python: Added PDM support in scgi-wsgi{,3}.
[ashd.git] / doc / dirplex.doc
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1dirplex(1)
2==========
3
4NAME
5----
6dirplex - Physical directory handler for ashd(7)
7
8SYNOPSIS
9--------
10*dirplex* [*-hN*] [*-c* 'CONFIG'] 'DIR'
11
12DESCRIPTION
13-----------
14
15The *dirplex* handler maps URLs into physical files or directories,
16and, having found a matching file or directory, it performs various
17kinds of pattern-matching against its physical name to determine what
18handler to call in order to serve the request. The mapping procedure
19and pattern matching are described below.
20
21Having found a handler to serve a file or directory with, *dirplex*
22adds the `X-Ash-File` header to the request with a path to the
23physical file, before passing the request on to the handler.
24
25*dirplex* is a persistent handler, as defined in *ashd*(7).
26
27OPTIONS
28-------
29
30*-h*::
31
1406acb5 32 Print a brief help message to standard output and exit.
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33
34*-N*::
35
36 Do not read the global configuration file `dirplex.rc`.
37
38*-c* 'CONFIG'::
39
40 Read an extra configuration file. If 'CONFIG' contains any
41 slashes, it is opened by that exact name. Otherwise, it is
42 searched for in the same way as the global configuration file
43 (see CONFIGURATION below).
44
45URL-TO-FILE MAPPING
46-------------------
47
48Mapping URLs into physical files is an iterative procedure, each step
49looking in one single physical directory, starting with 'DIR'. For
50each step, a path element is stripped off the beginning of the rest
51string and examined, the path element being either the leading part of
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52the rest string up until (but not including) the first slash, or the
53entire rest string if it contains no slashes. If the rest string is
54empty, the directory being examined is considered the result of the
55mapping. Otherwise, any escape sequences in the path element under
56consideration are unescaped before examining it.
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b70b2d4f 58If the path element names a directory in the current directory, the
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59procedure continues in that directory, unless there is nothing left of
60the rest string, in which case *dirplex* responds with a HTTP 301
61redirect to the same URL, but ending with a slash. Otherwise, the
62remaining rest string begins with a slash, which is stripped off
63before continuing. If the path element names a file, that file is
64considered the result of the mapping (even if the rest string has not
65been exhausted yet).
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66
67If the path element does not name anything in the directory under
68consideration, but contains no dots, then the directory is searched
69for a file whose name before the first dot matches the path
70element. If there is such a file, it is considered the result of the
71mapping.
72
73If the result of the mapping procedure is a directory, it is checked
74for the presence of a filed named by the *index-file* configuration
75directive (see CONFIGURATION below). If there is such a file, it is
76considered the final result instead of the directory itself. If the
77index file name contains no dots and there is no exact match, then,
78again, the directory is searched for a file whose name before the
79first dot matches the index file name.
80
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81See also 404 RESPONSES below.
82
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83CONFIGURATION
84-------------
85
86Configuration in *dirplex* comes from several sources. When *dirplex*
87starts, unless the *-N* option is given, it tries to find a global
88configuration file named `dirplex.rc`. It looks in all directories
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89named by the *PATH* environment variable, appended with
90`../etc/ashd`. For example, then, if *PATH* is
91`/usr/local/bin:/bin:/usr/bin`, the directories `/usr/local/etc/ashd`,
92`/etc/ashd` and `/usr/etc/ashd` are searched for `dirplex.rc`, in that
93order. Only the first file found is used, should there exist several.
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94
95If the *-c* option is given to *dirplex*, it too specifies a
96configuration file to load. If the name given contains any slashes, it
97is opened by that exact name. Otherwise, it is searched for in the
98same manner as the global configuration file.
99
100In addition, all directories traversed by *dirplex* when mapping a URL
101into a physical file may contain a file called `.htrc`, which may
102specify extra configuration options for all files in and beneath that
103directory.
104
105`.htrc` files are checked periodically and reread if changed. The
106global configuration file and any file named by the *-c* option,
107however, are never reexamined.
108
109When using the configuration files for deciding what to do with a
110found file, they are examined in order of their "distance" from that
111file. `.htrc` files found in the directory or directories containing
112the file are considered "closest" to the file under consideration,
113followed by any configuration file named by the *-c* option, followed
114by the global configuration file.
115
116Each configuration file is a sequence of configuration stanzas, each
117stanza being an unindented starting line, followed by zero or more
118indented follow-up lines adding options to the stanza. The starting
119line of a stanza is referred to as a "configuration directive"
120below. Each line is a sequence of whitespace-separated words. A word
121may contain whitespace if such whitespace is escaped, either by
122enclosing the word in double quotes, or by escaping individual
123whitespace characters with a preceding backslash. Backslash quoting
124may also be used to treat double quotes or another backslash literally
125as part of the word. Empty lines are ignored, and lines whose first
126character after leading whitespace is a hash character (`#`) are
127treated as comments and ignored.
128
fda48525 129The following configuration directives are recognized:
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131*include* ['FILENAME'...]::
132
16c2bec3 133 Read the named files and act as if their contents stood in
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134 place of the *include* stanza. A 'FILENAME' may be a glob
135 pattern, in which case all matching files are used, sorted by
136 their filenames. If a 'FILENAME' is a relative path, it is
137 treated relative to the directory containing the file from
138 which the *include* stanza was read, even if the inclusion has
139 been nested. Inclusions may be nested to any level.
140
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141*index-file* ['FILENAME'...]::
142
143 The given 'FILENAMEs' are used for finding index files (see
144 URL-TO-FILE MAPPING above). Specifying *index-file* overrides
145 entirely any previous specification in a more distant
146 configuration file, rather than adding to it. Zero 'FILENAMEs'
147 may be given to turn off index file searching completely. The
148 *index-file* directive accepts no follow-up lines.
149
150*child* 'NAME'::
151
152 Declares a named, persistent request handler (see *ashd*(7)
153 for a more detailed description of persistent handlers). It
154 must contain exactly one follow-up line, *exec* 'PROGRAM'
155 ['ARGS'...], specifying the program to execute and the
156 arguments to pass it. If given in a `.htrc` file, the program
157 will be started in the same directory as the `.htrc` file
158 itself. The *child* stanza itself serves as the identity of
159 the forked process -- only one child process will be forked
160 per stanza, and if that child process exits, it will be
161 restarted the next time the stanza would be used. If a `.htrc`
162 file containing *child* stanzas is reloaded, any currently
163 running children are reused for *child* stanzas in the new
164 file with matching names (even if the *exec* line has
165 changed).
166
167*fchild* 'NAME'::
168
169 Declares a named, transient request handler (see *ashd*(7) for
16c2bec3 170 a more detailed description of transient handlers). It must
67223ca4 171 contain exactly one follow-up line, *exec* 'PROGRAM'
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172 ['ARGS'...], specifying the program to execute and the
173 arguments to pass it. In addition to the specified arguments,
174 the HTTP method, raw URL and the rest string will be appended
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175 as described in *ashd*(7). If given in a `.htrc` file, the
176 program will be started in the same directory as the `.htrc`
177 file itself.
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178
179*match* [*directory*]::
180
181 Specifies a filename pattern-matching rule. The
182 pattern-matching procedure and the follow-up lines accepted by
183 this stanza are described below, under MATCHING.
184
54490135 185*capture* 'HANDLER' ['FLAGS']::
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186
187 Only meaningful in `.htrc` files. If a *capture* directive is
188 specified, then the URL-to-file mapping procedure as described
189 above is aborted as soon as the directory containing the
190 `.htrc` file is encountered. The request is passed, with any
191 remaining rest string, to the specified 'HANDLER', which must
fda48525 192 be a named request handler specified either in the same
e7e3e593 193 `.htrc` file or elsewhere. The *capture* directive accepts no
16c2bec3 194 follow-up lines. Note that the `X-Ash-File` header is not
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195 added to requests passed via *capture* directives. If 'FLAGS'
196 contain the character `R`, this *capture* directive will be
197 ignored if it is in the root directory that *dirplex* serves.
54490135 198
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199MATCHING
200--------
201
202When a file or directory has been found by the mapping procedure (see
203URL-TO-FILE MAPPING above), the name of the physical file is examined
204to determine a request handler to pass the request to. Note that only
205the physical file name is ever considered; any logical request
206parameters such as the request URL or the rest string are entirely
207ignored.
208
209To match a file, any *match* stanzas specified by any `.htrc` file or
210in the global configuration files are searched in order of their
211"distance" (see CONFIGURATION above) from the actual file. If it is a
212directory which is being considered, only *match* stanzas with the
213*directory* parameter are considered; otherwise, if it is a file, only
214*match* stanzas without the *directory* parameter are considered.
215
216A *match* stanza must contain at least one follow-up line specifying
217match rules. All rules must match for the stanza as a whole to match.
218The following rules are recognized:
219
220*filename* 'PATTERN'...::
221
222 Matches if the name of the file under consideration matches
223 any of the 'PATTERNs'. A 'PATTERN' is an ordinary glob
224 pattern, such as `*.php`. See *fnmatch*(3) for more
225 information.
226
227*pathname* 'PATTERN'...::
228
edcd094e 229 Matches if the entire path of the file under consideration
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230 matches any of the 'PATTERNs'. A 'PATTERN' is an ordinary glob
231 pattern, except that slashes are not matched by wildcards. See
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232 *fnmatch*(3) for more information. If a *pathname* rule is
233 specified in a `.htrc` file, the path will be examined as
234 relative to the directory containing the `.htrc` file, rather
235 than to the root directory being served.
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236
237*default*::
238
239 Matches if and only if no *match* stanza without a *default*
16c2bec3 240 rule matches (in any configuration file).
e7e3e593 241
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242*local*::
243
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244 Valid only in `.htrc` files, *local* matches if and only if
245 the file under consideration resides in the same directory as
246 the containing `.htrc` file.
7711283c 247
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248In addition to the rules, a *match* stanza must contain exactly one
249follow-up line specifying the action to take if it matches. The
250following actions are recognized:
251
252*handler* 'HANDLER'::
253
254 'HANDLER' must be a named handler (see CONFIGURATION
255 above). The named handler is searched for not only in the same
256 configuration file as the *match* stanza, but in all
257 configuration files that are valid for the file under
258 consideration, in order of distance. As such, a more deeply
259 nested `.htrc` file may override the specified handler without
260 having to specify any new *match* stanzas.
261
262*fork* 'PROGRAM' ['ARGS'...]::
263
264 Run a transient handler for this file, as if it were specified
265 by a *fchild* stanza. This action exists mostly for
266 convenience.
267
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268A *match* stanza may also contain any number of the following,
269optional directives:
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270
271*set* 'HEADER' 'VALUE'::
272
273 If the *match* stanza is selected as the match for a file, the
274 named HTTP 'HEADER' in the request is set to 'VALUE' before
275 passing the request on to the specified handler.
276
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277*xset* 'HEADER' 'VALUE'::
278
fda48525 279 *xset* does exactly the same thing as *set*, except that
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280 'HEADER' is automatically prepended with the `X-Ash-`
281 prefix. The intention is only to make configuration files
282 look nicer in this very common case.
283
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284404 RESPONSES
285-------------
286
16c2bec3 287A HTTP 404 response is sent to the client if
b70b2d4f 288
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289 * The mapping procedure fails to find a matching physical file;
290 * A path element is encountered during mapping which, after URL
291 unescaping, either begins with a dot or contains slashes;
292 * The mapping procedure finds a file which is neither a directory nor
fda48525 293 a regular file (or a symbolic link to any of the same);
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294 * An empty, non-final path element is encountered during mapping; or
295 * The mapping procedure results in a file which is not matched by any
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296 *match* stanza.
297
16c2bec3 298By default, *dirplex* will send a built-in 404 response, but any
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299`.htrc` file or global configuration may define a request handler
300named `.notfound` to customize the behavior. Note that, unlike
301successful requests, such a handler will not be passed the
302`X-Ash-File` header.
303
304The built-in `.notfound` handler can also be used in *match* or
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305*capture* stanzas (for example, to restrict access to certain files or
306directories).
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307
308EXAMPLES
309--------
310
311The *sendfile*(1) program can be used to serve HTML files as follows.
312
313--------
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314fchild send
315 exec sendfile
316
e7e3e593 317match
fda48525 318 filename *.html *.htm
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319 xset content-type text/html
320 handler send
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321--------
322
323Assuming the PHP CGI interpreter is installed on the system, PHP
324scripts can be used with the following configuration, using the
325*callcgi*(1) program.
326
327--------
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328# To use plain CGI, which uses more resources per handled request,
329# but less static resources:
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330fchild php
331 exec callcgi -p php-cgi
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332
333# To use FastCGI, which keeps PHP running at all times, but uses less
334# resources per handled request:
335child php
336 exec callfcgi multifscgi 5 php-cgi
337
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338match
339 filename *.php
340 handler php
341--------
342
343If there is a directory without an index file, a file listing can be
344automatically generated by the *htls*(1) program as follows.
345
346--------
347match directory
348 default
349 fork htls
350--------
351
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352The following configuration can be placed in a `.htrc` file in order
353to dedicate the directory containing that file to some external SCGI
354script engine. Note that *callscgi*, and therefore the script engine
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355itself, is started in the same directory, so that arbitrary code
356modules or data files can be put directly in that directory and be
357easily found.
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358
359--------
360child foo
361 exec callscgi scgi-wsgi -p . foo
362
363capture foo
364--------
365
366AUTHOR
367------
368Fredrik Tolf <fredrik@dolda2000.com>
369
370SEE ALSO
371--------
372*ashd*(7)