How can I write a reasonable regex to findstr for cmd?

Introduction:

The command prompt in Windows is a powerful tool that allows users to execute various commands and perform different actions. One of the most useful commands in the command prompt is the findstr command. This command is used to search for specific strings or patterns in a file or output. In this blog post, we will discuss how to use findstr to print only the UUID in Windows.

What is Regex?

Before we dive into the specifics of the findstr command, it is essential to understand what regex is. Regex, short for regular expressions, is a sequence of characters that define a search pattern. Regex is used to match and find specific patterns in text, making it a powerful tool for searching and manipulating text.

Using findstr to print only the UUID:

Now that we have a basic understanding of regex let’s explore how to use findstr to print only the UUID in Windows. The command we will be using is:

wmic csproduct get uuid | findstr /R "[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}"

This command will return an empty string if the UUID is not found. If the UUID is found, it will be printed to the console. Let’s break down the command and understand how it works.

The first part of the command, “wmic csproduct get uuid,” retrieves the UUID from the system. This command will print the UUID along with other information about the system, such as the manufacturer and model.

The second part of the command, “| findstr /R “[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5},” uses the findstr command to search for the UUID in the output of the first command. The “/R” option tells findstr to use regex to search for the pattern. The pattern “[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}-[a-zA-Z0-9]{5}” is the regex pattern we are using to match the UUID. This pattern matches any string that contains five alphanumeric characters followed by a hyphen, repeated four times.

Debugging the command:

If the previous command returns an empty string, it means that the UUID was not found. There could be several reasons for this. One possible reason is that the UUID does not match the regex pattern we are using. In this case, we need to modify the regex pattern to match the UUID correctly.

Another reason the command may not be working is that there is an issue with the findstr command. We can test this by removing the findstr command from the command and seeing if the UUID is printed to the console. If the UUID is printed without the findstr command, it means there is an issue with the findstr command, and we need to troubleshoot it further.

Conclusion:

Using findstr with regex is a powerful way to search for specific patterns in text. In this blog post, we discussed how to use findstr to print only the UUID in Windows. We also explored the basics of regex and how it is used to define search patterns. Finally, we discussed how to troubleshoot the command if it is not working correctly. With this knowledge, you can use findstr and regex to search for and manipulate text in the command prompt.

To extract the UUID from the output of the wmic command, you can use the following regular expression:

([a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12})

This regular expression will match a UUID in the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, where x is any alphanumeric character.

To use this regular expression with the findstr command, you can run the following command:

wmic csproduct get uuid | findstr /R "([a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12})"

([a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12})

wmic csproduct get uuid | findstr /R "([a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12})"