Скачать или смотреть How to Effectively Add Items to a CSV in PowerShell Using a For Loop

Learn how to utilize PowerShell for checking server patches and exporting the results to a CSV file in an efficient manner.
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This video is based on the question https://stackoverflow.com/q/63904168/ asked by the user 'user14281970' ( https://stackoverflow.com/u/14281970/ ) and on the answer https://stackoverflow.com/a/63905146/ provided by the user 'FoxDeploy' ( https://stackoverflow.com/u/1238413/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Adding Each Item from a For Loop to a CSV File in PowerShell

Whether you're managing a large number of servers or just a few, keeping track of installed patches can be a daunting task. Often, you may need to verify whether a specific patch (identified by its KB number) is installed on each server, and if not, log the system names for review. In this guide, we will address a common problem faced by PowerShell users: how to efficiently use a loop to check installed patches and append the relevant information to a CSV file.

The Challenge

As highlighted in the query, the initial attempt at the code does not successfully append the server names to a CSV file. The user is trying to use a forEach loop along with the Export-Csv cmdlet, but it appears that some critical details were missing. Before we get into the solution, let's explore why the original code might be failing.

Identifying the Problems in the Initial Code

Undefined Variables: The script did not define the values for @ sys.csv and $kb_number, which could lead to errors or blank outputs.

Export-Csv Usage: The Export-Csv cmdlet was being invoked without providing a specific object to export. This means nothing would actually be written to the CSV.

Creating New File on Each Iteration: A new CSV file creation within the loop meant that previous data was lost with each iteration.

Using Old DOS Commands: The use of wmic commands could complicate the process when native PowerShell commands can be employed instead, simplifying the overall script.

A Working Solution

To properly check for the patch installations and export the desired information to a CSV, follow these steps:

Step 1: Set Up Your Environment

Before you begin, ensure you have a list of computer names you wish to query. Save it as a text file, such as ComputerList.txt. You should also know the KB number of the patch you're checking.

Step 2: Modify Your Script

Below is a restructured script that properly checks for the patch and appends computer names to a CSV, if they do not have the patch installed.

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Explanation of the Code

File Handling: We check if the CSV file exists. If it doesn’t, we create it with headers.

Loop & Query: For each computer, we utilize Get-CimInstance to check if the patch is installed. If it isn’t, we log that computer’s name to the CSV.

Error Handling: The try-catch block ensures that you are alerted if any system does not respond or another error occurs.

General Suggestions for PowerShell Scripting

Use ForEach Over ForEach-Object: For easier debugging and readability, prefer ForEach loop instead of ForEach-Object.

Utilize PowerShell Native Commands: To ease the coding process and improve performance, stick to PowerShell cmdlets like Get-CimInstance rather than resorting to DOS commands.

Conclusion

By adjusting your approach to using PowerShell with the proper handling of CSV exports, you can efficiently manage and log your server patch statuses. This revised structure keeps your data organized, allowing for easy monitoring and management of your systems.

Now you're on your way to mastering patch management with PowerShell! Happy scripting!