Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 1 | <html><head><title>CGI Environment Variables</title></head><body><h1><img alt="" src="env_files/CGIlogo.gif"> CGI Environment Variables</h1> |
| 2 | <hr> |
| 3 | |
| 4 | <p> |
| 5 | |
| 6 | In order to pass data about the information request from the server to |
| 7 | the script, the server uses command line arguments as well as |
| 8 | environment variables. These environment variables are set when the |
| 9 | server executes the gateway program. </p><p> |
| 10 | |
| 11 | </p><hr> |
| 12 | <h2>Specification</h2> |
| 13 | |
| 14 | <p> |
| 15 | The following environment variables are not request-specific and are |
| 16 | set for all requests: </p><p> |
| 17 | |
| 18 | </p><ul> |
Denis Vlasenko | c86e052 | 2007-03-20 11:30:28 +0000 | [diff] [blame] | 19 | <li> <code>SERVER_SOFTWARE</code> <p> |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 20 | |
| 21 | The name and version of the information server software answering |
| 22 | the request (and running the gateway). Format: name/version </p><p> |
| 23 | |
| 24 | </p></li><li> <code>SERVER_NAME</code> <p> |
| 25 | The server's hostname, DNS alias, or IP address as it would appear |
| 26 | in self-referencing URLs. </p><p> |
| 27 | |
Denis Vlasenko | c86e052 | 2007-03-20 11:30:28 +0000 | [diff] [blame] | 28 | </p></li><li> <code>GATEWAY_INTERFACE</code> <p> |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 29 | The revision of the CGI specification to which this server |
| 30 | complies. Format: CGI/revision</p><p> |
| 31 | |
| 32 | </p></li></ul> |
| 33 | |
| 34 | <hr> |
| 35 | |
| 36 | The following environment variables are specific to the request being |
| 37 | fulfilled by the gateway program: <p> |
| 38 | |
| 39 | </p><ul> |
| 40 | <li> <a name="protocol"><code>SERVER_PROTOCOL</code></a> <p> |
Maninder Singh | 97c6491 | 2015-05-25 13:46:36 +0200 | [diff] [blame^] | 41 | The name and revision of the information protocol this request came |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 42 | in with. Format: protocol/revision </p><p> |
| 43 | |
| 44 | </p></li><li> <code>SERVER_PORT</code> <p> |
| 45 | The port number to which the request was sent. </p><p> |
| 46 | |
| 47 | </p></li><li> <code>REQUEST_METHOD</code> <p> |
| 48 | The method with which the request was made. For HTTP, this is |
| 49 | "GET", "HEAD", "POST", etc. </p><p> |
| 50 | |
Denis Vlasenko | c86e052 | 2007-03-20 11:30:28 +0000 | [diff] [blame] | 51 | </p></li><li> <code>PATH_INFO</code> <p> |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 52 | The extra path information, as given by the client. In other |
| 53 | words, scripts can be accessed by their virtual pathname, followed |
| 54 | by extra information at the end of this path. The extra |
| 55 | information is sent as PATH_INFO. This information should be |
| 56 | decoded by the server if it comes from a URL before it is passed |
| 57 | to the CGI script.</p><p> |
| 58 | |
| 59 | </p></li><li> <code>PATH_TRANSLATED</code> <p> |
| 60 | The server provides a translated version of PATH_INFO, which takes |
| 61 | the path and does any virtual-to-physical mapping to it. </p><p> |
| 62 | |
| 63 | </p></li><li> <code>SCRIPT_NAME</code> <p> |
| 64 | A virtual path to the script being executed, used for |
| 65 | self-referencing URLs. </p><p> |
| 66 | |
Denis Vlasenko | c86e052 | 2007-03-20 11:30:28 +0000 | [diff] [blame] | 67 | </p></li><li> <a name="query"><code>QUERY_STRING</code></a> <p> |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 68 | The information which follows the ? in the <a href="http://www.ncsa.uiuc.edu/demoweb/url-primer.html">URL</a> |
| 69 | which referenced this script. This is the query information. It |
| 70 | should not be decoded in any fashion. This variable should always |
| 71 | be set when there is query information, regardless of <a href="http://hoohoo.ncsa.uiuc.edu/cgi/cl.html">command line decoding</a>. </p><p> |
| 72 | |
| 73 | </p></li><li> <code>REMOTE_HOST</code> <p> |
| 74 | The hostname making the request. If the server does not have this |
| 75 | information, it should set REMOTE_ADDR and leave this unset.</p><p> |
| 76 | |
| 77 | </p></li><li> <code>REMOTE_ADDR</code> <p> |
| 78 | The IP address of the remote host making the request. </p><p> |
| 79 | |
| 80 | </p></li><li> <code>AUTH_TYPE</code> <p> |
| 81 | If the server supports user authentication, and the script is |
| 82 | protects, this is the protocol-specific authentication method used |
| 83 | to validate the user. </p><p> |
| 84 | |
Denis Vlasenko | c86e052 | 2007-03-20 11:30:28 +0000 | [diff] [blame] | 85 | </p></li><li> <code>REMOTE_USER</code> <p> |
Denis Vlasenko | 136f42f | 2007-02-11 14:52:07 +0000 | [diff] [blame] | 86 | If the server supports user authentication, and the script is |
| 87 | protected, this is the username they have authenticated as. </p><p> |
| 88 | </p></li><li> <code>REMOTE_IDENT</code> <p> |
| 89 | If the HTTP server supports RFC 931 identification, then this |
| 90 | variable will be set to the remote user name retrieved from the |
| 91 | server. Usage of this variable should be limited to logging only. |
| 92 | </p><p> |
| 93 | |
| 94 | </p></li><li> <a name="ct"><code>CONTENT_TYPE</code></a> <p> |
| 95 | For queries which have attached information, such as HTTP POST and |
| 96 | PUT, this is the content type of the data. </p><p> |
| 97 | |
| 98 | </p></li><li> <a name="cl"><code>CONTENT_LENGTH</code></a> <p> |
| 99 | The length of the said content as given by the client. </p><p> |
| 100 | |
| 101 | </p></li></ul> |
| 102 | |
| 103 | |
| 104 | <a name="headers"><hr></a> |
| 105 | |
| 106 | In addition to these, the header lines received from the client, if |
| 107 | any, are placed into the environment with the prefix HTTP_ followed by |
| 108 | the header name. Any - characters in the header name are changed to _ |
| 109 | characters. The server may exclude any headers which it has already |
| 110 | processed, such as Authorization, Content-type, and Content-length. If |
| 111 | necessary, the server may choose to exclude any or all of these |
| 112 | headers if including them would exceed any system environment |
| 113 | limits. <p> |
| 114 | |
| 115 | An example of this is the HTTP_ACCEPT variable which was defined in |
| 116 | CGI/1.0. Another example is the header User-Agent.</p><p> |
| 117 | |
| 118 | </p><ul> |
| 119 | <li> <code>HTTP_ACCEPT</code> <p> |
| 120 | The MIME types which the client will accept, as given by HTTP |
| 121 | headers. Other protocols may need to get this information from |
| 122 | elsewhere. Each item in this list should be separated by commas as |
| 123 | per the HTTP spec. </p><p> |
| 124 | |
| 125 | Format: type/subtype, type/subtype </p><p> |
| 126 | |
| 127 | |
| 128 | </p></li><li> <code>HTTP_USER_AGENT</code><p> |
| 129 | |
| 130 | The browser the client is using to send the request. General |
| 131 | format: <code>software/version library/version</code>.</p><p> |
| 132 | |
| 133 | </p></li></ul> |
| 134 | |
| 135 | <hr> |
| 136 | <h2>Examples</h2> |
| 137 | |
| 138 | Examples of the setting of environment variables are really much better |
| 139 | <a href="http://hoohoo.ncsa.uiuc.edu/cgi/examples.html">demonstrated</a> than explained. <p> |
| 140 | |
| 141 | </p><hr> |
| 142 | |
| 143 | <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="env_files/back.gif">Return to the |
| 144 | interface specification</a> <p> |
| 145 | |
| 146 | CGI - Common Gateway Interface |
| 147 | </p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> |
| 148 | |
Denys Vlasenko | ba2dccc | 2010-07-26 01:49:12 +0200 | [diff] [blame] | 149 | </body></html> |