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<H1><A NAME="SECTION0024200000000000000000">
22.2 <tt class="module">_winreg</tt> -
Windows registry access</A>
</H1>
<P>
<A NAME="module-winreg"></A>
<p class="availability">Availability: <span
class="platform">Windows</span>.</p>
<P>
<span class="versionnote">New in version 2.0.</span>
<P>
These functions expose the Windows registry API to Python. Instead of
using an integer as the registry handle, a handle object is used to
ensure that the handles are closed correctly, even if the programmer
neglects to explicitly close them.
<P>
This module exposes a very low-level interface to the Windows
registry; it is expected that in the future a new <code>winreg</code>
module will be created offering a higher-level interface to the
registry API.
<P>
This module offers the following functions:
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5256' xml:id='l2h-5256' class="function">CloseKey</tt></b>(</nobr></td>
<td><var>hkey</var>)</td></tr></table></dt>
<dd>
Closes a previously opened registry key.
The hkey argument specifies a previously opened key.
<P>
Note that if <var>hkey</var> is not closed using this method (or via
<tt class="method">handle.Close()</tt>), it is closed when the <var>hkey</var> object
is destroyed by Python.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5257' xml:id='l2h-5257' class="function">ConnectRegistry</tt></b>(</nobr></td>
<td><var>computer_name, key</var>)</td></tr></table></dt>
<dd>
Establishes a connection to a predefined registry handle on
another computer, and returns a <i class="dfn">handle object</i>
<P>
<var>computer_name</var> is the name of the remote computer, of the
form <code>r"\\computername"</code>. If <code>None</code>, the local computer
is used.
<P>
<var>key</var> is the predefined handle to connect to.
<P>
The return value is the handle of the opened key.
If the function fails, an <tt class="exception">EnvironmentError</tt> exception is
raised.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5258' xml:id='l2h-5258' class="function">CreateKey</tt></b>(</nobr></td>
<td><var>key, sub_key</var>)</td></tr></table></dt>
<dd>
Creates or opens the specified key, returning a <i class="dfn">handle object</i>
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that names the key this method opens
or creates.
<P>
If <var>key</var> is one of the predefined keys, <var>sub_key</var> may
be <code>None</code>. In that case, the handle returned is the same key handle
passed in to the function.
<P>
If the key already exists, this function opens the existing key
<P>
The return value is the handle of the opened key.
If the function fails, an <tt class="exception">EnvironmentError</tt> exception is
raised.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5259' xml:id='l2h-5259' class="function">DeleteKey</tt></b>(</nobr></td>
<td><var>key, sub_key</var>)</td></tr></table></dt>
<dd>
Deletes the specified key.
<P>
<var>key</var> is an already open key, or any one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that must be a subkey of the key
identified by the <var>key</var> parameter. This value must not be
<code>None</code>, and the key may not have subkeys.
<P>
<em>This method can not delete keys with subkeys.</em>
<P>
If the method succeeds, the entire key, including all of its values,
is removed. If the method fails, an <tt class="exception">EnvironmentError</tt>
exception is raised.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5260' xml:id='l2h-5260' class="function">DeleteValue</tt></b>(</nobr></td>
<td><var>key, value</var>)</td></tr></table></dt>
<dd>
Removes a named value from a registry key.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>value</var> is a string that identifies the value to remove.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5261' xml:id='l2h-5261' class="function">EnumKey</tt></b>(</nobr></td>
<td><var>key, index</var>)</td></tr></table></dt>
<dd>
Enumerates subkeys of an open registry key, returning a string.
<P>
<var>key</var> is an already open key, or any one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>index</var> is an integer that identifies the index of the key to
retrieve.
<P>
The function retrieves the name of one subkey each time it
is called. It is typically called repeatedly until an
<tt class="exception">EnvironmentError</tt> exception
is raised, indicating, no more values are available.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5262' xml:id='l2h-5262' class="function">EnumValue</tt></b>(</nobr></td>
<td><var>key, index</var>)</td></tr></table></dt>
<dd>
Enumerates values of an open registry key, returning a tuple.
<P>
<var>key</var> is an already open key, or any one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>index</var> is an integer that identifies the index of the value
to retrieve.
<P>
The function retrieves the name of one subkey each time it is
called. It is typically called repeatedly, until an
<tt class="exception">EnvironmentError</tt> exception is raised, indicating
no more values.
<P>
The result is a tuple of 3 items:
<P>
<div class="center"><table class="realtable">
<thead>
<tr>
<th class="center">Index</th>
<th class="left" >Meaning</th>
</tr>
</thead>
<tbody>
<tr><td class="center" valign="baseline"><tt class="constant">0</tt></td>
<td class="left" >A string that identifies the value name</td></tr>
<tr><td class="center" valign="baseline"><tt class="constant">1</tt></td>
<td class="left" >An object that holds the value data, and whose
type depends on the underlying registry type</td></tr>
<tr><td class="center" valign="baseline"><tt class="constant">2</tt></td>
<td class="left" >An integer that identifies the type of the value data</td></tr></tbody>
</table></div>
<P>
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5263' xml:id='l2h-5263' class="function">FlushKey</tt></b>(</nobr></td>
<td><var>key</var>)</td></tr></table></dt>
<dd>
Writes all the attributes of a key to the registry.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
It is not necessary to call RegFlushKey to change a key.
Registry changes are flushed to disk by the registry using its lazy
flusher. Registry changes are also flushed to disk at system
shutdown. Unlike <tt class="function">CloseKey()</tt>, the <tt class="function">FlushKey()</tt> method
returns only when all the data has been written to the registry.
An application should only call <tt class="function">FlushKey()</tt> if it requires absolute
certainty that registry changes are on disk.
<P>
<em>If you don't know whether a <tt class="function">FlushKey()</tt> call is required, it
probably isn't.</em>
<P>
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5264' xml:id='l2h-5264' class="function">RegLoadKey</tt></b>(</nobr></td>
<td><var>key, sub_key, file_name</var>)</td></tr></table></dt>
<dd>
Creates a subkey under the specified key and stores registration
information from a specified file into that subkey.
<P>
<var>key</var> is an already open key, or any of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that identifies the sub_key to load
<P>
<var>file_name</var> is the name of the file to load registry data from.
This file must have been created with the <tt class="function">SaveKey()</tt> function.
Under the file allocation table (FAT) file system, the filename may not
have an extension.
<P>
A call to LoadKey() fails if the calling process does not have the
<tt class="constant">SE_RESTORE_PRIVILEGE</tt> privilege. Note that privileges
are different than permissions - see the Win32 documentation for
more details.
<P>
If <var>key</var> is a handle returned by <tt class="function">ConnectRegistry()</tt>,
then the path specified in <var>fileName</var> is relative to the
remote computer.
<P>
The Win32 documentation implies <var>key</var> must be in the
<tt class="constant">HKEY_USER</tt> or <tt class="constant">HKEY_LOCAL_MACHINE</tt> tree.
This may or may not be true.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5265' xml:id='l2h-5265' class="function">OpenKey</tt></b>(</nobr></td>
<td><var>key, sub_key</var><big>[</big><var>, res<code> = 0</code></var><big>]</big><var></var><big>[</big><var>, sam<code> = <tt class="constant">KEY_READ</tt></code></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Opens the specified key, returning a <i class="dfn">handle object</i>
<P>
<var>key</var> is an already open key, or any one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that identifies the sub_key to open
<P>
<var>res</var> is a reserved integer, and must be zero. The default is zero.
<P>
<var>sam</var> is an integer that specifies an access mask that describes
the desired security access for the key. Default is <tt class="constant">KEY_READ</tt>
<P>
The result is a new handle to the specified key
<P>
If the function fails, <tt class="exception">EnvironmentError</tt> is raised.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5266' xml:id='l2h-5266' class="function">OpenKeyEx</tt></b>(</nobr></td>
<td><var></var>)</td></tr></table></dt>
<dd>
The functionality of <tt class="function">OpenKeyEx()</tt> is provided via
<tt class="function">OpenKey()</tt>, by the use of default arguments.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5267' xml:id='l2h-5267' class="function">QueryInfoKey</tt></b>(</nobr></td>
<td><var>key</var>)</td></tr></table></dt>
<dd>
Returns information about a key, as a tuple.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
The result is a tuple of 3 items:
<P>
<div class="center"><table class="realtable">
<thead>
<tr>
<th class="center">Index</th>
<th class="left" >Meaning</th>
</tr>
</thead>
<tbody>
<tr><td class="center" valign="baseline"><tt class="constant">0</tt></td>
<td class="left" >An integer giving the number of sub keys this key has.</td></tr>
<tr><td class="center" valign="baseline"><tt class="constant">1</tt></td>
<td class="left" >An integer giving the number of values this key has.</td></tr>
<tr><td class="center" valign="baseline"><tt class="constant">2</tt></td>
<td class="left" >A long integer giving when the key was last modified (if
available) as 100's of nanoseconds since Jan 1, 1600.</td></tr></tbody>
</table></div>
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5268' xml:id='l2h-5268' class="function">QueryValue</tt></b>(</nobr></td>
<td><var>key, sub_key</var>)</td></tr></table></dt>
<dd>
Retrieves the unnamed value for a key, as a string
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that holds the name of the subkey with which
the value is associated. If this parameter is <code>None</code> or empty, the
function retrieves the value set by the <tt class="function">SetValue()</tt> method
for the key identified by <var>key</var>.
<P>
Values in the registry have name, type, and data components. This
method retrieves the data for a key's first value that has a NULL name.
But the underlying API call doesn't return the type, Lame Lame Lame,
DO NOT USE THIS!!!
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5269' xml:id='l2h-5269' class="function">QueryValueEx</tt></b>(</nobr></td>
<td><var>key, value_name</var>)</td></tr></table></dt>
<dd>
Retrieves the type and data for a specified value name associated with
an open registry key.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>value_name</var> is a string indicating the value to query.
<P>
The result is a tuple of 2 items:
<P>
<div class="center"><table class="realtable">
<thead>
<tr>
<th class="center">Index</th>
<th class="left" >Meaning</th>
</tr>
</thead>
<tbody>
<tr><td class="center" valign="baseline"><tt class="constant">0</tt></td>
<td class="left" >The value of the registry item.</td></tr>
<tr><td class="center" valign="baseline"><tt class="constant">1</tt></td>
<td class="left" >An integer giving the registry type for this value.</td></tr></tbody>
</table></div>
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5270' xml:id='l2h-5270' class="function">SaveKey</tt></b>(</nobr></td>
<td><var>key, file_name</var>)</td></tr></table></dt>
<dd>
Saves the specified key, and all its subkeys to the specified file.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>file_name</var> is the name of the file to save registry data to.
This file cannot already exist. If this filename includes an extension,
it cannot be used on file allocation table (FAT) file systems by the
<tt class="method">LoadKey()</tt>, <tt class="method">ReplaceKey()</tt> or
<tt class="method">RestoreKey()</tt> methods.
<P>
If <var>key</var> represents a key on a remote computer, the path
described by <var>file_name</var> is relative to the remote computer.
The caller of this method must possess the <tt class="constant">SeBackupPrivilege</tt>
security privilege. Note that privileges are different than permissions
- see the Win32 documentation for more details.
<P>
This function passes NULL for <var>security_attributes</var> to the API.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5271' xml:id='l2h-5271' class="function">SetValue</tt></b>(</nobr></td>
<td><var>key, sub_key, type, value</var>)</td></tr></table></dt>
<dd>
Associates a value with a specified key.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that names the subkey with which the value
is associated.
<P>
<var>type</var> is an integer that specifies the type of the data.
Currently this must be <tt class="constant">REG_SZ</tt>, meaning only strings are
supported. Use the <tt class="function">SetValueEx()</tt> function for support for
other data types.
<P>
<var>value</var> is a string that specifies the new value.
<P>
If the key specified by the <var>sub_key</var> parameter does not exist,
the SetValue function creates it.
<P>
Value lengths are limited by available memory. Long values (more than
2048 bytes) should be stored as files with the filenames stored in
the configuration registry. This helps the registry perform
efficiently.
<P>
The key identified by the <var>key</var> parameter must have been
opened with <tt class="constant">KEY_SET_VALUE</tt> access.
</dl>
<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
<td><nobr><b><tt id='l2h-5272' xml:id='l2h-5272' class="function">SetValueEx</tt></b>(</nobr></td>
<td><var>key, value_name, reserved, type, value</var>)</td></tr></table></dt>
<dd>
Stores data in the value field of an open registry key.
<P>
<var>key</var> is an already open key, or one of the predefined
<tt class="constant">HKEY_*</tt> constants.
<P>
<var>sub_key</var> is a string that names the subkey with which the
value is associated.
<P>
<var>type</var> is an integer that specifies the type of the data.
This should be one of the following constants defined in this module:
<P>
<div class="center"><table class="realtable">
<thead>
<tr>
<th class="left" >Constant</th>
<th class="left" >Meaning</th>
</tr>
</thead>
<tbody>
<tr><td class="left" valign="baseline"><tt class="constant">REG_BINARY</tt></td>
<td class="left" >Binary data in any form.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_DWORD</tt></td>
<td class="left" >A 32-bit number.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_DWORD_LITTLE_ENDIAN</tt></td>
<td class="left" >A 32-bit number in little-endian format.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_DWORD_BIG_ENDIAN</tt></td>
<td class="left" >A 32-bit number in big-endian format.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_EXPAND_SZ</tt></td>
<td class="left" >Null-terminated string containing references
to environment variables ("<tt class="samp">%PATH%</tt>").</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_LINK</tt></td>
<td class="left" >A Unicode symbolic link.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_MULTI_SZ</tt></td>
<td class="left" >A sequence of null-terminated strings,
terminated by two null characters. (Python handles
this termination automatically.)</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_NONE</tt></td>
<td class="left" >No defined value type.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_RESOURCE_LIST</tt></td>
<td class="left" >A device-driver resource list.</td></tr>
<tr><td class="left" valign="baseline"><tt class="constant">REG_SZ</tt></td>
<td class="left" >A null-terminated string.</td></tr></tbody>
</table></div>
<P>
<var>reserved</var> can be anything - zero is always passed to the
API.
<P>
<var>value</var> is a string that specifies the new value.
<P>
This method can also set additional value and type information for the
specified key. The key identified by the key parameter must have been
opened with <tt class="constant">KEY_SET_VALUE</tt> access.
<P>
To open the key, use the <tt class="function">CreateKeyEx()</tt> or
<tt class="function">OpenKey()</tt> methods.
<P>
Value lengths are limited by available memory. Long values (more than
2048 bytes) should be stored as files with the filenames stored in
the configuration registry. This helps the registry perform efficiently.
</dl>
<P>
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<span class="release-info">Release 2.4.3, documentation updated on 29 March 2006.</span>
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