Reading value from an ini style file with sed/awk - bash

Question

I wrote a simple bash function which would read value from an ini file (defined by variable CONF_FILE) and output it
getConfValue() {
#getConfValue section variable
#return value of a specific variable from given section of a conf file
section=$1
var="$2"
val=$(sed -nr "/\[$section\]/,/\[/{/$var/p}" $CONF_FILE)
val=${val#$var=}
echo "$val"
}
The problem is that it does not ignore comments and runs into troubles if multiple variables within a section names share common substrings.
Example ini file:
[general]
# TEST=old
; TEST=comment
TEST=new
TESTING=this will be output too
PATH=/tmp/test
Running getConfValue general PATH would output /tmp/test as expected, but running getConfValue general TEST shows all the problems this approach has.
How to fix that?
I know there are dedicated tools like crudini or tools for python, perl and php out in the wild, but I do not want to add extra dependencies for simple config file parsing. A solution incorporating awk instead of sed would be just fine too.

Answer 1

Sticking with sed you could anchor your var search to the start of the record using ^ and end it with an equal sign:
"/\[$section\]/,/\[/{/^$var=/p}"
If you are concerned about whitespace in front of your record you could account for that:
"/\[$section\]/,/\[/{/^(\W|)$var=/p}"
That ^(\W|)$var= says "if there is whitespace at the beginning (^(\W) or nothing (|)) before your variable concatenated with an equal sign ($var=)."
If you wanted to switch over to awk you could use something like:
val=$(awk -F"=" -v section=$section -v var=$var '$1=="["section"]"{secFound=1}secFound==1 && $1==var{print $2; secFound=0}' $CONF_FILE)
That awk command splits the record by equal -F"=". Then if the first field in the record is your section ($1=="["section"]") then set variable secFound to 1. Then... if secFound is 1 and the first field is exactly equal to your var variable (secFound==1 && $1==var) then print out the second field ({print $2}) and sets secFound to 0 so we don't pick up any other Test keys.

Answer 2

I encountered this problem and came up with a solution similar to others here.
The main difference is it uses a single awk call to get a response suitable for creating an associative array of the property/value pairs for a section.
This will not ignore the commented properties. Though adding something to do that should not be to hard.
Here's a testing script demonstrating the awk and declare statements used;
#!/bin/bash
#
# Parse a INI style properties file and extract property values for a given section
#
# Author: Alan Carlyle
# License: CC0 (https://creativecommons.org/about/cclicenses/)
#
# Example Input: (example.properties)
# [SEC1]
# item1=value1
# item2="value 2"
#
# [Section 2]
# property 1="Value 1 of 'Section 2'"
# property 2='Single "quoted" value'
#
# Usage:
# $ read_props example.properties "Section 2" property\ 2
# $ Single "quoted" value
#
# Section names and properties with spaces do not need to be quoted.
# Values with spaces must be quoted. Values can use single or double quotes.
# The following characters [ = ] can not be used in names or values.
#
# If the property is not provided the the whole section is outputed.
#
propertiesFile=$1
section=$2
property=$3
# Extract the propetites for the section formated as for associtive array
sectionData="( "$(awk -F'=' -v s="$section" '/^\[/{ gsub(/[\[\]]/, "", $1); f = ($1 == s); next }
NF && f{ print "["$1"]="$2 }' $propertiesFile)" )"
# Create associtive array from extracted section data
declare +x -A "properties=$sectionData"
if [ -z "$property" ]
then
echo $sectionData
else
echo ${properties[$property]}
fi