PowerShell Script to Sort Lines in a File

Use Get-Content 'input.txt' | Sort-Object | Set-Content 'output.txt' to read lines from a file, sort them alphabetically, and save the result to another file.

Examples

Inputbanana apple carrot

Outputapple banana carrot

Inputdog cat bird ant

Outputant bird cat dog

Input

Output

How to Think About It

To sort lines in a file, first read all lines into memory, then arrange them in alphabetical order using a sorting method, and finally write the sorted lines back to a file.

Algorithm

1

Read all lines from the input file.

2

Sort the lines alphabetically.

3

Write the sorted lines to the output file.

Code

powershell

Get-Content 'input.txt' | Sort-Object | Set-Content 'output.txt'
Write-Output "Lines sorted and saved to output.txt"

Output

Lines sorted and saved to output.txt

Dry Run

Let's trace sorting the lines 'banana', 'apple', 'carrot' through the code

1

Read lines

Lines read: ['banana', 'apple', 'carrot']

2

Sort lines

Sorted lines: ['apple', 'banana', 'carrot']

3

Write lines

Sorted lines saved to output.txt

Step	Lines
Read	banana, apple, carrot
Sort	apple, banana, carrot
Write	apple, banana, carrot

Why This Works

Step 1: Reading the file

The Get-Content command reads all lines from the file into an array.

Step 2: Sorting the lines

The Sort-Object command sorts the array alphabetically by default.

Step 3: Saving the sorted lines

The Set-Content command writes the sorted lines back to a file.

Alternative Approaches

Using Out-File instead of Set-Content

powershell

Get-Content 'input.txt' | Sort-Object | Out-File 'output.txt'
Write-Output "Sorted lines saved with Out-File"

Out-File adds default encoding and may add a newline at the end; Set-Content is simpler for plain text.

Sorting lines in-place

powershell

$lines = Get-Content 'input.txt'
$lines | Sort-Object | Set-Content 'input.txt'
Write-Output "File sorted in-place"

This overwrites the original file; use with caution to avoid data loss.

Complexity: O(n log n) time, O(n) space

Time Complexity

Sorting lines requires comparing them, which takes O(n log n) time where n is the number of lines.

Space Complexity

All lines are loaded into memory, so space used is proportional to the number of lines, O(n).

Which Approach is Fastest?

Using Sort-Object is efficient and built-in; sorting in-place saves disk space but risks data loss.

Approach	Time	Space	Best For
Get-Content + Sort-Object + Set-Content	O(n log n)	O(n)	Safe sorting with separate output file
Get-Content + Sort-Object + Out-File	O(n log n)	O(n)	Similar to Set-Content but with encoding control
In-place sorting with overwrite	O(n log n)	O(n)	When you want to replace original file quickly