1.SH FILES 2.I ~/.curlrc 3.RS 4Default config file, see --config for details. 5.SH ENVIRONMENT 6The environment variables can be specified in lower case or upper case. The 7lower case version has precedence. http_proxy is an exception as it is only 8available in lower case. 9 10Using an environment variable to set the proxy has the same effect as using 11the --proxy option. 12 13.IP "http_proxy [protocol://]<host>[:port]" 14Sets the proxy server to use for HTTP. 15.IP "HTTPS_PROXY [protocol://]<host>[:port]" 16Sets the proxy server to use for HTTPS. 17.IP "[url-protocol]_PROXY [protocol://]<host>[:port]" 18Sets the proxy server to use for [url-protocol], where the protocol is a 19protocol that curl supports and as specified in a URL. FTP, FTPS, POP3, IMAP, 20SMTP, LDAP, etc. 21.IP "ALL_PROXY [protocol://]<host>[:port]" 22Sets the proxy server to use if no protocol-specific proxy is set. 23.IP "NO_PROXY <comma-separated list of hosts/domains>" 24list of host names that shouldn't go through any proxy. If set to an asterisk 25\&'*' only, it matches all hosts. Each name in this list is matched as either 26a domain name which contains the hostname, or the hostname itself. 27 28This environment variable disables use of the proxy even when specified with 29the --proxy option. That is 30.B NO_PROXY=direct.example.com curl -x http://proxy.example.com 31.B http://direct.example.com 32accesses the target URL directly, and 33.B NO_PROXY=direct.example.com curl -x http://proxy.example.com 34.B http://somewhere.example.com 35accesses the target URL through the proxy. 36 37The list of host names can also be include numerical IP addresses, and IPv6 38versions should then be given without enclosing brackets. 39 40IPv6 numerical addresses are compared as strings, so they will only match if 41the representations are the same: "::1" is the same as "::0:1" but they don't 42match. 43.IP "CURL_SSL_BACKEND <TLS backend>" 44If curl was built with support for "MultiSSL", meaning that it has built-in 45support for more than one TLS backend, this environment variable can be set to 46the case insensitive name of the particular backend to use when curl is 47invoked. Setting a name that isn't a built-in alternative will make curl 48stay with the default. 49 50SSL backend names (case-insensitive): bearssl, gnutls, gskit, mbedtls, 51mesalink, nss, openssl, rustls, schannel, secure-transport, wolfssl 52.IP "QLOGDIR <directory name>" 53If curl was built with HTTP/3 support, setting this environment variable to a 54local directory will make curl produce qlogs in that directory, using file 55names named after the destination connection id (in hex). Do note that these 56files can become rather large. Works with both QUIC backends. 57.IP "SSLKEYLOGFILE <file name>" 58If you set this environment variable to a file name, curl will store TLS 59secrets from its connections in that file when invoked to enable you to 60analyze the TLS traffic in real time using network analyzing tools such as 61Wireshark. This works with the following TLS backends: OpenSSL, libressl, 62BoringSSL, GnuTLS, NSS and wolfSSL. 63.SH "PROXY PROTOCOL PREFIXES" 64Since curl version 7.21.7, the proxy string may be specified with a 65protocol:// prefix to specify alternative proxy protocols. 66 67If no protocol is specified in the proxy string or if the string doesn't match 68a supported one, the proxy will be treated as an HTTP proxy. 69 70The supported proxy protocol prefixes are as follows: 71.IP "http://" 72Makes it use it as an HTTP proxy. The default if no scheme prefix is used. 73.IP "https://" 74Makes it treated as an **HTTPS** proxy. 75.IP "socks4://" 76Makes it the equivalent of --socks4 77.IP "socks4a://" 78Makes it the equivalent of --socks4a 79.IP "socks5://" 80Makes it the equivalent of --socks5 81.IP "socks5h://" 82Makes it the equivalent of --socks5-hostname 83.SH EXIT CODES 84There are a bunch of different error codes and their corresponding error 85messages that may appear under error conditions. At the time of this writing, 86the exit codes are: 87.IP 1 88Unsupported protocol. This build of curl has no support for this protocol. 89.IP 2 90Failed to initialize. 91.IP 3 92URL malformed. The syntax was not correct. 93.IP 4 94A feature or option that was needed to perform the desired request was not 95enabled or was explicitly disabled at build-time. To make curl able to do 96this, you probably need another build of libcurl! 97.IP 5 98Couldn't resolve proxy. The given proxy host could not be resolved. 99.IP 6 100Couldn't resolve host. The given remote host could not be resolved. 101.IP 7 102Failed to connect to host. 103.IP 8 104Weird server reply. The server sent data curl couldn't parse. 105.IP 9 106FTP access denied. The server denied login or denied access to the particular 107resource or directory you wanted to reach. Most often you tried to change to a 108directory that doesn't exist on the server. 109.IP 10 110FTP accept failed. While waiting for the server to connect back when an active 111FTP session is used, an error code was sent over the control connection or 112similar. 113.IP 11 114FTP weird PASS reply. Curl couldn't parse the reply sent to the PASS request. 115.IP 12 116During an active FTP session while waiting for the server to connect back to 117curl, the timeout expired. 118.IP 13 119FTP weird PASV reply, Curl couldn't parse the reply sent to the PASV request. 120.IP 14 121FTP weird 227 format. Curl couldn't parse the 227-line the server sent. 122.IP 15 123FTP can't get host. Couldn't resolve the host IP we got in the 227-line. 124.IP 16 125HTTP/2 error. A problem was detected in the HTTP2 framing layer. This is 126somewhat generic and can be one out of several problems, see the error message 127for details. 128.IP 17 129FTP couldn't set binary. Couldn't change transfer method to binary. 130.IP 18 131Partial file. Only a part of the file was transferred. 132.IP 19 133FTP couldn't download/access the given file, the RETR (or similar) command 134failed. 135.IP 21 136FTP quote error. A quote command returned error from the server. 137.IP 22 138HTTP page not retrieved. The requested url was not found or returned another 139error with the HTTP error code being 400 or above. This return code only 140appears if --fail is used. 141.IP 23 142Write error. Curl couldn't write data to a local filesystem or similar. 143.IP 25 144FTP couldn't STOR file. The server denied the STOR operation, used for FTP 145uploading. 146.IP 26 147Read error. Various reading problems. 148.IP 27 149Out of memory. A memory allocation request failed. 150.IP 28 151Operation timeout. The specified time-out period was reached according to the 152conditions. 153.IP 30 154FTP PORT failed. The PORT command failed. Not all FTP servers support the PORT 155command, try doing a transfer using PASV instead! 156.IP 31 157FTP couldn't use REST. The REST command failed. This command is used for 158resumed FTP transfers. 159.IP 33 160HTTP range error. The range "command" didn't work. 161.IP 34 162HTTP post error. Internal post-request generation error. 163.IP 35 164SSL connect error. The SSL handshaking failed. 165.IP 36 166Bad download resume. Couldn't continue an earlier aborted download. 167.IP 37 168FILE couldn't read file. Failed to open the file. Permissions? 169.IP 38 170LDAP cannot bind. LDAP bind operation failed. 171.IP 39 172LDAP search failed. 173.IP 41 174Function not found. A required LDAP function was not found. 175.IP 42 176Aborted by callback. An application told curl to abort the operation. 177.IP 43 178Internal error. A function was called with a bad parameter. 179.IP 45 180Interface error. A specified outgoing interface could not be used. 181.IP 47 182Too many redirects. When following redirects, curl hit the maximum amount. 183.IP 48 184Unknown option specified to libcurl. This indicates that you passed a weird 185option to curl that was passed on to libcurl and rejected. Read up in the 186manual! 187.IP 49 188Malformed telnet option. 189.IP 51 190The peer's SSL certificate or SSH MD5 fingerprint was not OK. 191.IP 52 192The server didn't reply anything, which here is considered an error. 193.IP 53 194SSL crypto engine not found. 195.IP 54 196Cannot set SSL crypto engine as default. 197.IP 55 198Failed sending network data. 199.IP 56 200Failure in receiving network data. 201.IP 58 202Problem with the local certificate. 203.IP 59 204Couldn't use specified SSL cipher. 205.IP 60 206Peer certificate cannot be authenticated with known CA certificates. 207.IP 61 208Unrecognized transfer encoding. 209.IP 62 210Invalid LDAP URL. 211.IP 63 212Maximum file size exceeded. 213.IP 64 214Requested FTP SSL level failed. 215.IP 65 216Sending the data requires a rewind that failed. 217.IP 66 218Failed to initialise SSL Engine. 219.IP 67 220The user name, password, or similar was not accepted and curl failed to log in. 221.IP 68 222File not found on TFTP server. 223.IP 69 224Permission problem on TFTP server. 225.IP 70 226Out of disk space on TFTP server. 227.IP 71 228Illegal TFTP operation. 229.IP 72 230Unknown TFTP transfer ID. 231.IP 73 232File already exists (TFTP). 233.IP 74 234No such user (TFTP). 235.IP 75 236Character conversion failed. 237.IP 76 238Character conversion functions required. 239.IP 77 240Problem reading the SSL CA cert (path? access rights?). 241.IP 78 242The resource referenced in the URL does not exist. 243.IP 79 244An unspecified error occurred during the SSH session. 245.IP 80 246Failed to shut down the SSL connection. 247.IP 82 248Could not load CRL file, missing or wrong format (added in 7.19.0). 249.IP 83 250Issuer check failed (added in 7.19.0). 251.IP 84 252The FTP PRET command failed. 253.IP 85 254Mismatch of RTSP CSeq numbers. 255.IP 86 256Mismatch of RTSP Session Identifiers. 257.IP 87 258Unable to parse FTP file list. 259.IP 88 260FTP chunk callback reported error. 261.IP 89 262No connection available, the session will be queued. 263.IP 90 264SSL public key does not matched pinned public key. 265.IP 91 266Invalid SSL certificate status. 267.IP 92 268Stream error in HTTP/2 framing layer. 269.IP 93 270An API function was called from inside a callback. 271.IP 94 272An authentication function returned an error. 273.IP 95 274A problem was detected in the HTTP/3 layer. This is somewhat generic and can 275be one out of several problems, see the error message for details. 276.IP 96 277QUIC connection error. This error may be caused by an SSL library error. QUIC 278is the protocol used for HTTP/3 transfers. 279.IP XX 280More error codes will appear here in future releases. The existing ones 281are meant to never change. 282.SH AUTHORS / CONTRIBUTORS 283Daniel Stenberg is the main author, but the whole list of contributors is 284found in the separate THANKS file. 285.SH WWW 286https://curl.se 287.SH "SEE ALSO" 288.BR ftp (1), 289.BR wget (1) 290