public key, and libcurl will reject the connection to the host unless the md5sums match. This option is only for SCP and SFTP transfers. Added in cURL 7.17.1.
CURLOPT_SSH_PUBLIC_KEYFILE The file name for your public key. If not used, libcurl defaults to $HOME/.ssh/id_dsa.pub if the HOME environment variable is set, and just "id_dsa.pub" in the current directory if HOME is not set. Added in cURL 7.16.1.
CURLOPT_SSH_PRIVATE_KEYFILE The file name for your private key. If not used, libcurl defaults to $HOME/.ssh/id_dsa if the HOME environment variable is set, and just "id_dsa" in the current directory if HOME is not set. If the file is password-protected, set the password with CURLOPT_KEYPASSWD. Added in cURL 7.16.1.
CURLOPT_SSL_CIPHER_LIST A list of ciphers to use for SSL. For example, RC4-SHA and TLSv1 are valid cipher lists.
CURLOPT_SSLCERT The name of a file containing a PEM formatted certificate.
CURLOPT_SSLCERTPASSWD The password required to use the CURLOPT_SSLCERT certificate.
CURLOPT_SSLCERTTYPE The format of the certificate. Supported formats are "PEM" (default), "DER", and "ENG". Added in cURL 7.9.3.
CURLOPT_SSLENGINE The identifier for the crypto engine of the private SSL key specified in CURLOPT_SSLKEY.
CURLOPT_SSLENGINE_DEFAULT The identifier for the crypto engine used for asymmetric crypto operations.
CURLOPT_SSLKEY The name of a file containing a private SSL key.
CURLOPT_SSLKEYPASSWD

The secret password needed to use the private SSL key specified in CURLOPT_SSLKEY.

Note:

Since this option contains a sensitive password, remember to keep the PHP script it is contained within safe.

CURLOPT_SSLKEYTYPE The key type of the private SSL key specified in CURLOPT_SSLKEY. Supported key types are "PEM" (default), "DER", and "ENG".
CURLOPT_URL The URL to fetch. This can also be set when initializing a session with curl_init().
CURLOPT_USERAGENT The contents of the "User-Agent: " header to be used in a HTTP request.
CURLOPT_USERPWD A username and password formatted as "[username]:[password]" to use for the connection.

value should be an array for the following values of the option parameter:
Option Set value to Notes
CURLOPT_HTTP200ALIASES An array of HTTP 200 responses that will be treated as valid responses and not as errors. Added in cURL 7.10.3.
CURLOPT_HTTPHEADER An array of HTTP header fields to set, in the format array('Content-type: text/plain', 'Content-length: 100')
CURLOPT_POSTQUOTE An array of FTP commands to execute on the server after the FTP request has been performed.
CURLOPT_QUOTE An array of FTP commands to execute on the server prior to the FTP request.

value should be a stream resource (using fopen(), for example) for the following values of the option parameter:
Option Set value to
CURLOPT_FILE The file that the transfer should be written to. The default is STDOUT (the browser window).
CURLOPT_INFILE The file that the transfer should be read from when uploading.
CURLOPT_STDERR An alternative location to output errors to instead of STDERR.
CURLOPT_WRITEHEADER The file that the header part of the transfer is written to.

value should be the name of a valid function or a Closure for the following values of the option parameter:
Option Set value to
CURLOPT_HEADERFUNCTION A callback accepting two parameters. The first is the cURL resource, the second is a string with the header data to be written. The header data must be written when by this callback. Return the number of bytes written.
CURLOPT_PASSWDFUNCTION A callback accepting three parameters. The first is the cURL resource, the second is a string containing a password prompt, and the third is the maximum password length. Return the string containing the password.
CURLOPT_PROGRESSFUNCTION

A callback accepting five parameters. The first is the cURL resource, the second is the total number of bytes expected to be downloaded in this transfer, the third is the number of bytes downloaded so far, the fourth is the total number of bytes expected to be uploaded in this transfer, and the fifth is the number of bytes uploaded so far.

Note:

The callback is only called when the CURLOPT_NOPROGRESS option is set to FALSE.

Return a non-zero value to abort the transfer. In which case, the transfer will set a CURLE_ABORTED_BY_CALLBACK error.

CURLOPT_READFUNCTION A callback accepting three parameters. The first is the cURL resource, the second is a stream resource provided to cURL through the option CURLOPT_INFILE, and the third is the maximum amount of data to be read. The callback must return a string with a length equal or smaller than the amount of data requested, typically by reading it from the passed stream resource. It should return an empty string to signal EOF.
CURLOPT_WRITEFUNCTION A callback accepting two parameters. The first is the cURL resource, and the second is a string with the data to be written. The data must be saved by this callback. It must return the exact number of bytes written or the transfer will be aborted with an error.

Other values:
Option Set value to
CURLOPT_SHARE A result of curl_share_init(). Makes the cURL handle to use the data from the shared handle.

Return Values

Returns TRUE on success or FALSE on failure.

Changelog

Version Description
5.6.0 Removed CURLOPT_CLOSEPOLICY and associated values.
5.5.0 Added the cURL resource as the first argument to the CURLOPT_PROGRESSFUNCTION callback.
5.5.0 Introduced CURLOPT_SHARE.
5.3.0 Introduced CURLOPT_PROGRESSFUNCTION.
5.2.10 Introduced CURLOPT_PROTOCOLS, and CURLOPT_REDIR_PROTOCOLS.
5.1.0 Introduced CURLOPT_AUTOREFERER, CURLOPT_BINARYTRANSFER, CURLOPT_FTPSSLAUTH, CURLOPT_PROXYAUTH, and CURLOPT_TIMECONDITION.
5.0.0 Introduced CURLOPT_FTP_USE_EPRT, CURLOPT_NOSIGNAL, CURLOPT_UNRESTRICTED_AUTH, CURLOPT_BUFFERSIZE, CURLOPT_HTTPAUTH, CURLOPT_PROXYPORT, CURLOPT_PROXYTYPE, CURLOPT_SSLCERTTYPE, and CURLOPT_HTTP200ALIASES.

Examples

Example #1 Initializing a new cURL session and fetching a web page

<?php
// create a new cURL resource
$ch curl_init();

// set URL and other appropriate options
curl_setopt($chCURLOPT_URL"http://www.example.com/");
curl_setopt($chCURLOPT_HEADERfalse);

// grab URL and pass it to the browser
curl_exec($ch);

// close cURL resource, and free up system resources
curl_close($ch);
?>

Example #2 Uploading file

<?php

/* http://localhost/upload.php:
print_r($_POST);
print_r($_FILES);
*/

$ch curl_init();

$data = array('name' => 'Foo''file' => '@/home/user/test.png');

curl_setopt($chCURLOPT_URL'http://localhost/upload.php');
curl_setopt($chCURLOPT_POST1);
curl_setopt($chCURLOPT_POSTFIELDS$data);

curl_exec($ch);
?>

The above example will output:

Array
(
    [name] => Foo
)
Array
(
    [file] => Array
        (
            [name] => test.png
            [type] => image/png
            [tmp_name] => /tmp/phpcpjNeQ
            [error] => 0
            [size] => 279
        )

)

Notes

Note:

Passing an array to CURLOPT_POSTFIELDS will encode the data as multipart/form-data, while passing a URL-encoded string will encode the data as application/x-www-form-urlencoded.

See Also


cURL Functions
PHP Manual