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How to Display the Last N Lines of a File in Batch Script

Viewing the end of a file is a critical task for monitoring real-time processes. You might need to check the most recent entries in a growing log file, see the last few records in a large data set, or verify the footer of a configuration file. In the Linux world, this is the job of the tail command. While Windows Batch lacks a native tail command, this functionality can be achieved with modern tools.

This guide will show you the best and simplest method for displaying the last N lines of a file using a powerful PowerShell one-liner. For completeness, it will also explain the traditional, far more complex "pure-batch" method, highlighting why the modern approach is overwhelmingly superior for this task.

The Challenge: Why "Tailing" is Harder than "Heading"​

Reading the first N lines of a file is easy: you just read from the beginning and stop after N lines. To read the last N lines, a script can't just start reading from the end. It must first figure out where the last N lines begin, which typically requires knowing the total number of lines in the file. This makes a pure-batch solution cumbersome.

For any modern Windows system, the best solution is to call PowerShell. Its Get-Content cmdlet has a built-in -Tail parameter that does exactly what we need in a single, efficient step.

The syntax: powershell -Command "Get-Content 'filename.txt' -Tail N"

  • Get-Content: The PowerShell cmdlet for reading files.
  • -Tail N: This parameter tells it to read and display only the last N lines from the file.

This one-liner is fast, reliable, and handles all edge cases (like empty lines) correctly.

The Traditional Batch Method: Count, Calculate, and Skip​

For educational purposes, it's useful to understand how this would be done in pure batch script. The process is a complex, multi-step operation.

The logic:

  1. Count: First, get the total number of lines in the file using find /c /v "".
  2. Calculate: Subtract the number of lines you want to see (N) from the total to find out how many lines you need to skip.
  3. Skip and Print: Use a FOR /F loop with the skip=... option to read the file, ignoring all lines up to the calculated starting point.
@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION

SET "FILENAME=large_log_file.log"
SET "LINES_TO_SHOW=10"

REM Step 1: Count total lines
FOR /F %%C IN ('FIND /C /V "" ^< "%FILENAME%"') DO SET "TotalLines=%%C"

REM Step 2: Calculate lines to skip
SET /A "LinesToSkip=%TotalLines% - %LINES_TO_SHOW%"

ECHO Total Lines: %TotalLines%
ECHO Lines to Skip: %LinesToSkip%
ECHO --- Displaying last %LINES_TO_SHOW% lines ---

IF %LinesToSkip% LSS 0 SET "LinesToSkip=0"

REM Step 3: Skip and print
FOR /F "skip=%LinesToSkip% delims=" %%L IN ('FINDSTR /N "^" "%FILENAME%"') DO (
    SET "line=%%L"
    ECHO !line:*:=!
)
note

This version uses FINDSTR /N "^" to handle empty lines correctly, which adds even more complexity.* As you can see, this is far more complicated than the PowerShell equivalent.

Basic Example: Displaying the Last 5 Lines​

Let's display the end of a sample log file using both methods.

... (many lines) ...
INFO: Task completed.
WARN: High memory usage detected.
INFO: Starting cleanup process...

INFO: Cleanup finished.
@ECHO OFF
powershell -Command "Get-Content 'app_activity.log' -Tail 5"

Output:

INFO: Task completed.
WARN: High memory usage detected.
INFO: Starting cleanup process...

INFO: Cleanup finished.

Method 2: Batch Script (Complex)​

@ECHO OFF
SETLOCAL ENABLEDELAYEDEXPANSION

SET "FILENAME=app_activity.log"
SET "LINES_TO_SHOW=10"

REM Step 1: Count total lines
FOR /F %%C IN ('FIND /C /V "" ^< "%FILENAME%"') DO SET "TotalLines=%%C"

REM Step 2: Calculate lines to skip
SET /A "LinesToSkip=%TotalLines% - %LINES_TO_SHOW%"

ECHO Total Lines: %TotalLines%
ECHO Lines to Skip: %LinesToSkip%
ECHO --- Displaying last %LINES_TO_SHOW% lines ---

IF %LinesToSkip% LSS 0 SET "LinesToSkip=0"

REM Step 3: Skip and print
FOR /F "skip=%LinesToSkip% delims=" %%L IN ('FINDSTR /N "^" "%FILENAME%"') DO (
    SET "line=%%L"
    ECHO !line:*:=!
)

Output:

INFO: Task completed.
WARN: High memory usage detected.
INFO: Starting cleanup process...

INFO: Cleanup finished.

Common Pitfalls and How to Solve Them​

Problem: The File Has Fewer Lines Than Requested​

What happens if you ask for the last 100 lines of a file that only has 50?

  • PowerShell Get-Content -Tail: It will simply display the entire file (all 50 lines). No error occurs.
  • Batch FOR /F loop: The calculation for LinesToSkip will result in a negative number. The script handles this, setting the skip count to 0 and displaying the whole file.

In both cases, the behavior is graceful and generally what is desired.

Problem: Capturing the Output to a New File​

Instead of just displaying the lines, you might want to create a new file containing just the tail end of a larger file.

Solution: Use Redirection​

PowerShell (Recommended): Pipe the output to PowerShell's Set-Content cmdlet. This is the cleanest method.

powershell -Command "Get-Content 'large.log' -Tail 1000 | Set-Content 'log_summary.log'"

Batch: Wrap the entire FOR loop structure in parentheses and redirect its output.

(FOR /F ... DO (
    ...
)) > log_summary.log

Practical Example: Monitoring the End of a Log File​

This script creates a simple "monitor" that repeatedly displays the last 10 lines of a log file every 5 seconds, allowing you to watch activity in near real-time. This is a perfect use case for the tail functionality.

@ECHO OFF
SET "LOG_FILE=C:\Application\Logs\realtime_activity.log"
SET "LINES_TO_SHOW=10"

:Loop
CLS
ECHO --- Monitoring last %LINES_TO_SHOW% lines of %LOG_FILE% ---
ECHO --- Press Ctrl+C to stop ---
ECHO.

powershell -Command "Get-Content '%LOG_FILE%' -Tail %LINES_TO_SHOW%"

TIMEOUT /T 5 > NUL
GOTO :Loop

This script provides a powerful monitoring window with just a few lines of code, demonstrating the efficiency of the PowerShell method.

Conclusion​

While batch scripting doesn't have a native tail command, the functionality is readily available on all modern Windows systems through PowerShell.

  • The traditional batch method is extremely complex, slow (as it has to read the file twice), and prone to errors with edge cases like empty lines. It is not recommended for production use.
  • The PowerShell Get-Content -Tail N command is the modern, recommended best practice. It is a single, efficient, and reliable command that correctly handles all file types and is trivial to embed in any batch script.

For any task that requires reading the end of a file, leveraging the power of PowerShell is the simplest and most effective solution.

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