# mod_alias

### MODULE

mod_alias

### MODULE SUMMARY

This module creates aliases and redirections.

### DESCRIPTION

This module makes it possible to map different parts of the host file system into the document tree. The following config directives are described:

- Alias
- DirectoryIndex
- ScriptAlias

### DIRECTIVE: "Alias"

Syntax: `Alias` url-path directory-filename
Default: - None -
Module: mod_alias(3)

The Alias directive allows documents to be stored in the local file system instead of the DocumentRoot location. URLs with a path that begins with `url-path` is mapped to local files that begins with `directory-filename`, for example:

    Alias /image /ftp/pub/image

and an access to `http://your.server.org/image/foo.gif` would refer to the file `/ftp/pub/image/foo.gif`.

### DIRECTIVE: "DirectoryIndex"

Syntax: `DirectoryIndex` file file ...
Default: - None -
Module: mod_alias(3)

`DirectoryIndex` specifies a list of resources to look for if a client requests a directory using a `/` at the end of the directory name. `file` depicts the name of a file in the directory. Several files may be given, in which case the server will return the first it finds, for example:

    DirectoryIndex index.html

and access to `http://your.server.org/docs/` would return `http://your.server.org/docs/index.html` if it existed.

### DIRECTIVE: "ScriptAlias"

Syntax: `ScriptAlias` url-path directory-filename
Default: - None -
Module: mod_alias(3)

The ScriptAlias directive has the same behavior as the Alias directive, except that it also marks the target directory as containing CGI scripts. URLs with a path beginning with `url-path` are mapped to scripts beginning with `directory-filename`, for example:

    ScriptAlias /cgi-bin/ /web/cgi-bin/

and an access to `http://your.server.org/cgi-bin/foo` would cause the server to run the script `/web/cgi-bin/foo`.

### EWSAPI MODULE INTERACTION

Exports the following EWSAPI interaction data, if possible:

`{real_name,{Path,AfterPath}}`
  `Path` and `AfterPath` is as defined in httpd_util:split_path/1 with one exception - `Path` has been run through default_index/2.

Uses the following exported EWSAPI functions:

- mod_alias:default_index/2
- mod_alias:path/3
- mod_alias:real_name/3

This module furthermore exports a batch of functions to be used by other EWSAPI modules:

### EXPORTS

`default_index(ConfigDB,Path) -> NewPath`

Types:

`ConfigDB = config_db()`
`Path = NewPath = string()`

If `Path` is a directory, `default_index/2`, it starts searching for resources or files that are specified in the config directive DirectoryIndex. If an appropriate resource or file is found, it is appended to the end of `Path` and then returned. `Path` is returned unaltered, if no appropriate file is found, or if `Path` is not a directory. `config_db()` is the server config file in ETS table format as described in EWSAPI Module Programming in the Inets Users Guide..

`path(Data,ConfigDB,RequestURI) -> Path`

Types:

`Data = interaction_data()`
`ConfigDB = config_db()`
`RequestURI = Path = string()`

`path/3` returns the actual file `Path` in the `RequestURI` (See RFC 1945). If the interaction data `{real_name,{Path,AfterPath}}` has been exported by mod_alias(3); `Path` is returned. If no interaction data has been exported, ServerRoot is used to generate a file `Path`. `config_db()` and `interaction_data()` are as defined in EWSAPI Module Programming in the Inets Users Guide.

`real_name(ConfigDB,RequestURI,Aliases) -> Ret`

Types:

`ConfigDB = config_db()`
`RequestURI = string()`
`Aliases = [{FakeName,RealName}]`
`Ret = {ShortPath,Path,AfterPath}`
`ShortPath = Path = AfterPath = string()`

`real_name/3` traverses `Aliases`, typically extracted from `ConfigDB`, and matches each `FakeName` with `RequestURI`. If a match is found `FakeName` is replaced with `RealName` in the match. The resulting path is split into two parts, that is `ShortPath` and `AfterPath` as defined in httpd_util:split_path/1. `Path` is generated from `ShortPath`, that is the result from default_index/2 with `ShortPath` as an argument. `config_db()` is the server config file in ETS table format as described in EWSAPI Module Programming in the Inets User Guide..

`real_script_name(ConfigDB,RequestURI,ScriptAliases) -> Ret`

Types:

`ConfigDB = config_db()`
`RequestURI = string()`
`ScriptAliases = [{FakeName,RealName}]`
`Ret = {ShortPath,AfterPath} | not_a_script`
`ShortPath = AfterPath = string()`

`real_name/3` traverses `ScriptAliases`, typically extracted from `ConfigDB`, and matches each `FakeName` with `RequestURI`. If a match is found `FakeName` is replaced with `RealName` in the match. If the resulting match is not an executable script `not_a_script` is returned. If it is a script the resulting script path is in two parts, that is `ShortPath` and `AfterPath` as defined in httpd_util:split_script_path/1. `config_db()` is the server config file in ETS table format as described in EWSAPI Module Programming in the Inets Users Guide..

### SEE ALSO

httpd(3)

### AUTHORS

Joakim Grebenö - support@erlang.ericsson.se

inets 4.2
Copyright © 1991-2005 Ericsson AB