The registry Command

	Practical Programming in Tcl & Tk, Third Edition By Brent B. Welch
	Table of Contents

	Chapter 9. Working with Files and Programs

The `registry` Command

Windows uses the registry to store various system configuration information. The Windows tool to browse and edit the registry is called regedit. Tcl provides a registry command. It is a loadable package that you must load by using:

 package require registry

The registry structure has keys, value names, and typed data. The value names are stored under a key, and each value name has data associated with it. The keys are organized into a hierarchical naming system, so another way to think of the value names is as an extra level in the hierarchy. The main point is that you need to specify both a key name and a value name in order to get something out of the registry. The key names have one of the following formats:

 \\hostname\rootname\keypath rootname\keypath rootname

The rootname is one of HKEY_LOCAL_MACHINE, HKEY_PERFORMANCE_DATA, HKEY_USERS, HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_CURRENT_CONFIG, or HKEY_DYN_DATA. Tables 9-8 and 9-9 summarize the registry command and data types:

Table 9-8. The registry command.
`registry delete` `key` `?valueName?`	Deletes the `key` and the named value, or it deletes all values under the key if `valueName` is not specified.
`registry get` `key valueName`	Returns the value associated with `valueName` under `key`.
`registry keys` `key` `?pat?`	Returns the list of keys or value names under `key` that match `pat`, which is a `string match` pattern.
`registry set` `key`	Creates `key`.
`registry set` `key valueName data` `?type?`	Creates `valueName` under `key` with value `data` of the given `type`. Types are listed in Table 9-9.
`registry type` `key valueName`	Returns the type of `valueName` under `key`.
`registry values` `key` `?pat?`	Returns the names of the values stored under `key` that match `pat`, which is a `string match` pattern.

Table 9-9. The registry data types.
`binary`	Arbitrary binary data.
`none`	Arbitrary binary data.
`expand_sz`	A string that contains references to environment variables with the `%VARNAME%` syntax.
`dword`	A 32-bit integer.
`dword_big_endian`	A 32-bit integer in the other byte order. It is represented in Tcl as a decimal string.
`link`	A symbolic link.
`multi_sz`	An array of strings, which are represented as a Tcl list.
`resource_list`	A device driver resource list.

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The registry Command

Table 9-8. The registry command.

Table 9-9. The registry data types.

The `registry` Command