blob: 66a548b4656bcc510443767dafada02197b7dd78
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> |
19 | <li> <code>SERVER_SOFTWARE</code> <p> |
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 | |
28 | </p></li><li> <code>GATEWAY_INTERFACE</code> <p> |
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> |
41 | The name and revision of the information protocol this request came |
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 | |
51 | </p></li><li> <code>PATH_INFO</code> <p> |
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 | |
67 | </p></li><li> <a name="query"><code>QUERY_STRING</code></a> <p> |
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 | |
85 | </p></li><li> <code>REMOTE_USER</code> <p> |
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 | |
149 | </body></html> |
150 |