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Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
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Fri Apr 24 18:33:46 2009 UTC (15 years, 1 month ago) by niro
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-updated to busybox-1.13.4
1 | <html><head><title>CGI Script output</title></head><body><h1><img alt="" src="out_files/CGIlogo.gif"> CGI Script Output</h1> |
2 | <hr> |
3 | |
4 | <h2>Script output</h2> |
5 | |
6 | The script sends its output to stdout. This output can either be a |
7 | document generated by the script, or instructions to the server for |
8 | retrieving the desired output. <p> |
9 | </p><hr> |
10 | |
11 | <h2>Script naming conventions</h2> |
12 | |
13 | Normally, scripts produce output which is interpreted and sent back to |
14 | the client. An advantage of this is that the scripts do not need to |
15 | send a full HTTP/1.0 header for every request. <p> |
16 | <a name="nph"> |
17 | Some scripts may want to avoid the extra overhead of the server |
18 | parsing their output, and talk directly to the client. In order to |
19 | distinguish these scripts from the other scripts, CGI requires that |
20 | the script name begins with nph- if a script does not want the server |
21 | to parse its header. In this case, it is the script's responsibility |
22 | to return a valid HTTP/1.0 (or HTTP/0.9) response to the client. </a></p><p> |
23 | |
24 | </p><hr> |
25 | <h2><a name="nph">Parsed headers</a></h2> |
26 | |
27 | <a name="nph">The output of scripts begins with a small header. This header consists |
28 | of text lines, in the same format as an </a><a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/Object_Headers.html"> |
29 | HTTP header</a>, terminated by a blank line (a line with only a |
30 | linefeed or CR/LF). <p> |
31 | |
32 | Any headers which are not server directives are sent directly back to |
33 | the client. Currently, this specification defines three server |
34 | directives:</p><p> |
35 | |
36 | </p><ul> |
37 | <li> <code>Content-type</code> <p> |
38 | |
39 | This is the MIME type of the document you are returning. </p><p> |
40 | |
41 | </p></li><li> <code>Location</code> <p> |
42 | |
43 | This is used to specify to the server that you are returning a |
44 | reference to a document rather than an actual document. </p><p> |
45 | |
46 | If the argument to this is a URL, the server will issue a redirect |
47 | to the client. </p><p> |
48 | |
49 | If the argument to this is a virtual path, the server will |
50 | retrieve the document specified as if the client had requested |
51 | that document originally. ? directives will work in here, but # |
52 | directives must be redirected back to the client.</p><p> |
53 | |
54 | |
55 | </p></li><li> <a name="status"><code>Status</code></a><p> |
56 | |
57 | This is used to give the server an HTTP/1.0 <a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/HTRESP.html">status |
58 | line</a> to send to the client. The format is <code>nnn xxxxx</code>, |
59 | where <code>nnn</code> is the 3-digit status code, and |
60 | <code>xxxxx</code> is the reason string, such as "Forbidden".</p><p> |
61 | |
62 | </p></li></ul> |
63 | |
64 | <hr> |
65 | <h2>Examples</h2> |
66 | |
67 | Let's say I have a fromgratz to HTML converter. When my converter is |
68 | finished with its work, it will output the following on stdout (note |
69 | that the lines beginning and ending with --- are just for illustration |
70 | and would not be output): <p> |
71 | |
72 | </p><pre>--- start of output --- |
73 | Content-type: text/html |
74 | |
75 | --- end of output --- |
76 | </pre> |
77 | |
78 | Note the blank line after Content-type. <p> |
79 | |
80 | Now, let's say I have a script which, in certain instances, wants to |
81 | return the document <code>/path/doc.txt</code> from this server just |
82 | as if the user had actually requested |
83 | <code>http://server:port/path/doc.txt</code> to begin with. In this |
84 | case, the script would output: </p><p> |
85 | </p><pre>--- start of output --- |
86 | Location: /path/doc.txt |
87 | |
88 | --- end of output --- |
89 | </pre> |
90 | |
91 | The server would then perform the request and send it to the client. |
92 | <p> |
93 | |
94 | Let's say that I have a script which wants to reference our gopher |
95 | server. In this case, if the script wanted to refer the user to |
96 | <code>gopher://gopher.ncsa.uiuc.edu/</code>, it would output: </p><p> |
97 | |
98 | </p><pre>--- start of output --- |
99 | Location: gopher://gopher.ncsa.uiuc.edu/ |
100 | |
101 | --- end of output --- |
102 | </pre> |
103 | |
104 | Finally, I have a script which wants to talk to the client directly. |
105 | In this case, if the script is referenced with <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#protocol"><code>SERVER_PROTOCOL</code></a> of HTTP/1.0, |
106 | the script would output the following HTTP/1.0 response: <p> |
107 | |
108 | </p><pre>--- start of output --- |
109 | HTTP/1.0 200 OK |
110 | Server: NCSA/1.0a6 |
111 | Content-type: text/plain |
112 | |
113 | This is a plaintext document generated on the fly just for you. |
114 | |
115 | --- end of output --- |
116 | </pre> |
117 | |
118 | |
119 | <hr> |
120 | |
121 | <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="out_files/back.gif">Return to the |
122 | interface specification</a> <p> |
123 | |
124 | CGI - Common Gateway Interface |
125 | </p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> |
126 | </body></html> |