Log cleanup automation in PowerShell - Mini Project: Build & Apply

Log cleanup automation

📖 Scenario: You are managing a server that generates many log files daily. To save disk space, you want to automatically delete old log files that are no longer needed.

🎯 Goal: Create a PowerShell script that deletes log files older than a certain number of days from a specific folder.

📋 What You'll Learn

Create a variable with a list of log files in a folder

Create a variable for the age limit in days

Use a loop to find and delete files older than the age limit

Print the names of deleted files

💡 Why This Matters

🌍 Real World

Automating log cleanup helps keep servers running smoothly by freeing disk space and reducing manual work.

💼 Career

System administrators and DevOps engineers often write scripts like this to maintain healthy server environments.

1

Get the list of log files

Create a variable called logFiles that stores all files with the extension .log from the folder C:\Logs using Get-ChildItem.

PowerShell

# Your code here

Hint

Use Get-ChildItem with -Path and -Filter to get log files.

2

Set the age limit for deletion

Create a variable called daysLimit and set it to 30 to represent the number of days after which log files should be deleted.

PowerShell

$logFiles = Get-ChildItem -Path 'C:\Logs' -Filter '*.log'
# Your code here

Hint

Just assign the number 30 to daysLimit.

3

Delete old log files

Use a foreach loop with the variable file to go through logFiles. Inside the loop, check if file.LastWriteTime is older than (Get-Date).AddDays(-daysLimit). If yes, delete the file using Remove-Item.

PowerShell

$logFiles = Get-ChildItem -Path 'C:\Logs' -Filter '*.log'
$daysLimit = 30
# Your code here

Hint

Use foreach to loop. Use if to compare dates. Use Remove-Item to delete.

4

Print deleted file names

Modify the loop to print the name of each deleted file using Write-Output right after deleting it. Use $file.Name to get the file name.

PowerShell

$logFiles = Get-ChildItem -Path 'C:\Logs' -Filter '*.log'
$daysLimit = 30
foreach ($file in $logFiles) {
    if ($file.LastWriteTime -lt (Get-Date).AddDays(-$daysLimit)) {
        Remove-Item $file.FullName
        # Your code here
    }
}

Hint

Use Write-Output to print the deleted file name inside the if block.

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