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Using m4 macro processor to process templates via shell scripts

I recently had to develop a bash script in order to automate the submission of a job

The job submission script could be run like this

someTextOutput | thatCommand

So 'thatCommand' can be piped input directly.


My issue was that 'someTextOutput' for me needed to be template replaced with user provided inputs. For example I wanted to do this

% aCommand var1 var2
This should replace values of tokens in a template file with var1 and var2 and the resulting output should become 'someTextOutput'

I discovered the m4 template processor tool, and here was my solution, or close to it. Cool!

#!/bin/bash
# some input handling code ...
# now send over template processed output to the target command
cat /tmp/templateFile.txt | m4 -Dvar1="$1" -Dvar2="$2" | thatCommand
I can use this in so many applications, all without having to resort to other tools/scripts when I don't need to.

Happy scripting!



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