As an Linux/Unix Engineer i’m spending a huge percentage in developing automatism. Sometimes you need to periodically or automated create config files. I’m using the following script create them in a cool automated way.

1. You need a perfect config file e.g. Apache vHost config file
2. All occurences of required dynamic variables are replaced with %n% where “n” is numbered streight from 0 to x. If you need the same content more than once you should us the same number again.
3. Start the templating script with each value as seperated parameter and pipe the output to the destination file

This is the Script:

#!/bin/bash
# Thomas Spycher - Zero-One - 05.11.2010
# This Script reads in the piped input and goes trough it line for line
# and replaces all occurrences of %n% where n represents an Argument
# passed to the script
 
# Read in piped input
while IFS= read -r data; do
        # Search an Replace line for line
        COUNTER=0
        for ARG in "$@"     
        do
                VARNAME="%$COUNTER%"
                data=${data//$VARNAME/$ARG}
                COUNTER=`expr $COUNTER + 1`
        done
        echo "$data"
done
exit 0

For example the creation of a simple Textfile:

Welcome to %0% which lies in %1%. 
We in %0% are speaking %2%.

and the execution of the script:

cat template.txt | ./templateScript.sh "Switzerland" "Europe" "German" > switzerland.txt