curl/docs/libcurl/curl_easy_setopt.3

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.TH curl_easy_setopt 3 "25 Jun 2014" "libcurl" "libcurl"
.SH NAME
curl_easy_setopt \- set options for a curl easy handle
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLoption option, parameter);
.fi
.SH DESCRIPTION
\fIcurl_easy_setopt(3)\fP is used to tell libcurl how to behave. By setting
the appropriate options, the application can change libcurl's behavior. All
options are set with an \fIoption\fP followed by a \fIparameter\fP. That
parameter can be a \fBlong\fP, a \fBfunction pointer\fP, an \fBobject
pointer\fP or a \fBcurl_off_t\fP, 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 \fIcurl_easy_setopt(3)\fP calls in the setup phase.

Options set with this function call are valid for all forthcoming transfers
performed using this \fIhandle\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. You can optionally reset all
options back to internal default with \fIcurl_easy_reset(3)\fP.

Strings passed to libcurl as 'char *' arguments, are copied by the library;
the string storage associated to the pointer argument may be discarded or
reused after \fIcurl_easy_setopt(3)\fP returns. The only exception to this
rule is really \fICURLOPT_POSTFIELDS(3)\fP, but the alternative that copies
the string \fICURLOPT_COPYPOSTFIELDS(3)\fP has some usage characteristics you
need to read up on. This function does not accept input strings longer than
\fBCURL_MAX_INPUT_LENGTH\fP (8 MB).

The order in which the options are set does not matter.

Before version 7.17.0, strings were not copied. Instead the user was forced
keep them available until libcurl no longer needed them.

The \fIhandle\fP is the return code from a \fIcurl_easy_init(3)\fP or
\fIcurl_easy_duphandle(3)\fP call.
.SH BEHAVIOR OPTIONS
.IP CURLOPT_VERBOSE
Display verbose information. See \fICURLOPT_VERBOSE(3)\fP
.IP CURLOPT_HEADER
Include the header in the body output. See \fICURLOPT_HEADER(3)\fP
.IP CURLOPT_NOPROGRESS
Shut off the progress meter. See \fICURLOPT_NOPROGRESS(3)\fP
.IP CURLOPT_NOSIGNAL
Do not install signal handlers. See \fICURLOPT_NOSIGNAL(3)\fP
.IP CURLOPT_WILDCARDMATCH
Transfer multiple files according to a file name pattern. See \fICURLOPT_WILDCARDMATCH(3)\fP
.SH CALLBACK OPTIONS
.IP CURLOPT_WRITEFUNCTION
Callback for writing data. See \fICURLOPT_WRITEFUNCTION(3)\fP
.IP CURLOPT_WRITEDATA
Data pointer to pass to the write callback. See \fICURLOPT_WRITEDATA(3)\fP
.IP CURLOPT_READFUNCTION
Callback for reading data. See \fICURLOPT_READFUNCTION(3)\fP
.IP CURLOPT_READDATA
Data pointer to pass to the read callback. See \fICURLOPT_READDATA(3)\fP
.IP CURLOPT_IOCTLFUNCTION
\fBDeprecated option\fP Callback for I/O operations.
See \fICURLOPT_IOCTLFUNCTION(3)\fP
.IP CURLOPT_IOCTLDATA
\fBDeprecated option\fP Data pointer to pass to the I/O callback.
See \fICURLOPT_IOCTLDATA(3)\fP
.IP CURLOPT_SEEKFUNCTION
Callback for seek operations. See \fICURLOPT_SEEKFUNCTION(3)\fP
.IP CURLOPT_SEEKDATA
Data pointer to pass to the seek callback. See \fICURLOPT_SEEKDATA(3)\fP
.IP CURLOPT_SOCKOPTFUNCTION
Callback for sockopt operations. See \fICURLOPT_SOCKOPTFUNCTION(3)\fP
.IP CURLOPT_SOCKOPTDATA
Data pointer to pass to the sockopt callback. See \fICURLOPT_SOCKOPTDATA(3)\fP
.IP CURLOPT_OPENSOCKETFUNCTION
Callback for socket creation. See \fICURLOPT_OPENSOCKETFUNCTION(3)\fP
.IP CURLOPT_OPENSOCKETDATA
Data pointer to pass to the open socket callback. See \fICURLOPT_OPENSOCKETDATA(3)\fP
.IP CURLOPT_CLOSESOCKETFUNCTION
Callback for closing socket. See \fICURLOPT_CLOSESOCKETFUNCTION(3)\fP
.IP CURLOPT_CLOSESOCKETDATA
Data pointer to pass to the close socket callback. See \fICURLOPT_CLOSESOCKETDATA(3)\fP
.IP CURLOPT_PROGRESSFUNCTION
\fBOBSOLETE\fP callback for progress meter.
See \fICURLOPT_PROGRESSFUNCTION(3)\fP
.IP CURLOPT_PROGRESSDATA
Data pointer to pass to the progress meter callback. See \fICURLOPT_PROGRESSDATA(3)\fP
.IP CURLOPT_XFERINFOFUNCTION
Callback for progress meter. See \fICURLOPT_XFERINFOFUNCTION(3)\fP
.IP CURLOPT_XFERINFODATA
Data pointer to pass to the progress meter callback. See \fICURLOPT_XFERINFODATA(3)\fP
.IP CURLOPT_HEADERFUNCTION
Callback for writing received headers. See \fICURLOPT_HEADERFUNCTION(3)\fP
.IP CURLOPT_HEADERDATA
Data pointer to pass to the header callback. See \fICURLOPT_HEADERDATA(3)\fP
.IP CURLOPT_DEBUGFUNCTION
Callback for debug information. See \fICURLOPT_DEBUGFUNCTION(3)\fP
.IP CURLOPT_DEBUGDATA
Data pointer to pass to the debug callback. See \fICURLOPT_DEBUGDATA(3)\fP
.IP CURLOPT_SSL_CTX_FUNCTION
Callback for SSL context logic. See \fICURLOPT_SSL_CTX_FUNCTION(3)\fP
.IP CURLOPT_SSL_CTX_DATA
Data pointer to pass to the SSL context callback. See \fICURLOPT_SSL_CTX_DATA(3)\fP
.IP CURLOPT_CONV_TO_NETWORK_FUNCTION
\fBOBSOLETE\fP Callback for code base conversion.
See \fICURLOPT_CONV_TO_NETWORK_FUNCTION(3)\fP
.IP CURLOPT_CONV_FROM_NETWORK_FUNCTION
\fBOBSOLETE\fP Callback for code base conversion.
See \fICURLOPT_CONV_FROM_NETWORK_FUNCTION(3)\fP
.IP CURLOPT_CONV_FROM_UTF8_FUNCTION
\fBOBSOLETE\fP Callback for code base conversion.
See \fICURLOPT_CONV_FROM_UTF8_FUNCTION(3)\fP
.IP CURLOPT_INTERLEAVEFUNCTION
Callback for RTSP interleaved data. See \fICURLOPT_INTERLEAVEFUNCTION(3)\fP
.IP CURLOPT_INTERLEAVEDATA
Data pointer to pass to the RTSP interleave callback. See \fICURLOPT_INTERLEAVEDATA(3)\fP
.IP CURLOPT_CHUNK_BGN_FUNCTION
Callback for wildcard download start of chunk. See \fICURLOPT_CHUNK_BGN_FUNCTION(3)\fP
.IP CURLOPT_CHUNK_END_FUNCTION
Callback for wildcard download end of chunk. See \fICURLOPT_CHUNK_END_FUNCTION(3)\fP
.IP CURLOPT_CHUNK_DATA
Data pointer to pass to the chunk callbacks. See \fICURLOPT_CHUNK_DATA(3)\fP
.IP CURLOPT_FNMATCH_FUNCTION
Callback for wildcard matching. See \fICURLOPT_FNMATCH_FUNCTION(3)\fP
.IP CURLOPT_FNMATCH_DATA
Data pointer to pass to the wildcard matching callback. See \fICURLOPT_FNMATCH_DATA(3)\fP
.IP CURLOPT_SUPPRESS_CONNECT_HEADERS
Suppress proxy CONNECT response headers from user callbacks. See \fICURLOPT_SUPPRESS_CONNECT_HEADERS(3)\fP
.IP CURLOPT_RESOLVER_START_FUNCTION
Callback to be called before a new resolve request is started. See \fICURLOPT_RESOLVER_START_FUNCTION(3)\fP
.IP CURLOPT_RESOLVER_START_DATA
Data pointer to pass to resolver start callback. See \fICURLOPT_RESOLVER_START_DATA(3)\fP
.IP CURLOPT_PREREQFUNCTION
Callback to be called after a connection is established but before a request is made on that connection. See \fICURLOPT_PREREQFUNCTION(3)\fP
.IP CURLOPT_PREREQDATA
Data pointer to pass to the CURLOPT_PREREQFUNCTION callback. See \fICURLOPT_PREREQDATA(3)\fP
.SH ERROR OPTIONS
.IP CURLOPT_ERRORBUFFER
Error message buffer. See \fICURLOPT_ERRORBUFFER(3)\fP
.IP CURLOPT_STDERR
stderr replacement stream. See \fICURLOPT_STDERR(3)\fP
.IP CURLOPT_FAILONERROR
Fail on HTTP 4xx errors. \fICURLOPT_FAILONERROR(3)\fP
.IP CURLOPT_KEEP_SENDING_ON_ERROR
Keep sending on HTTP >= 300 errors. \fICURLOPT_KEEP_SENDING_ON_ERROR(3)\fP
.SH NETWORK OPTIONS
.IP CURLOPT_URL
URL to work on. See \fICURLOPT_URL(3)\fP
.IP CURLOPT_PATH_AS_IS
Disable squashing /../ and /./ sequences in the path. See \fICURLOPT_PATH_AS_IS(3)\fP
.IP CURLOPT_PROTOCOLS
\fBDeprecated option\fP Allowed protocols. See \fICURLOPT_PROTOCOLS(3)\fP
.IP CURLOPT_PROTOCOLS_STR
Allowed protocols. See \fICURLOPT_PROTOCOLS_STR(3)\fP
.IP CURLOPT_REDIR_PROTOCOLS
\fBDeprecated option\fP Protocols to allow redirects to. See
\fICURLOPT_REDIR_PROTOCOLS(3)\fP
.IP CURLOPT_REDIR_PROTOCOLS_STR
Protocols to allow redirects to. See \fICURLOPT_REDIR_PROTOCOLS_STR(3)\fP
.IP CURLOPT_DEFAULT_PROTOCOL
Default protocol. See \fICURLOPT_DEFAULT_PROTOCOL(3)\fP
.IP CURLOPT_PROXY
Proxy to use. See \fICURLOPT_PROXY(3)\fP
.IP CURLOPT_PRE_PROXY
Socks proxy to use. See \fICURLOPT_PRE_PROXY(3)\fP
.IP CURLOPT_PROXYPORT
Proxy port to use. See \fICURLOPT_PROXYPORT(3)\fP
.IP CURLOPT_PROXYTYPE
Proxy type. See \fICURLOPT_PROXYTYPE(3)\fP
.IP CURLOPT_NOPROXY
Filter out hosts from proxy use. \fICURLOPT_NOPROXY(3)\fP
.IP CURLOPT_HTTPPROXYTUNNEL
Tunnel through the HTTP proxy. \fICURLOPT_HTTPPROXYTUNNEL(3)\fP
.IP CURLOPT_CONNECT_TO
Connect to a specific host and port. See \fICURLOPT_CONNECT_TO(3)\fP
.IP CURLOPT_SOCKS5_AUTH
Socks5 authentication methods. See \fICURLOPT_SOCKS5_AUTH(3)\fP
.IP CURLOPT_SOCKS5_GSSAPI_SERVICE
\fBDeprecated option\fP Socks5 GSSAPI service name.
See \fICURLOPT_SOCKS5_GSSAPI_SERVICE(3)\fP
.IP CURLOPT_SOCKS5_GSSAPI_NEC
Socks5 GSSAPI NEC mode. See \fICURLOPT_SOCKS5_GSSAPI_NEC(3)\fP
.IP CURLOPT_PROXY_SERVICE_NAME
Proxy authentication service name. \fICURLOPT_PROXY_SERVICE_NAME(3)\fP
.IP CURLOPT_HAPROXYPROTOCOL
Send an HAProxy PROXY protocol v1 header. See \fICURLOPT_HAPROXYPROTOCOL(3)\fP
.IP CURLOPT_HAPROXY_CLIENT_IP
Spoof the client IP in an HAProxy PROXY protocol v1 header. See \fICURLOPT_HAPROXY_CLIENT_IP(3)\fP
.IP CURLOPT_SERVICE_NAME
Authentication service name. \fICURLOPT_SERVICE_NAME(3)\fP
.IP CURLOPT_INTERFACE
Bind connection locally to this. See \fICURLOPT_INTERFACE(3)\fP
.IP CURLOPT_LOCALPORT
Bind connection locally to this port. See \fICURLOPT_LOCALPORT(3)\fP
.IP CURLOPT_LOCALPORTRANGE
Bind connection locally to port range. See \fICURLOPT_LOCALPORTRANGE(3)\fP
.IP CURLOPT_DNS_CACHE_TIMEOUT
Timeout for DNS cache. See \fICURLOPT_DNS_CACHE_TIMEOUT(3)\fP
.IP CURLOPT_DNS_USE_GLOBAL_CACHE
\fBOBSOLETE\fP Enable global DNS cache.
See \fICURLOPT_DNS_USE_GLOBAL_CACHE(3)\fP
.IP CURLOPT_DOH_URL
Use this DoH server for name resolves. See \fICURLOPT_DOH_URL(3)\fP
.IP CURLOPT_BUFFERSIZE
Ask for alternate buffer size. See \fICURLOPT_BUFFERSIZE(3)\fP
.IP CURLOPT_PORT
Port number to connect to. See \fICURLOPT_PORT(3)\fP
.IP CURLOPT_TCP_FASTOPEN
Enable TCP Fast Open. See \fICURLOPT_TCP_FASTOPEN(3)\fP
.IP CURLOPT_TCP_NODELAY
Disable the Nagle algorithm. See \fICURLOPT_TCP_NODELAY(3)\fP
.IP CURLOPT_ADDRESS_SCOPE
IPv6 scope for local addresses. See \fICURLOPT_ADDRESS_SCOPE(3)\fP
.IP CURLOPT_TCP_KEEPALIVE
Enable TCP keep-alive. See \fICURLOPT_TCP_KEEPALIVE(3)\fP
.IP CURLOPT_TCP_KEEPIDLE
Idle time before sending keep-alive. See \fICURLOPT_TCP_KEEPIDLE(3)\fP
.IP CURLOPT_TCP_KEEPINTVL
Interval between keep-alive probes. See \fICURLOPT_TCP_KEEPINTVL(3)\fP
.IP CURLOPT_UNIX_SOCKET_PATH
Path to a Unix domain socket. See \fICURLOPT_UNIX_SOCKET_PATH(3)\fP
.IP CURLOPT_ABSTRACT_UNIX_SOCKET
Path to an abstract Unix domain socket. See \fICURLOPT_ABSTRACT_UNIX_SOCKET(3)\fP
.SH NAMES and PASSWORDS OPTIONS (Authentication)
.IP CURLOPT_NETRC
Enable .netrc parsing. See \fICURLOPT_NETRC(3)\fP
.IP CURLOPT_NETRC_FILE
\&.netrc file name. See \fICURLOPT_NETRC_FILE(3)\fP
.IP CURLOPT_USERPWD
User name and password. See \fICURLOPT_USERPWD(3)\fP
.IP CURLOPT_PROXYUSERPWD
Proxy user name and password. See \fICURLOPT_PROXYUSERPWD(3)\fP
.IP CURLOPT_USERNAME
User name. See \fICURLOPT_USERNAME(3)\fP
.IP CURLOPT_PASSWORD
Password. See \fICURLOPT_PASSWORD(3)\fP
.IP CURLOPT_LOGIN_OPTIONS
Login options. See \fICURLOPT_LOGIN_OPTIONS(3)\fP
.IP CURLOPT_PROXYUSERNAME
Proxy user name. See \fICURLOPT_PROXYUSERNAME(3)\fP
.IP CURLOPT_PROXYPASSWORD
Proxy password. See \fICURLOPT_PROXYPASSWORD(3)\fP
.IP CURLOPT_HTTPAUTH
HTTP server authentication methods. See \fICURLOPT_HTTPAUTH(3)\fP
.IP CURLOPT_TLSAUTH_USERNAME
TLS authentication user name. See \fICURLOPT_TLSAUTH_USERNAME(3)\fP
.IP CURLOPT_PROXY_TLSAUTH_USERNAME
Proxy TLS authentication user name. See \fICURLOPT_PROXY_TLSAUTH_USERNAME(3)\fP
.IP CURLOPT_TLSAUTH_PASSWORD
TLS authentication password. See \fICURLOPT_TLSAUTH_PASSWORD(3)\fP
.IP CURLOPT_PROXY_TLSAUTH_PASSWORD
Proxy TLS authentication password. See \fICURLOPT_PROXY_TLSAUTH_PASSWORD(3)\fP
.IP CURLOPT_TLSAUTH_TYPE
TLS authentication methods. See \fICURLOPT_TLSAUTH_TYPE(3)\fP
.IP CURLOPT_PROXY_TLSAUTH_TYPE
Proxy TLS authentication methods. See \fICURLOPT_PROXY_TLSAUTH_TYPE(3)\fP
.IP CURLOPT_PROXYAUTH
HTTP proxy authentication methods. See \fICURLOPT_PROXYAUTH(3)\fP
.IP CURLOPT_SASL_AUTHZID
SASL authorization identity (identity to act as). See \fICURLOPT_SASL_AUTHZID(3)\fP
.IP CURLOPT_SASL_IR
Enable SASL initial response. See \fICURLOPT_SASL_IR(3)\fP
.IP CURLOPT_XOAUTH2_BEARER
OAuth2 bearer token. See \fICURLOPT_XOAUTH2_BEARER(3)\fP
.IP CURLOPT_DISALLOW_USERNAME_IN_URL
Do not allow username in URL. See \fICURLOPT_DISALLOW_USERNAME_IN_URL(3)\fP
.SH HTTP OPTIONS
.IP CURLOPT_AUTOREFERER
Automatically set Referer: header. See \fICURLOPT_AUTOREFERER(3)\fP
.IP CURLOPT_ACCEPT_ENCODING
Accept-Encoding and automatic decompressing data. See \fICURLOPT_ACCEPT_ENCODING(3)\fP
.IP CURLOPT_TRANSFER_ENCODING
Request Transfer-Encoding. See \fICURLOPT_TRANSFER_ENCODING(3)\fP
.IP CURLOPT_FOLLOWLOCATION
Follow HTTP redirects. See \fICURLOPT_FOLLOWLOCATION(3)\fP
.IP CURLOPT_UNRESTRICTED_AUTH
Do not restrict authentication to original host. \fICURLOPT_UNRESTRICTED_AUTH(3)\fP
.IP CURLOPT_MAXREDIRS
Maximum number of redirects to follow. See \fICURLOPT_MAXREDIRS(3)\fP
.IP CURLOPT_POSTREDIR
How to act on redirects after POST. See \fICURLOPT_POSTREDIR(3)\fP
.IP CURLOPT_PUT
\fBDeprecated option\fP Issue an HTTP PUT request. See \fICURLOPT_PUT(3)\fP
.IP CURLOPT_POST
Issue an HTTP POST request. See \fICURLOPT_POST(3)\fP
.IP CURLOPT_POSTFIELDS
Send a POST with this data. See \fICURLOPT_POSTFIELDS(3)\fP
.IP CURLOPT_POSTFIELDSIZE
The POST data is this big. See \fICURLOPT_POSTFIELDSIZE(3)\fP
.IP CURLOPT_POSTFIELDSIZE_LARGE
The POST data is this big. See \fICURLOPT_POSTFIELDSIZE_LARGE(3)\fP
.IP CURLOPT_COPYPOSTFIELDS
Send a POST with this data - and copy it. See \fICURLOPT_COPYPOSTFIELDS(3)\fP
.IP CURLOPT_HTTPPOST
\fBDeprecated option\fP Multipart formpost HTTP POST.
See \fICURLOPT_HTTPPOST(3)\fP
.IP CURLOPT_REFERER
Referer: header. See \fICURLOPT_REFERER(3)\fP
.IP CURLOPT_USERAGENT
User-Agent: header. See \fICURLOPT_USERAGENT(3)\fP
.IP CURLOPT_HTTPHEADER
Custom HTTP headers. See \fICURLOPT_HTTPHEADER(3)\fP
.IP CURLOPT_HEADEROPT
Control custom headers. See \fICURLOPT_HEADEROPT(3)\fP
.IP CURLOPT_PROXYHEADER
Custom HTTP headers sent to proxy. See \fICURLOPT_PROXYHEADER(3)\fP
.IP CURLOPT_HTTP200ALIASES
Alternative versions of 200 OK. See \fICURLOPT_HTTP200ALIASES(3)\fP
.IP CURLOPT_COOKIE
Cookie(s) to send. See \fICURLOPT_COOKIE(3)\fP
.IP CURLOPT_COOKIEFILE
File to read cookies from. See \fICURLOPT_COOKIEFILE(3)\fP
.IP CURLOPT_COOKIEJAR
File to write cookies to. See \fICURLOPT_COOKIEJAR(3)\fP
.IP CURLOPT_COOKIESESSION
Start a new cookie session. See \fICURLOPT_COOKIESESSION(3)\fP
.IP CURLOPT_COOKIELIST
Add or control cookies. See \fICURLOPT_COOKIELIST(3)\fP
.IP CURLOPT_ALTSVC
Specify the Alt-Svc: cache file name. See \fICURLOPT_ALTSVC(3)\fP
.IP CURLOPT_ALTSVC_CTRL
Enable and configure Alt-Svc: treatment. See \fICURLOPT_ALTSVC_CTRL(3)\fP
.IP CURLOPT_HSTS
Set HSTS cache file. See \fICURLOPT_HSTS(3)\fP
.IP CURLOPT_HSTS_CTRL
Enable HSTS. See \fICURLOPT_HSTS_CTRL(3)\fP
.IP CURLOPT_HSTSREADFUNCTION
Set HSTS read callback. See \fICURLOPT_HSTSREADFUNCTION(3)\fP
.IP CURLOPT_HSTSREADDATA
Pass pointer to the HSTS read callback. See \fICURLOPT_HSTSREADDATA(3)\fP
.IP CURLOPT_HSTSWRITEFUNCTION
Set HSTS write callback. See \fICURLOPT_HSTSWRITEFUNCTION(3)\fP
.IP CURLOPT_HSTSWRITEDATA
Pass pointer to the HSTS write callback. See \fICURLOPT_HSTSWRITEDATA(3)\fP
.IP CURLOPT_HTTPGET
Do an HTTP GET request. See \fICURLOPT_HTTPGET(3)\fP
.IP CURLOPT_REQUEST_TARGET
Set the request target. \fICURLOPT_REQUEST_TARGET(3)\fP
.IP CURLOPT_HTTP_VERSION
HTTP version to use. \fICURLOPT_HTTP_VERSION(3)\fP
.IP CURLOPT_HTTP09_ALLOWED
Allow HTTP/0.9 responses. \fICURLOPT_HTTP09_ALLOWED(3)\fP
.IP CURLOPT_IGNORE_CONTENT_LENGTH
Ignore Content-Length. See \fICURLOPT_IGNORE_CONTENT_LENGTH(3)\fP
.IP CURLOPT_HTTP_CONTENT_DECODING
Disable Content decoding. See \fICURLOPT_HTTP_CONTENT_DECODING(3)\fP
.IP CURLOPT_HTTP_TRANSFER_DECODING
Disable Transfer decoding. See \fICURLOPT_HTTP_TRANSFER_DECODING(3)\fP
.IP CURLOPT_EXPECT_100_TIMEOUT_MS
100-continue timeout. See \fICURLOPT_EXPECT_100_TIMEOUT_MS(3)\fP
.IP CURLOPT_TRAILERFUNCTION
Set callback for sending trailing headers. See
\fICURLOPT_TRAILERFUNCTION(3)\fP
.IP CURLOPT_TRAILERDATA
Custom pointer passed to the trailing headers callback. See
\fICURLOPT_TRAILERDATA(3)\fP
.IP CURLOPT_PIPEWAIT
Wait on connection to pipeline on it. See \fICURLOPT_PIPEWAIT(3)\fP
.IP CURLOPT_STREAM_DEPENDS
This HTTP/2 stream depends on another. See \fICURLOPT_STREAM_DEPENDS(3)\fP
.IP CURLOPT_STREAM_DEPENDS_E
This HTTP/2 stream depends on another exclusively. See
\fICURLOPT_STREAM_DEPENDS_E(3)\fP
.IP CURLOPT_STREAM_WEIGHT
Set this HTTP/2 stream's weight. See \fICURLOPT_STREAM_WEIGHT(3)\fP
.SH SMTP OPTIONS
.IP CURLOPT_MAIL_FROM
Address of the sender. See \fICURLOPT_MAIL_FROM(3)\fP
.IP CURLOPT_MAIL_RCPT
Address of the recipients. See \fICURLOPT_MAIL_RCPT(3)\fP
.IP CURLOPT_MAIL_AUTH
Authentication address. See \fICURLOPT_MAIL_AUTH(3)\fP
.IP CURLOPT_MAIL_RCPT_ALLOWFAILS
Allow RCPT TO command to fail for some recipients. See
\fICURLOPT_MAIL_RCPT_ALLOWFAILS(3)\fP
.SH TFTP OPTIONS
.IP CURLOPT_TFTP_BLKSIZE
TFTP block size. See \fICURLOPT_TFTP_BLKSIZE(3)\fP
.IP CURLOPT_TFTP_NO_OPTIONS
Do not send TFTP options requests. See \fICURLOPT_TFTP_NO_OPTIONS(3)\fP
.SH FTP OPTIONS
.IP CURLOPT_FTPPORT
Use active FTP. See \fICURLOPT_FTPPORT(3)\fP
.IP CURLOPT_QUOTE
Commands to run before transfer. See \fICURLOPT_QUOTE(3)\fP
.IP CURLOPT_POSTQUOTE
Commands to run after transfer. See \fICURLOPT_POSTQUOTE(3)\fP
.IP CURLOPT_PREQUOTE
Commands to run just before transfer. See \fICURLOPT_PREQUOTE(3)\fP
.IP CURLOPT_APPEND
Append to remote file. See \fICURLOPT_APPEND(3)\fP
.IP CURLOPT_FTP_USE_EPRT
Use EPRT. See \fICURLOPT_FTP_USE_EPRT(3)\fP
.IP CURLOPT_FTP_USE_EPSV
Use EPSV. See \fICURLOPT_FTP_USE_EPSV(3)\fP
.IP CURLOPT_FTP_USE_PRET
Use PRET. See \fICURLOPT_FTP_USE_PRET(3)\fP
.IP CURLOPT_FTP_CREATE_MISSING_DIRS
Create missing directories on the remote server. See \fICURLOPT_FTP_CREATE_MISSING_DIRS(3)\fP
.IP CURLOPT_SERVER_RESPONSE_TIMEOUT
Timeout for server responses. See \fICURLOPT_SERVER_RESPONSE_TIMEOUT(3)\fP
.IP CURLOPT_SERVER_RESPONSE_TIMEOUT_MS
Timeout for server responses. See \fICURLOPT_SERVER_RESPONSE_TIMEOUT_MS(3)\fP
.IP CURLOPT_FTP_ALTERNATIVE_TO_USER
Alternative to USER. See \fICURLOPT_FTP_ALTERNATIVE_TO_USER(3)\fP
.IP CURLOPT_FTP_SKIP_PASV_IP
Ignore the IP address in the PASV response. See \fICURLOPT_FTP_SKIP_PASV_IP(3)\fP
.IP CURLOPT_FTPSSLAUTH
Control how to do TLS. See \fICURLOPT_FTPSSLAUTH(3)\fP
.IP CURLOPT_FTP_SSL_CCC
Back to non-TLS again after authentication. See \fICURLOPT_FTP_SSL_CCC(3)\fP
.IP CURLOPT_FTP_ACCOUNT
Send ACCT command. See \fICURLOPT_FTP_ACCOUNT(3)\fP
.IP CURLOPT_FTP_FILEMETHOD
Specify how to reach files. See \fICURLOPT_FTP_FILEMETHOD(3)\fP
.SH RTSP OPTIONS
.IP CURLOPT_RTSP_REQUEST
RTSP request. See \fICURLOPT_RTSP_REQUEST(3)\fP
.IP CURLOPT_RTSP_SESSION_ID
RTSP session-id. See \fICURLOPT_RTSP_SESSION_ID(3)\fP
.IP CURLOPT_RTSP_STREAM_URI
RTSP stream URI. See \fICURLOPT_RTSP_STREAM_URI(3)\fP
.IP CURLOPT_RTSP_TRANSPORT
RTSP Transport: header. See \fICURLOPT_RTSP_TRANSPORT(3)\fP
.IP CURLOPT_RTSP_CLIENT_CSEQ
Client CSEQ number. See \fICURLOPT_RTSP_CLIENT_CSEQ(3)\fP
.IP CURLOPT_RTSP_SERVER_CSEQ
CSEQ number for RTSP Server->Client request. See \fICURLOPT_RTSP_SERVER_CSEQ(3)\fP
.IP CURLOPT_AWS_SIGV4
AWS HTTP V4 Signature. See \fICURLOPT_AWS_SIGV4(3)\fP
.SH PROTOCOL OPTIONS
.IP CURLOPT_TRANSFERTEXT
Use text transfer. See \fICURLOPT_TRANSFERTEXT(3)\fP
.IP CURLOPT_PROXY_TRANSFER_MODE
Add transfer mode to URL over proxy. See \fICURLOPT_PROXY_TRANSFER_MODE(3)\fP
.IP CURLOPT_CRLF
Convert newlines. See \fICURLOPT_CRLF(3)\fP
.IP CURLOPT_RANGE
Range requests. See \fICURLOPT_RANGE(3)\fP
.IP CURLOPT_RESUME_FROM
Resume a transfer. See \fICURLOPT_RESUME_FROM(3)\fP
.IP CURLOPT_RESUME_FROM_LARGE
Resume a transfer. See \fICURLOPT_RESUME_FROM_LARGE(3)\fP
.IP CURLOPT_CURLU
Set URL to work on with a URL handle. See \fICURLOPT_CURLU(3)\fP
.IP CURLOPT_CUSTOMREQUEST
Custom request/method. See \fICURLOPT_CUSTOMREQUEST(3)\fP
.IP CURLOPT_FILETIME
Request file modification date and time. See \fICURLOPT_FILETIME(3)\fP
.IP CURLOPT_DIRLISTONLY
List only. See \fICURLOPT_DIRLISTONLY(3)\fP
.IP CURLOPT_NOBODY
Do not get the body contents. See \fICURLOPT_NOBODY(3)\fP
.IP CURLOPT_INFILESIZE
Size of file to send. \fICURLOPT_INFILESIZE(3)\fP
.IP CURLOPT_INFILESIZE_LARGE
Size of file to send. \fICURLOPT_INFILESIZE_LARGE(3)\fP
.IP CURLOPT_UPLOAD
Upload data. See \fICURLOPT_UPLOAD(3)\fP
.IP CURLOPT_UPLOAD_BUFFERSIZE
Set upload buffer size. See \fICURLOPT_UPLOAD_BUFFERSIZE(3)\fP
.IP CURLOPT_MIMEPOST
Post/send MIME data. See \fICURLOPT_MIMEPOST(3)\fP
.IP CURLOPT_MIME_OPTIONS
Set MIME option flags. See \fICURLOPT_MIME_OPTIONS(3)\fP
.IP CURLOPT_MAXFILESIZE
Maximum file size to get. See \fICURLOPT_MAXFILESIZE(3)\fP
.IP CURLOPT_MAXFILESIZE_LARGE
Maximum file size to get. See \fICURLOPT_MAXFILESIZE_LARGE(3)\fP
.IP CURLOPT_TIMECONDITION
Make a time conditional request. See \fICURLOPT_TIMECONDITION(3)\fP
.IP CURLOPT_TIMEVALUE
Time value for the time conditional request. See \fICURLOPT_TIMEVALUE(3)\fP
.IP CURLOPT_TIMEVALUE_LARGE
Time value for the time conditional request. See \fICURLOPT_TIMEVALUE_LARGE(3)\fP
.SH CONNECTION OPTIONS
.IP CURLOPT_TIMEOUT
Timeout for the entire request. See \fICURLOPT_TIMEOUT(3)\fP
.IP CURLOPT_TIMEOUT_MS
Millisecond timeout for the entire request. See \fICURLOPT_TIMEOUT_MS(3)\fP
.IP CURLOPT_LOW_SPEED_LIMIT
Low speed limit to abort transfer. See \fICURLOPT_LOW_SPEED_LIMIT(3)\fP
.IP CURLOPT_LOW_SPEED_TIME
Time to be below the speed to trigger low speed abort. See \fICURLOPT_LOW_SPEED_TIME(3)\fP
.IP CURLOPT_MAX_SEND_SPEED_LARGE
Cap the upload speed to this. See \fICURLOPT_MAX_SEND_SPEED_LARGE(3)\fP
.IP CURLOPT_MAX_RECV_SPEED_LARGE
Cap the download speed to this. See \fICURLOPT_MAX_RECV_SPEED_LARGE(3)\fP
.IP CURLOPT_MAXCONNECTS
Maximum number of connections in the connection pool. See \fICURLOPT_MAXCONNECTS(3)\fP
.IP CURLOPT_FRESH_CONNECT
Use a new connection. \fICURLOPT_FRESH_CONNECT(3)\fP
.IP CURLOPT_FORBID_REUSE
Prevent subsequent connections from reusing this. See \fICURLOPT_FORBID_REUSE(3)\fP
.IP CURLOPT_MAXAGE_CONN
Limit the age (idle time) of connections for reuse. See \fICURLOPT_MAXAGE_CONN(3)\fP
.IP CURLOPT_MAXLIFETIME_CONN
Limit the age (since creation) of connections for reuse. See \fICURLOPT_MAXLIFETIME_CONN(3)\fP
.IP CURLOPT_CONNECTTIMEOUT
Timeout for the connection phase. See \fICURLOPT_CONNECTTIMEOUT(3)\fP
.IP CURLOPT_CONNECTTIMEOUT_MS
Millisecond timeout for the connection phase. See \fICURLOPT_CONNECTTIMEOUT_MS(3)\fP
.IP CURLOPT_IPRESOLVE
IP version to use. See \fICURLOPT_IPRESOLVE(3)\fP
.IP CURLOPT_CONNECT_ONLY
Only connect, nothing else. See \fICURLOPT_CONNECT_ONLY(3)\fP
.IP CURLOPT_USE_SSL
Use TLS/SSL. See \fICURLOPT_USE_SSL(3)\fP
.IP CURLOPT_RESOLVE
Provide fixed/fake name resolves. See \fICURLOPT_RESOLVE(3)\fP
.IP CURLOPT_DNS_INTERFACE
Bind name resolves to this interface. See \fICURLOPT_DNS_INTERFACE(3)\fP
.IP CURLOPT_DNS_LOCAL_IP4
Bind name resolves to this IP4 address. See \fICURLOPT_DNS_LOCAL_IP4(3)\fP
.IP CURLOPT_DNS_LOCAL_IP6
Bind name resolves to this IP6 address. See \fICURLOPT_DNS_LOCAL_IP6(3)\fP
.IP CURLOPT_DNS_SERVERS
Preferred DNS servers. See \fICURLOPT_DNS_SERVERS(3)\fP
.IP CURLOPT_DNS_SHUFFLE_ADDRESSES
Shuffle addresses before use. See \fICURLOPT_DNS_SHUFFLE_ADDRESSES(3)\fP
.IP CURLOPT_ACCEPTTIMEOUT_MS
Timeout for waiting for the server's connect back to be accepted. See \fICURLOPT_ACCEPTTIMEOUT_MS(3)\fP
.IP CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS
Timeout for happy eyeballs. See \fICURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS(3)\fP
.IP CURLOPT_UPKEEP_INTERVAL_MS
Sets the interval at which connection upkeep are performed. See
\fICURLOPT_UPKEEP_INTERVAL_MS(3)\fP
.SH SSL and SECURITY OPTIONS
.IP CURLOPT_SSLCERT
Client cert. See \fICURLOPT_SSLCERT(3)\fP
.IP CURLOPT_SSLCERT_BLOB
Client cert memory buffer. See \fICURLOPT_SSLCERT_BLOB(3)\fP
.IP CURLOPT_PROXY_SSLCERT
Proxy client cert. See \fICURLOPT_PROXY_SSLCERT(3)\fP
.IP CURLOPT_PROXY_SSLCERT_BLOB
Proxy client cert memory buffer. See \fICURLOPT_PROXY_SSLCERT_BLOB(3)\fP
.IP CURLOPT_SSLCERTTYPE
Client cert type. See \fICURLOPT_SSLCERTTYPE(3)\fP
.IP CURLOPT_PROXY_SSLCERTTYPE
Proxy client cert type. See \fICURLOPT_PROXY_SSLCERTTYPE(3)\fP
.IP CURLOPT_SSLKEY
Client key. See \fICURLOPT_SSLKEY(3)\fP
.IP CURLOPT_SSLKEY_BLOB
Client key memory buffer. See \fICURLOPT_SSLKEY_BLOB(3)\fP
.IP CURLOPT_PROXY_SSLKEY
Proxy client key. See \fICURLOPT_PROXY_SSLKEY(3)\fP
.IP CURLOPT_PROXY_SSLKEY_BLOB
Proxy client key. See \fICURLOPT_PROXY_SSLKEY_BLOB(3)\fP
.IP CURLOPT_SSLKEYTYPE
Client key type. See \fICURLOPT_SSLKEYTYPE(3)\fP
.IP CURLOPT_PROXY_SSLKEYTYPE
Proxy client key type. See \fICURLOPT_PROXY_SSLKEYTYPE(3)\fP
.IP CURLOPT_KEYPASSWD
Client key password. See \fICURLOPT_KEYPASSWD(3)\fP
.IP CURLOPT_PROXY_KEYPASSWD
Proxy client key password. See \fICURLOPT_PROXY_KEYPASSWD(3)\fP
.IP CURLOPT_SSL_EC_CURVES
Set key exchange curves. See \fICURLOPT_SSL_EC_CURVES(3)\fP
.IP CURLOPT_SSL_ENABLE_ALPN
Enable use of ALPN. See \fICURLOPT_SSL_ENABLE_ALPN(3)\fP
.IP CURLOPT_SSL_ENABLE_NPN
\fBOBSOLETE\fP Enable use of NPN. See \fICURLOPT_SSL_ENABLE_NPN(3)\fP
.IP CURLOPT_SSLENGINE
Use identifier with SSL engine. See \fICURLOPT_SSLENGINE(3)\fP
.IP CURLOPT_SSLENGINE_DEFAULT
Default SSL engine. See \fICURLOPT_SSLENGINE_DEFAULT(3)\fP
.IP CURLOPT_SSL_FALSESTART
Enable TLS False Start. See \fICURLOPT_SSL_FALSESTART(3)\fP
.IP CURLOPT_SSLVERSION
SSL version to use. See \fICURLOPT_SSLVERSION(3)\fP
.IP CURLOPT_PROXY_SSLVERSION
Proxy SSL version to use. See \fICURLOPT_PROXY_SSLVERSION(3)\fP
.IP CURLOPT_SSL_VERIFYHOST
Verify the host name in the SSL certificate. See \fICURLOPT_SSL_VERIFYHOST(3)\fP
.IP CURLOPT_DOH_SSL_VERIFYHOST
Verify the host name in the DoH (DNS-over-HTTPS) SSL certificate. See
\fICURLOPT_DOH_SSL_VERIFYHOST(3)\fP
.IP CURLOPT_PROXY_SSL_VERIFYHOST
Verify the host name in the proxy SSL certificate. See \fICURLOPT_PROXY_SSL_VERIFYHOST(3)\fP
.IP CURLOPT_SSL_VERIFYPEER
Verify the SSL certificate. See \fICURLOPT_SSL_VERIFYPEER(3)\fP
.IP CURLOPT_DOH_SSL_VERIFYPEER
Verify the DoH (DNS-over-HTTPS) SSL certificate. See
\fICURLOPT_DOH_SSL_VERIFYPEER(3)\fP
.IP CURLOPT_PROXY_SSL_VERIFYPEER
Verify the proxy SSL certificate. See \fICURLOPT_PROXY_SSL_VERIFYPEER(3)\fP
.IP CURLOPT_SSL_VERIFYSTATUS
Verify the SSL certificate's status. See \fICURLOPT_SSL_VERIFYSTATUS(3)\fP
.IP CURLOPT_DOH_SSL_VERIFYSTATUS
Verify the DoH (DNS-over-HTTPS) SSL certificate's status. See
\fICURLOPT_DOH_SSL_VERIFYSTATUS(3)\fP
.IP CURLOPT_CAINFO
CA cert bundle. See \fICURLOPT_CAINFO(3)\fP
.IP CURLOPT_CAINFO_BLOB
CA cert bundle memory buffer. See \fICURLOPT_CAINFO_BLOB(3)\fP
.IP CURLOPT_PROXY_CAINFO
Proxy CA cert bundle. See \fICURLOPT_PROXY_CAINFO(3)\fP
.IP CURLOPT_PROXY_CAINFO_BLOB
Proxy CA cert bundle memory buffer. See \fICURLOPT_PROXY_CAINFO_BLOB(3)\fP
.IP CURLOPT_ISSUERCERT
Issuer certificate. See \fICURLOPT_ISSUERCERT(3)\fP
.IP CURLOPT_ISSUERCERT_BLOB
Issuer certificate memory buffer. See \fICURLOPT_ISSUERCERT_BLOB(3)\fP
.IP CURLOPT_PROXY_ISSUERCERT
Proxy issuer certificate. See \fICURLOPT_PROXY_ISSUERCERT(3)\fP
.IP CURLOPT_PROXY_ISSUERCERT_BLOB
Proxy issuer certificate memory buffer. See \fICURLOPT_PROXY_ISSUERCERT_BLOB(3)\fP
.IP CURLOPT_CAPATH
Path to CA cert bundle. See \fICURLOPT_CAPATH(3)\fP
.IP CURLOPT_PROXY_CAPATH
Path to proxy CA cert bundle. See \fICURLOPT_PROXY_CAPATH(3)\fP
.IP CURLOPT_CRLFILE
Certificate Revocation List. See \fICURLOPT_CRLFILE(3)\fP
.IP CURLOPT_PROXY_CRLFILE
Proxy Certificate Revocation List. See \fICURLOPT_PROXY_CRLFILE(3)\fP
.IP CURLOPT_CA_CACHE_TIMEOUT
Timeout for CA cache. See \fICURLOPT_CA_CACHE_TIMEOUT(3)\fP
.IP CURLOPT_CERTINFO
Extract certificate info. See \fICURLOPT_CERTINFO(3)\fP
.IP CURLOPT_PINNEDPUBLICKEY
Set pinned SSL public key . See \fICURLOPT_PINNEDPUBLICKEY(3)\fP
.IP CURLOPT_PROXY_PINNEDPUBLICKEY
Set the proxy's pinned SSL public key. See
\fICURLOPT_PROXY_PINNEDPUBLICKEY(3)\fP
.IP CURLOPT_RANDOM_FILE
\fBOBSOLETE\fP Provide source for entropy random data.
See \fICURLOPT_RANDOM_FILE(3)\fP
.IP CURLOPT_EGDSOCKET
\fBOBSOLETE\fP Identify EGD socket for entropy. See \fICURLOPT_EGDSOCKET(3)\fP
.IP CURLOPT_SSL_CIPHER_LIST
Ciphers to use. See \fICURLOPT_SSL_CIPHER_LIST(3)\fP
.IP CURLOPT_PROXY_SSL_CIPHER_LIST
Proxy ciphers to use. See \fICURLOPT_PROXY_SSL_CIPHER_LIST(3)\fP
.IP CURLOPT_TLS13_CIPHERS
TLS 1.3 cipher suites to use. See \fICURLOPT_TLS13_CIPHERS(3)\fP
.IP CURLOPT_PROXY_TLS13_CIPHERS
Proxy TLS 1.3 cipher suites to use. See \fICURLOPT_PROXY_TLS13_CIPHERS(3)\fP
.IP CURLOPT_SSL_SESSIONID_CACHE
Disable SSL session-id cache. See \fICURLOPT_SSL_SESSIONID_CACHE(3)\fP
.IP CURLOPT_SSL_OPTIONS
Control SSL behavior. See \fICURLOPT_SSL_OPTIONS(3)\fP
.IP CURLOPT_PROXY_SSL_OPTIONS
Control proxy SSL behavior. See \fICURLOPT_PROXY_SSL_OPTIONS(3)\fP
.IP CURLOPT_KRBLEVEL
Kerberos security level. See \fICURLOPT_KRBLEVEL(3)\fP
.IP CURLOPT_GSSAPI_DELEGATION
Disable GSS-API delegation. See \fICURLOPT_GSSAPI_DELEGATION(3)\fP
.SH SSH OPTIONS
.IP CURLOPT_SSH_AUTH_TYPES
SSH authentication types. See \fICURLOPT_SSH_AUTH_TYPES(3)\fP
.IP CURLOPT_SSH_COMPRESSION
Enable SSH compression. See \fICURLOPT_SSH_COMPRESSION(3)\fP
.IP CURLOPT_SSH_HOST_PUBLIC_KEY_MD5
MD5 of host's public key. See \fICURLOPT_SSH_HOST_PUBLIC_KEY_MD5(3)\fP
.IP CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256
SHA256 of host's public key. See \fICURLOPT_SSH_HOST_PUBLIC_KEY_SHA256(3)\fP
.IP CURLOPT_SSH_PUBLIC_KEYFILE
File name of public key. See \fICURLOPT_SSH_PUBLIC_KEYFILE(3)\fP
.IP CURLOPT_SSH_PRIVATE_KEYFILE
File name of private key. See \fICURLOPT_SSH_PRIVATE_KEYFILE(3)\fP
.IP CURLOPT_SSH_KNOWNHOSTS
File name with known hosts. See \fICURLOPT_SSH_KNOWNHOSTS(3)\fP
.IP CURLOPT_SSH_KEYFUNCTION
Callback for known hosts handling. See \fICURLOPT_SSH_KEYFUNCTION(3)\fP
.IP CURLOPT_SSH_KEYDATA
Custom pointer to pass to ssh key callback. See \fICURLOPT_SSH_KEYDATA(3)\fP
.IP CURLOPT_SSH_HOSTKEYFUNCTION
Callback for checking host key handling. See \fICURLOPT_SSH_HOSTKEYFUNCTION(3)\fP
.IP CURLOPT_SSH_HOSTKEYDATA
Custom pointer to pass to ssh host key callback. See \fICURLOPT_SSH_HOSTKEYDATA(3)\fP
.SH WEBSOCKET
.IP CURLOPT_WS_OPTIONS
Set WebSocket options. See \fICURLOPT_WS_OPTIONS(3)\fP
.SH OTHER OPTIONS
.IP CURLOPT_PRIVATE
Private pointer to store. See \fICURLOPT_PRIVATE(3)\fP
.IP CURLOPT_SHARE
Share object to use. See \fICURLOPT_SHARE(3)\fP
.IP CURLOPT_NEW_FILE_PERMS
Mode for creating new remote files. See \fICURLOPT_NEW_FILE_PERMS(3)\fP
.IP CURLOPT_NEW_DIRECTORY_PERMS
Mode for creating new remote directories. See \fICURLOPT_NEW_DIRECTORY_PERMS(3)\fP
.IP CURLOPT_QUICK_EXIT
To be set by toplevel tools like "curl" to skip lengthy cleanups when they are about to call exit() anyway. See \fICURLOPT_QUICK_EXIT(3)\fP
.SH TELNET OPTIONS
.IP CURLOPT_TELNETOPTIONS
TELNET options. See \fICURLOPT_TELNETOPTIONS(3)\fP
.SH EXAMPLE
.nf
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
.fi
.SH AVAILABILITY
Always
.SH RETURN VALUE
\fICURLE_OK\fP (zero) means that the option was set properly, non-zero means an
error occurred as \fI<curl/curl.h>\fP defines. See the \fIlibcurl-errors(3)\fP
man page for the full list with descriptions.

Strings passed on to libcurl must be shorter than 8000000 bytes, otherwise
\fIcurl_easy_setopt(3)\fP returns \fBCURLE_BAD_FUNCTION_ARGUMENT\fP (added in
7.65.0).

\fBCURLE_BAD_FUNCTION_ARGUMENT\fP is returned when the argument to an option
is invalid, like perhaps out of range.

If you try to set an option that libcurl does not know about, perhaps because
the library is too old to support it or the option was removed in a recent
version, this function returns \fICURLE_UNKNOWN_OPTION\fP. If support for the
option was disabled at compile-time, it returns \fICURLE_NOT_BUILT_IN\fP.
.SH "SEE ALSO"
.BR curl_easy_cleanup (3),
.BR curl_easy_getinfo (3),
.BR curl_easy_init (3),
.BR curl_easy_option_by_id (3),
.BR curl_easy_option_by_name (3),
.BR curl_easy_option_next (3),
.BR curl_easy_reset (3),
.BR curl_multi_setopt (3)