Replace Text in a File Using a Batch Script

July 31, 2018

Yesterday, I was working at a client site. The site had a Windows server that was isolated from external internet access, and installing new software was prohibited. I was tasked with removing all the id values in YAML files, setting them to null. For instance, the input file temp.yaml looks like this:

    something
      id: 4
    something else
      id: 64
    next one
      id: 231
    another one
      id: 34

The target file (result.yaml) that I wanted would look like this:

    something
      id:
    something else
      id:
    next one
      id:
    another one
      id:

The file was large, so removing each id value manually would be time-consuming. The only tool accessible on that Windows server was the CMD command prompt. Hence, I wrote a simple batch script to complete the task. Create a file called convert.bat in a text editor with the following content:

    @echo off
    for /f "tokens=1* delims=:" %%a in (temp.yaml) do (
      if "%%b"=="" (
        echo %%a
      ) else (
        echo %%a | find " id" > null && echo %%a: || echo %%a: %%b
      )
    ) > result.yaml

You can replace the text temp.yaml and result.yaml in the script with your target input and output files, respectively. Double-click to execute the script, and you're done!

For those unfamiliar with Batch scripts, here are some basic explanations:

@echo off means to suppress the command prompt display, effectively hiding it.
The for loop has some options. The tokens= parameter specifies which numbered items to read from each line (default is 1), and delims= specifies the delimiter character (default is a space).
The %%a and %%b variables are similar to arguments in batch files.

The last line exports the result to the desired file. This simple script saves a lot of time compared to doing the work manually. :)