The Windows Registry is a critical component of the Windows operating system, storing configuration settings and options. Accessing and manipulating the registry can be essential for troubleshooting, system administration, and automation tasks. One of the most powerful tools for interacting with the registry from the command line is the "reg query" command. This article will explain how to use "reg query" to access and query the Windows Registry, providing practical examples to help you understand its usage.

Examples:

1. Basic Query: To query a specific registry key, you can use the following command:

   reg query HKLM\Software\Microsoft\Windows\CurrentVersion

   This command queries the CurrentVersion key under HKEY_LOCAL_MACHINE\Software\Microsoft\Windows and lists all its subkeys and values.

2. Query a Specific Value: If you want to query a specific value within a registry key, you can specify the value name:

   reg query HKLM\Software\Microsoft\Windows\CurrentVersion /v ProgramFilesDir

   This command retrieves the ProgramFilesDir value from the CurrentVersion key.

3. Recursive Query: To perform a recursive query that lists all subkeys and values under a specified key, use the /s switch:

   reg query HKLM\Software\Microsoft\Windows\CurrentVersion /s

   This command lists all subkeys and values recursively under the CurrentVersion key.

4. Exporting Registry Keys: You can also export the results of a registry query to a file for further analysis:

   reg query HKLM\Software\Microsoft\Windows\CurrentVersion /s > C:\output.txt

   This command saves the output of the recursive query to a file named output.txt on the C: drive.

5. Filtering by Data Type: To filter the query results by data type, you can use the /t switch followed by the data type. For example, to query only REG_SZ (string) values:

   reg query HKLM\Software\Microsoft\Windows\CurrentVersion /t REG_SZ

   This command lists only the string values under the CurrentVersion key.

6. Using Environment Variables: The "reg query" command can also utilize environment variables to make the command more dynamic. For example:

   reg query %USERPROFILE%\Software\Microsoft\Windows\CurrentVersion

   This command queries the CurrentVersion key under the current user's profile.