Groovy 2 Cookbook

Using Groovy as a command-line text file editor

The groovy command, which we introduced in the Executing Groovy code from the command line recipe, can also be used as a stream editor or text file filter. In this recipe, we will cover the -i, -n, and -p parameters that can be used to leverage file editing and processing functionality.

How to do it...

Assume that you have a file, data.txt, which contains five lines with numbers from 1 to 5:

1. To multiply each number by 2, you can use the following command:

   groovy -n -e "println line.toLong() * 2" data.txt
   

2. We can even omit the println method call if we pass additional the -p parameter to the command:

   groovy -n -p -e "line.toLong() * 2" data.txt
   

3. In both cases, Groovy will print the following output: