bash script to generate config or property file from a template file containing variables | MyThinkPond

Sometimes we have configuration or properties file (as templates) such as httpd.conf or server.conf where we want to dynamically replace $variables with values before writing the output to a new file.


# httpd.conf.tmpl

    SetHandler server-status
    Order deny,allow
    Deny from all
    Allow from $MONITOR_IP

We want to develop an install script in Bash such that it reads the httpd.conf.tmpl and replaces the $STATUS_URI and $MONITOR_IP with appropriate values (either passed in as script arguments or coded in the bash script) and then write out the resulting output to a new file such as /tmp/httpd.conf

Here is such as script:

#!/usr/bin/env bash

# Define the variables with values you want replaced
# This could also be read in via bash arguments. 
# Google "bash getopts" for more information

# render a template configuration file
# expand variables + preserve formatting
# user="Venkatt"
# referenced inside the template.txt as $user
# render_template /path/to/template.txt > path/to/configuration_file
function render_template() {
  eval "echo \"$(cat $1)\""

function generate_httpd_conf {
  echo "#### Creating /tmp/httpd.conf from template ./httpd.conf.tmpl"
  render_template httpd.conf.tmpl > /tmp/httpd.conf

Generated output:

    SetHandler server-status
    Order deny,allow
    Deny from all
    Allow from

This can be a useful method to generate .conf .prop (configuration or properties) files.


And now for today’s inspirational quote:

Let us sacrifice our today so that our children can have a better tomorrow. - [Abdul Kalam]( - 11th President of India from 2002 to 2007 - Chief 'Rocket' Scientist born from a poor family with humble beginnings. - Lived as a "Man of simplicity"
Venkatt Guhesan avatar
About Venkatt Guhesan
Enterprise Software Architect currently working at DataDirect Networks developing a highly scalable monitoring solution called DDN Insight. My passions include all things Open Source including Linux (CentOS, Red Hat, Gentoo, Open Stack, Docker & Ubuntu), embedded ARM processors and microcontrollers (Arduino, UDOO, Cubieboard, BeagleBoard, OnionIO, TI's Zigbee). Coming from an Electrical and Computer Engineering background, working in developing and designing enterprise - distributed, highly scalable software requires a unique set of software skills with a good understanding of the hardware. This makes his work challenging and interesting. In his free time, he spends his time with his family and two children. He also enjoys researching on topics including - world ancient history and yoga. Visit the 'About' section for more details.
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