Apache HTTP Server Version 2.0

.htaccess files provide a way to make configuration
changes on a per-directory basis.
| Related Modules | Related Directives | 
|---|---|
.htaccess files (or "distributed configuration files")
    provide a way to make configuration changes on a per-directory basis. A
    file, containing one or more configuration directives, is placed in a
    particular document directory, and the directives apply to that
    directory, and all subdirectories thereof.
If you want to call your .htaccess file something
      else, you can change the name of the file using the AccessFileName directive. For example,
      if you would rather call the file .config then you
      can put the following in your server configuration file:
        AccessFileName .config
      
In general, .htaccess files use the same syntax as
    the main configuration
    files.  What you can put in these files is determined by the
    AllowOverride directive. This
    directive specifies, in categories, what directives will be
    honored if they are found in a .htaccess file. If a
    directive is permitted in a .htaccess file, the
    documentation for that directive will contain an Override section,
    specifying what value must be in AllowOverride in order for that
    directive to be permitted.
For example, if you look at the documentation for the AddDefaultCharset
    directive, you will find that it is permitted in .htaccess
    files. (See the Context line in the directive summary.) The Override line reads
    FileInfo. Thus, you must have at least
    AllowOverride FileInfo in order for this directive to be
    honored in .htaccess files.
If you are unsure whether a particular directive is permitted in a
    .htaccess file, look at the documentation for that
    directive, and check the Context line for ".htaccess".
In general, you should never use .htaccess files unless
    you don't have access to the main server configuration file. There is,
    for example, a prevailing misconception that user authentication should
    always be done in .htaccess files. This is simply not the
    case. You can put user authentication configurations in the main server
    configuration, and this is, in fact, the preferred way to do
    things.
.htaccess files should be used in a case where the
    content providers need to make configuration changes to the server on a
    per-directory basis, but do not have root access on the server system.
    In the event that the server administrator is not willing to make
    frequent configuration changes, it might be desirable to permit
    individual users to make these changes in .htaccess files
    for themselves. This is particularly true, for example, in cases where
    ISPs are hosting multiple user sites on a single machine, and want
    their users to be able to alter their configuration.
However, in general, use of .htaccess files should be
    avoided when possible. Any configuration that you would consider
    putting in a .htaccess file, can just as effectively be
    made in a <Directory> section in your main server 
    configuration file.
There are two main reasons to avoid the use of
    .htaccess files.
The first of these is performance. When AllowOverride
    is set to allow the use of .htaccess files, Apache will
    look in every directory for .htaccess files. Thus,
    permitting .htaccess files causes a performance hit,
    whether or not you actually even use them! Also, the
    .htaccess file is loaded every time a document is
    requested.
Further note that Apache must look for .htaccess files
    in all higher-level directories, in order to have a full complement of
    directives that it must apply. (See section on how
    directives are applied.) Thus, if a file is requested out of a
    directory /www/htdocs/example, Apache must look for the
    following files:
      /.htaccess
      /www/.htaccess
      /www/htdocs/.htaccess
      /www/htdocs/example/.htaccess
    
And so, for each file access out of that directory, there are 4
    additional file-system accesses, even if none of those files are
    present. (Note that this would only be the case if
    .htaccess files were enabled for /, which
    is not usually the case.)
The second consideration is one of security. You are permitting
    users to modify server configuration, which may result in changes over
    which you have no control. Carefully consider whether you want to give
    your users this privilege. Note also that giving users less
    privileges than they need will lead to additional technical support
    requests. Make sure you clearly tell your users what level of
    privileges you have given them. Specifying exactly what you have set
    AllowOverride to, and pointing them
    to the relevant documentation, will save yourself a lot of confusion
    later.
Note that it is completely equivalent to put a .htaccess
    file in a directory /www/htdocs/example containing a
    directive, and to put that same directive in a Directory section
    <Directory /www/htdocs/example> in your main server
    configuration:
.htaccess file in /www/htdocs/example:
/www/htdocs/example
        AddType text/example .exm
    
httpd.conf
    file
      <Directory /www/htdocs/example>
      
        AddType text/example .exm
      
      </Directory>
    
However, putting this configuration in your server configuration file will result in less of a performance hit, as the configuration is loaded once when Apache starts, rather than every time a file is requested.
The use of .htaccess files can be disabled completely
    by setting the AllowOverride
    directive to none:
      AllowOverride None
    
The configuration directives found in a .htaccess file
    are applied to the directory in which the .htaccess file
    is found, and to all subdirectories thereof. However, it is important
    to also remember that there may have been .htaccess files
    in directories higher up. Directives are applied in the order that they
    are found. Therefore, a .htaccess file in a particular
    directory may override directives found in .htaccess files
    found higher up in the directory tree. And those, in turn, may have
    overridden directives found yet higher up, or in the main server
    configuration file itself.
Example:
In the directory /www/htdocs/example1 we have a
    .htaccess file containing the following:
       Options +ExecCGI
    
(Note: you must have "AllowOverride Options" in effect
    to permit the use of the "Options" directive in
    .htaccess files.)
In the directory /www/htdocs/example1/example2 we have
    a .htaccess file containing:
       Options Includes
    
Because of this second .htaccess file, in the directory
    /www/htdocs/example1/example2, CGI execution is not
    permitted, as only Options Includes is in effect, which
    completely overrides any earlier setting that may have been in
    place.
As discussed in the documentation on Configuration Sections,
    .htaccess files can override the <Directory> sections for
    the corresponding directory, but will be overriden by other types
    of configuration sections from the main configuration files.  This
    fact can be used to enforce certain configurations, even in the
    presence of a liberal AllowOverride setting.  For example, to
    prevent script execution while allowing anything else to be set in
    .htaccess you can use:
<Directory />
Allowoverride All
</Directory>
<Location />
Options +IncludesNoExec -ExecCGI
</Location>
    
If you jumped directly to this part of the document to find out how
    to do authentication, it is important to note one thing. There is a
    common misconception that you are required to use
    .htaccess files in order to implement password
    authentication. This is not the case. Putting authentication directives
    in a <Directory>
    section, in your main server configuration file, is the preferred way
    to implement this, and .htaccess files should be used only
    if you don't have access to the main server configuration file. See above for a discussion of when you should and should
    not use .htaccess files.
Having said that, if you still think you need to use a
    .htaccess file, you may find that a configuration such as
    what follows may work for you.
You must have "AllowOverride AuthConfig" in effect for
    these directives to be honored.
.htaccess file contents:
      AuthType Basic
      AuthName "Password Required"
      AuthUserFile /www/passwords/password.file
      AuthGroupFile /www/passwords/group.file
      Require Group admins
    
Note that AllowOverride AuthConfig must be in effect
    for these directives to have any effect.
Please see the authentication tutorial for a more complete discussion of authentication and authorization.
Another common use of .htaccess files is to enable
    Server Side Includes for a particular directory. This may be done with
    the following configuration directives, placed in a
    .htaccess file in the desired directory:
       Options +Includes
       AddType text/html shtml
       AddHandler server-parsed shtml
    
Note that AllowOverride Options and AllowOverride
    FileInfo must both be in effect for these directives to have any
    effect.
Please see the SSI tutorial for a more complete discussion of server-side includes.
Finally, you may wish to use a .htaccess file to permit
    the execution of CGI programs in a particular directory. This may be
    implemented with the following configuration:
       Options +ExecCGI
       AddHandler cgi-script cgi pl
    
Alternately, if you wish to have all files in the given directory be considered to be CGI programs, this may be done with the following configuration:
       Options +ExecCGI
       SetHandler cgi-script
    
Note that AllowOverride Options and AllowOverride
    FileInfo must both be in effect for these directives to have any
    effect.
Please see the CGI tutorial for a more complete discussion of CGI programming and configuration.
When you put configuration directives in a .htaccess
    file, and you don't get the desired effect, there are a number of
    things that may be going wrong.
Most commonly, the problem is that AllowOverride is not
    set such that your configuration directives are being honored. Make
    sure that you don't have a AllowOverride None in effect
    for the file scope in question. A good test for this is to put garbage
    in your .htaccess file and reload. If a server error is
    not generated, then you almost certainly have AllowOverride
    None in effect.
If, on the other hand, you are getting server errors when trying to
    access documents, check your Apache error log. It will likely tell you
    that the directive used in your .htaccess file is not
    permitted. Alternately, it may tell you that you had a syntax error,
    which you will then need to fix.