Log cleanup automation in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of log cleanup automation?

To automatically delete or archive old log files to save disk space and keep the system organized.

beginner

In PowerShell, which cmdlet is commonly used to remove files?

The <code>Remove-Item</code> cmdlet is used to delete files or folders.

intermediate

How can you find files older than 30 days in PowerShell?

Use Get-ChildItem with Where-Object to filter files by their LastWriteTime property, like: Get-ChildItem | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-30) }.

beginner

Why is it important to test a log cleanup script before scheduling it?

To make sure it deletes only the intended files and does not remove important data by mistake.

beginner

What PowerShell feature allows you to schedule a script to run regularly?

You can use Windows Task Scheduler to run PowerShell scripts on a schedule.

Which PowerShell cmdlet deletes files?

A Set-Location

B Get-Content

C Remove-Item

D New-Item

Remove-Item deletes files or folders. The others do not delete files.

How do you select files older than 7 days in PowerShell?

A Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-7) }

B Where-Object { $_.LastWriteTime -gt (Get-Date).AddDays(-7) }

C Get-ChildItem -OlderThan 7

D Remove-Item -OlderThan 7

Files older than 7 days have LastWriteTime less than the date 7 days ago.

What is a safe first step before deleting files with a script?

A Delete all files immediately

B Run the script as administrator without testing

C Ignore file dates

D Run the script with <code>-WhatIf</code> to simulate deletion

-WhatIf shows what would happen without deleting files, helping avoid mistakes.

Which tool schedules PowerShell scripts to run automatically?

A Windows Task Scheduler

B PowerShell ISE

C Notepad

D File Explorer

Windows Task Scheduler runs scripts or programs on a set schedule.

What does Get-ChildItem do in PowerShell?

A Changes file permissions

B Lists files and folders in a directory

C Creates new files

D Deletes files

Get-ChildItem lists files and folders, useful for selecting files to delete.

Explain how to create a PowerShell script that deletes log files older than 30 days.

Think about listing, filtering, deleting, and testing steps.

Describe how to schedule a PowerShell log cleanup script to run every week.

Focus on scheduling steps using Windows tools.

Practice

1. What is the main purpose of automating log cleanup using PowerShell scripts?

easy

A. To delete old log files and free up disk space

B. To create new log files automatically

C. To rename log files for better organization

D. To compress log files for faster access

Solution

1. Step 1: Understand log cleanup goal

   The goal is to remove old log files that are no longer needed to save disk space.

2. Step 2: Identify automation benefit

   Automating this process ensures logs are cleaned regularly without manual effort.

3. Final Answer:

   To delete old log files and free up disk space -> Option A

4. Quick Check:

   Log cleanup = delete old logs [OK]

Hint: Log cleanup means removing old logs to save space [OK]

Common Mistakes:

• Confusing cleanup with creating or renaming logs
• Thinking cleanup compresses files instead of deleting
• Assuming automation creates logs automatically

2. Which PowerShell command correctly lists log files older than 30 days in the folder C:\Logs?

easy

A. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -gt (Get-Date).AddDays(30) }

B. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.CreationTime -gt (Get-Date).AddDays(-30) }

C. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-30) }

D. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.CreationTime -lt (Get-Date).AddDays(30) }

Solution

1. Step 1: Identify correct date filter

   We want files older than 30 days, so LastWriteTime should be less than (Get-Date).AddDays(-30).

2. Step 2: Check command syntax

   Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-30) } uses LastWriteTime -lt (less than) 30 days ago, correctly filtering old files.

3. Final Answer:

   Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-30) } -> Option C

4. Quick Check:

   Older than 30 days = LastWriteTime -lt (Get-Date).AddDays(-30) [OK]

Hint: Use -lt (less than) with AddDays(-30) for files older than 30 days [OK]

Common Mistakes:

• Using -gt instead of -lt for older files
• Filtering by CreationTime instead of LastWriteTime
• Using AddDays(30) instead of AddDays(-30)

3. What will be the output of this PowerShell script?

Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-7) } | Remove-Item -WhatIf

medium

A. Throws an error because Remove-Item cannot be piped

B. Lists all .log files older than 7 days and deletes them

C. Deletes all .log files regardless of age

D. Shows which .log files older than 7 days would be deleted without deleting

Solution

1. Step 1: Understand the pipeline

   The script finds .log files older than 7 days using Get-ChildItem and Where-Object.

2. Step 2: Analyze Remove-Item with -WhatIf

   -WhatIf shows what would happen without deleting files, so no files are removed.

3. Final Answer:

   Shows which .log files older than 7 days would be deleted without deleting -> Option D

4. Quick Check:

   -WhatIf shows actions without executing [OK]

Hint: Remove-Item -WhatIf previews deletion without removing files [OK]

Common Mistakes:

• Thinking files are deleted with -WhatIf
• Assuming Remove-Item cannot be piped
• Confusing filter for files newer than 7 days

4. Identify the error in this PowerShell script intended to delete log files older than 15 days:

Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -gt (Get-Date).AddDays(-15) } | Remove-Item

medium

A. The filter uses -gt instead of -lt, so it deletes newer files

B. Remove-Item cannot be used in a pipeline

C. Get-ChildItem does not support -Filter parameter

D. The script is missing the -Recurse flag

Solution

1. Step 1: Check the date comparison operator

   -gt means greater than, so it selects files newer than 15 days, opposite of intended.

2. Step 2: Confirm correct operator for old files

   To delete files older than 15 days, use -lt (less than) with AddDays(-15).

3. Final Answer:

   The filter uses -gt instead of -lt, so it deletes newer files -> Option A

4. Quick Check:

   Older files need -lt, not -gt [OK]

Hint: Use -lt for files older than a date, not -gt [OK]

Common Mistakes:

• Using -gt instead of -lt for filtering old files
• Thinking Remove-Item can't be piped
• Assuming -Filter is unsupported by Get-ChildItem

5. You want to automate deleting log files older than 10 days from C:\Logs and log the deleted filenames to deleted_logs.txt. Which script correctly does this?

hard

A. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -gt (Get-Date).AddDays(-10) } | Remove-Item; Out-File -FilePath 'deleted_logs.txt' -InputObject 'Deleted logs' -Append

B. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-10) } | ForEach-Object { Remove-Item $_.FullName; $_.FullName | Out-File -FilePath 'deleted_logs.txt' -Append }

C. Remove-Item -Path 'C:\Logs\*.log' -Recurse -Force; Get-ChildItem 'deleted_logs.txt' | Out-File -FilePath 'deleted_logs.txt' -Append

D. Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Remove-Item; Add-Content -Path 'deleted_logs.txt' -Value 'Logs deleted'

Solution

1. Step 1: Filter files older than 10 days

   Use Where-Object with LastWriteTime -lt (Get-Date).AddDays(-10) to select old logs.

2. Step 2: Remove files and log names

   ForEach-Object removes each file and appends its name to deleted_logs.txt using Out-File -Append.

3. Final Answer:

   Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-10) } | ForEach-Object { Remove-Item $_.FullName; $_.FullName | Out-File -FilePath 'deleted_logs.txt' -Append } -> Option B

4. Quick Check:

   Filter old files + remove + log names = Get-ChildItem -Path 'C:\Logs' -Filter '*.log' | Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-10) } | ForEach-Object { Remove-Item $_.FullName; $_.FullName | Out-File -FilePath 'deleted_logs.txt' -Append } [OK]

Hint: Use ForEach-Object to remove and log each file name [OK]

Common Mistakes:

• Filtering with -gt instead of -lt
• Logging only a fixed string, not filenames
• Deleting files without logging
• Using Remove-Item without filtering