Was ECHO ON or OFF when my Windows .bat was CALLed?

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06-10-2024

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Unmasking the Echo Mystery: Was ECHO ON or OFF When My Batch File Was Called?

Have you ever found yourself staring at a Windows batch script, scratching your head over an unexpected output? Maybe the script is displaying commands instead of executing them, or worse, silently failing without any indication. The culprit might be the elusive ECHO command, and understanding its state when your batch file is called is key to solving the mystery.

Scenario:

Let's say you have a batch file named my_script.bat that looks like this:

@echo off
echo This is a test
echo This line should be executed
call another_script.bat
echo This line should be executed too

You call my_script.bat from another script or directly from the command prompt, and to your surprise, you only see the output of This is a test. Where did the other lines go?

The Problem:

The @echo off command at the beginning of the script turns off the display of commands as they are executed. While this is useful for cleaner output, it can lead to confusion if you are not aware of its effect. When call another_script.bat is executed, it inherits the ECHO OFF state from my_script.bat, effectively silencing any echo commands within another_script.bat.

The Solution:

There are a few ways to handle this situation:

• Turn ECHO ON in another_script.bat: Simply add @echo on at the beginning of another_script.bat to override the inherited state.
• Use echo with the > redirection: This will write the output to a file, regardless of the ECHO state:

  echo This line should be executed > log.txt
  

• Check the ECHO state in another_script.bat: You can use the if command to determine the current ECHO state:

  @echo off
  if %echo%==on (
      echo ECHO is ON
  ) else (
      echo ECHO is OFF
  )
  

Additional Tips:

• Use echo judiciously: Only use echo when necessary, as it can clutter your output.
• Document your scripts: Clearly mark the ECHO state at the beginning of each script for easier debugging.
• Understand the call command: The call command executes a separate batch file but returns control to the calling script after completion.

By understanding the nuances of the ECHO command and its interaction with call, you can avoid unexpected behavior in your batch scripts and ensure they run smoothly.

References:

• Microsoft Docs: ECHO
• Microsoft Docs: CALL