Currently the most comprehensive Chinese description of CURL under PHP

CURL Function Library (Client URL Library Function) in PHP

curl_close — close a curl session
curl_copy_handle — copy all contents and parameters of a curl connection resource
curl_errno — return an error message containing the current session error The numeric number of the message
curl_error — Returns a string containing error information for the current session
curl_exec — Execute a curl session
curl_getinfo — Get information about a curl connection resource handle
curl_init — Initialize a curl session
curl_multi_add_handle — Add a separate curl handle resource to a curl batch session
curl_multi_close — Close a batch handle resource
curl_multi_exec — Parse a curl batch handle
curl_multi_getcontent — Return the text of the fetched output Stream
curl_multi_info_read — Get the relevant transmission information of the currently parsed curl
curl_multi_init — Initialize a curl batch handle resource
curl_multi_remove_handle — Remove a handle resource in the curl batch handle resource
curl_multi_select — Get all the sockets associated with the cURL extension, which can then be "selected"
curl_setopt_array — Set session parameters for a curl in the form of an array
curl_setopt — Set session parameters for a curl
curl_version — Get curl Related version information

The function of curl_init() function is to initialize a curl session. The only parameter of curl_init() function is optional and represents a URL address.
The curl_exec() function is used to execute a curl session. The only parameter is the handle returned by the curl_init() function.
The curl_close() function is used to close a curl session. The only parameter is the handle returned by the curl_init() function.

$ch = curl_init("http://www.baidu.com/");
curl_exec($ch);
curl_close($ch);
?>

The curl_version() function is used to obtain curl-related version information. The curl_version() function has a parameter. It is not clear what it does.

print_r(curl_version())
?>

The role of the curl_getinfo() function is to obtain information about a curl connection resource handle. The curl_getinfo() function has two parameters, the first parameter is the resource handle of curl, and the second parameter is the following constants:

$ch = curl_init("http://www.baidu.com/");
print_r(curl_getinfo($ch));
?>

Optional constants include:

CURLINFO_EFFECTIVE_URL
The last valid url address

CURLINFO_HTTP_CODE
The last HTTP code received

CURLINFO_FILETIME
The time when the document was retrieved remotely, if it cannot be retrieved, the return value is "-1"

CURLINFO_TOTAL_TIME
The last time Time spent on transfer

CURLINFO_NAMELOOKUP_TIME
Time spent on name resolution

CURLINFO_CONNECT_TIME
Time spent on establishing connection

CURLINFO_PRETRANSFER_TIME
From establishing connection The time it takes to prepare the transfer

CURLINFO_STARTTRANSFER_TIME
The time it takes from establishing the connection to the start of the transfer

CURLINFO_REDIRECT_TIME
The time it takes to redirect before the transaction transfer starts

CURLINFO_SIZE_UPLOAD
Total value of uploaded data

CURLINFO_SIZE_DOWNLOAD
Total value of downloaded data

CURLINFO_SPEED_DOWNLOAD
Average download speed

CURLINFO_SPEED_UPLO AD
Average upload speed

CURLINFO_HEADER_SIZE
The size of the header part

CURLINFO_HEADER_OUT
The string to send the request

CURLINFO_REQUEST_SIZE
Has in the HTTP request The size of the request in question

CURLINFO_SSL_VERIFYRESULT
Result of SSL certification verification requested by setting CURLOPT_SSL_VERIFYPEER

CURLINFO_CONTENT_LENGTH_DOWNLOAD
The download content length read from the Content-Length: field

CURLINFO_CONTENT_LENGTH_UPLOAD
Description of the size of the uploaded content

CURLINFO_CONTENT_TYPE
The "Content-type" value of the downloaded content, NULL means that the server did not send a valid "Content-Type: header"

The curl_setopt() function is used to set session parameters for a curl. The curl_setopt_array() function is used to set session parameters for a curl in the form of an array.

$ch = curl_init();
$fp = fopen("example_homepage.txt", "w");
curl_setopt($ch, CURLOPT_FILE, $ fp);
$options = array(
CURLOPT_URL => 'http://www.baidu.com/',
CURLOPT_HEADER => false
);
curl_setopt_array($ ch, $options);
curl_exec($ch);
curl_close($ch);
fclose($fp);
?>

The parameters that can be set are: :

CURLOPT_AUTOREFERER
Automatically set the referer information in the header

CURLOPT_BINARYTRANSFER
When CURLOPT_RETURNTRANSFER is enabled, data will be obtained and returned

CURLOPT_COOKIESESSION
When enabled, curl will Only pass one session cookie and ignore other cookies. By default, curl will return all cookies to the server. Session cookies refer to cookies that are used to determine whether the server-side session is valid.

CURLOPT_CRLF
When enabled, convert Unix line feed characters into carriage return and line feed characters.

CURLOPT_DNS_USE_GLOBAL_CACHE
When enabled, a global DNS cache is enabled. This item is thread-safe and defaults to true.

CURLOPT_FAILONERROR
Displays the HTTP status code. The default behavior is to ignore HTTP information with a number less than or equal to 400.

CURLOPT_FILETIME
When enabled, it will try to modify the information in the remote document. The result information will be returned through the CURLINFO_FILETIME option of the curl_getinfo() function.

CURLOPT_FOLLOWLOCATION
When enabled, the "Location:" returned by the server will be placed in the header and returned to the server recursively. Use CURLOPT_MAXREDIRS to limit the number of recursive returns.

CURLOPT_FORBID_REUSE
Forcibly disconnect after completing the interaction and cannot be reused.

CURLOPT_FRESH_CONNECT
Force a new connection to replace the one in the cache.

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.
Added in PHP 5.0.0.

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_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. >When enabled, the header file information will be output as a data stream.

CURLOPT_HTTPGET
When enabled, the HTTP method will be set to GET. Because GET is the default, it is only used when it is modified.

CURLOPT_HTTPPROXYTUNNEL
When enabled, it will be transmitted through HTTP proxy.

CURLOPT_MUTE
Restore all modified parameters in the curl function to their default values.

CURLOPT_NETRC
After the connection is established, access the ~/.netrc file to obtain the username and password information to connect to the remote site.

CURLOPT_NOBODY
When enabled, the body part of the HTML will not be output.

CURLOPT_NOPROGRESS
When enabled, turn off the progress bar of curl transmission. The default setting of this item is true

CURLOPT_NOSIGNAL
When enabled, ignore all signals passed by curl to PHP. This item is turned on by default during SAPI multi-thread transmission.

CURLOPT_POST
When enabled, a regular POST request will be sent of type: application/x-www-form-urlencoded, just like a form submission.

CURLOPT_PUT
When enabled, HTTP is allowed to send files. CURLOPT_INFILE and CURLOPT_INFILESIZE must be set at the same time.

CURLOPT_RETURNTRANSFER
The information obtained by curl_exec() is returned in the form of a file stream instead of directly output.

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. CURLOPT_SSL_VERIFYHOST may also need to be TRUE or FALSE if CURLOPT_SSL_VERIFYPEER is disabled (it defaults to 2). 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
Continuously append users to multiple locations in the header generated using CURLOPT_FOLLOWLOCATION name and password information, even if the domain name has changed.

CURLOPT_UPLOAD
Allow file transfer when enabled

CURLOPT_VERBOSE
When enabled, all information will be reported and stored in STDERR or the specified CURLOPT_STDERR

CURLOPT_BUFFERSIZE
The size of the cache is read each time the data is obtained, and this value will be filled every time.

CURLOPT_CLOSEPOLICY
It is either CURLCLOSEPOLICY_LEAST_RECENTLY_USED or CURLCLOSEPOLICY_OLDEST. There are three others, but curl does not support them yet. .

CURLOPT_CONNECTTIMEOUT
The time to wait before initiating a connection. If set to 0, there will be no waiting.

CURLOPT_DNS_CACHE_TIMEOUT
Set the time to save DNS information in memory, the default is 120 seconds.

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).

CURLOPT_HTTP_VERSION
Set the HTTP protocol used by curl, CURL_HTTP_VERSION_NONE (let curl decide by itself), CURL_HTTP_VERSION_1_0 (HTTP/1.0), CURL_HTTP_VERSION_1_1 (HTTP/1.1)

CURLOPT_HTTPAUTH
HTTP verification method used, optional value There are: CURLAUTH_BASIC, CURLAUTH_DIGEST, CURLAUTH_GSSNEGOTIATE, CURLAUTH_NTLM, CURLAUTH_ANY, CURLAUTH_ANYSAFE. You can use the "|" operator to separate multiple values. curl lets the server choose the best supported value. CURLAUTH_ANY is equivalent to CURLAUTH_BASIC | CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURL AUTH_NTLM,CURLAUTH_ANYSAFE Equivalent to CURLAUTH_DIGEST | CURLAUTH_GSSNEGOTIATE | CURLAUTH_NTLM

CURLOPT_INFILESIZE
Set the size of the uploaded file

CURLOPT_LOW_SPEED_LIMIT
When the transfer speed is less than CURLOPT_LOW_SPEED_LIMIT, PHP will LOPT_LOW_SPEED_TIME to determine whether it is too Slow and canceled transfer.

CURLOPT_LOW_SPEED_TIME
The number of seconds the transfer should be below CURLOPT_LOW_SPEED_LIMIT for PHP to consider the transfer too slow and abort. Slow and canceled transfer.

CURLOPT_MAXCONNECTS
The maximum number of connections allowed, if exceeded, CURLOPT_CLOSEPOLICY will be used to determine which connections should be stopped

CURLOPT_MAXREDIRS
Specify the maximum number of HTTP redirects, this option is the same as CURLOPT_FOLLOWLOCATION used together.

CURLOPT_PORT
An optional quantity used to specify the connection port

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.

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.

CURLOPT_RESUME_FROM
Pass a byte offset when resuming the transfer (used to resume the transfer)

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.

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
If after a certain time specified by CURLOPT_TIMEVALUE If it has been edited, CURL_TIMECOND_IFMODSINCE is used to return the page. If it has not been modified and CURLOPT_HEADER is true, a "304 Not Modified" header is returned. If CURLOPT_HEADER is false, CURL_TIMECOND_ISUNMODSINCE is used. The default value is CURL_TIMECOND_IFMODSINCE

CURLOPT_TIMEOUT
Set the maximum number of seconds curl is allowed to execute

CURLOPT_TIMEVALUE
Set a timestamp used by CURLOPT_TIMECONDITION. By default, CURL_TIMECOND_IFMODSINCE is used

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.

CURLOPT_CAPATH
A directory that holds multiple CA certificates. Use this option alongside CURLOPT_SSL_VERIFYPEER.

CURLOPT_COOKIE
Set the content of the "Set-Cookie:" part of the HTTP request.

CURLOPT_COOKIEFILE
The name of the file containing cookie information. This cookie file can be Netscape format or HTTP style header information.

CURLOPT_COOKIEJAR
After the connection is closed, the file name to store cookie information

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.html HTTP/1.0rnrn" would be incorrect.
Note: Don't do this without making sure the server supports the custom request method first.

CURLOPT_EGBSOCKET
Like CURLOPT_RANDOM_FILE, except a filename to an Entropy Gathering Daemon socket.

CURLOPT_ENCODING
The content of the "Accept-Encoding:" part in the header. The supported encoding formats are: "identity", "deflate", "gzip ".If set to an empty string, it means that all encoding formats are supported

CURLOPT_FTPPORT
The value which will be used to get the IP address to use for the FTP "POST" instruction. The "POST" 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 used in the external network interface, which can be an interface name, IP or host name.

CURLOPT_KRB4LEVEL
KRB4 (Kerberos 4) security level setting, which can be one of the following values: "clear", "safe", "confidential", "private". The default value is "private". When set to null, KRB4 is disabled. Now KRB4 security can only be used in FTP transmission.

CURLOPT_POSTFIELDS
The "POST" operation in HTTP. If you want to transfer a file, you need a file name starting with @

CURLOPT_PROXY
Set the HTTP proxy server passed through

CURLOPT_PROXYUSERPWD
To connect to the proxy server, the format is "[username ]:[password]" username and password.

CURLOPT_RANDOM_FILE
Set the file name to store the random number seeds used for SSL

CURLOPT_RANGE
Set the HTTP transmission range. You can set a transmission range in the form of "X-Y". If there are multiple HTTP transfers, use commas to separate multiple values, such as: "X-Y,N-M".

CURLOPT_REFERER
Set the value of the "Referer: " part in the header.

CURLOPT_SSL_CIPHER_LIST
A list of ciphers to use for SSL. For example, RC4-SHA and TLSv1 are valid cipher lists.

CURLOPT_SSLCERT
Pass a character containing a PEM formatted certificate string.

CURLOPT_SSLCERTPASSWD
Pass a password containing the necessary password to use the CURLOPT_SSLCERT certificate.

CURLOPT_SSLCERTTYPE
The format of the certificate. Supported formats are "PEM" (default), "DER", and "ENG".

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 address to be obtained can also be set in the curl_init() function of PHP.

CURLOPT_USERAGENT
A string containing a "user-agent" header in the HTTP request.

CURLOPT_USERPWD
Pass the username and password required for a connection in the format: "[username]:[password]".

CURLOPT_HTTP200ALIASES
The setting no longer handles HTTP 200 responses in the form of error, and the format is an array.

CURLOPT_HTTPHEADER
Set an array of transmission content in the header.

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.

CURLOPT_FILE
Set the location of the output file. The value is a resource type. The default is STDOUT (browser).

CURLOPT_INFILE
The file address that needs to be read when uploading files. The value is a resource type.

CURLOPT_STDERR
Set an error output address, the value is a resource type, replacing the default STDERR.

CURLOPT_WRITEHEADER
Set the file address where the header part is written, and the value is a resource type.

CURLOPT_HEADERFUNCTION
Set a callback function. This function has two parameters. The first is the resource handle of curl, and the second is the output header data. The output of header data must rely on this function, which returns the size of the written data.

CURLOPT_PASSWDFUNCTION
Set a callback function with three parameters. The first is the curl resource handle, the second is a password prompt, and the third parameter is the maximum allowed password length. Returns the value of the password.

CURLOPT_READFUNCTION
Set a callback function with two parameters, the first is the resource handle of curl, and the second is the read data. Data reading must rely on this function. Returns the size of the read data, such as 0 or EOF.

CURLOPT_WRITEFUNCTION
Set a callback function with two parameters, the first is the curl resource handle, and the second is the written data. Data writing must rely on this function. Return the exact size of the written data

The function of curl_copy_handle() is to copy all the contents and parameters of a curl connection resource

$ch = curl_init( "http://www.baidu.com/");
$another = curl_copy_handle($ch);
curl_exec($another);
curl_close($another);
?>

The function of curl_error() function is to return a string containing error information of the current session.
The function of curl_errno() is to return a numeric number containing error information of the current session.

The curl_multi_init() function is used to initialize a curl batch handle resource.
The curl_multi_add_handle() function is used to add individual curl handle resources to the curl batch session. The curl_multi_add_handle() function has two parameters. The first parameter represents a curl batch handle resource, and the second parameter represents a separate curl handle resource.
The function of the curl_multi_exec() function is to parse a curl batch handle. The curl_multi_exec() function has two parameters. The first parameter represents a batch handle resource, and the second parameter is a reference value parameter, indicating the remaining The number of individual curl handle resources that need to be processed.
The curl_multi_remove_handle() function represents the removal of a handle resource in the curl batch handle resource. The curl_multi_remove_handle() function has two parameters. The first parameter represents a curl batch handle resource, and the second parameter represents a separate The curl handle resource.
The curl_multi_close() function is used to close a batch handle resource.

$ch1 = curl_init();
$ch2 = curl_init();
curl_setopt($ch1, CURLOPT_URL, "http://www.baidu.com /");
curl_setopt($ch1, CURLOPT_HEADER, 0);
curl_setopt($ch2, CURLOPT_URL, "http://www.google.com/");
curl_setopt($ch2, CURLOPT_HEADER , 0);
$mh = curl_multi_init();
curl_multi_add_handle($mh,$ch1);
curl_multi_add_handle($mh,$ch2);
do {
curl_multi_exec($mh ,$flag);
} while ($flag > 0);
curl_multi_remove_handle($mh,$ch1);
curl_multi_remove_handle($mh,$ch2);
curl_multi_close($mh) ;
?>

The function of the curl_multi_getcontent() function is to return the obtained output text stream when CURLOPT_RETURNTRANSFER is set.

The curl_multi_info_read() function is used to obtain the relevant transmission information of the currently parsed curl.

curl_multi_select()
Get all the sockets associated with the cURL extension, which can then be "selected"

Currently the most comprehensive Chinese description of CURL under PHP_PHP Tutorial