Parsing .ini file in bash - bash

Question

I have a below properties file and would like to parse it as mentioned below. Please help in doing this.
.ini file which I created :
[Machine1]
app=version1
[Machine2]
app=version1
app=version2
[Machine3]
app=version1
app=version3
I am looking for a solution in which ini file should be parsed like
[Machine1]app = version1
[Machine2]app = version1
[Machine2]app = version2
[Machine3]app = version1
[Machine3]app = version3
Thanks.

Answer 1

Try:
$ awk '/\[/{prefix=$0; next} $1{print prefix $0}' file.ini
[Machine1]app=version1
[Machine2]app=version1
[Machine2]app=version2
[Machine3]app=version1
[Machine3]app=version3
How it works
/\[/{prefix=$0; next}
If any line begins with [, we save the line in the variable prefix and then we skip the rest of the commands and jump to the next line.
$1{print prefix $0}
If the current line is not empty, we print the prefix followed by the current line.
Adding spaces
To add spaces around any occurrence of =:
$ awk -F= '/\[/{prefix=$0; next} $1{$1=$1; print prefix $0}' OFS=' = ' file.ini
[Machine1]app = version1
[Machine2]app = version1
[Machine2]app = version2
[Machine3]app = version1
[Machine3]app = version3
This works by using = as the field separator on input and = as the field separator on output.

Answer 2

I love John1024's answer. I was looking for exactly that. I have created a bash function that allows me to lookup sections or specific keys based on his idea:
function iniget() {
if [[ $# -lt 2 || ! -f $1 ]]; then
echo "usage: iniget <file> [--list|<section> [key]]"
return 1
fi
local inifile=$1
if [ "$2" == "--list" ]; then
for section in $(cat $inifile | grep "\[" | sed -e "s#\[##g" | sed -e "s#\]##g"); do
echo $section
done
return 0
fi
local section=$2
local key
[ $# -eq 3 ] && key=$3
# https://stackoverflow.com/questions/49399984/parsing-ini-file-in-bash
# This awk line turns ini sections => [section-name]key=value
local lines=$(awk '/\[/{prefix=$0; next} $1{print prefix $0}' $inifile)
for line in $lines; do
if [[ "$line" = \[$section\]* ]]; then
local keyval=$(echo $line | sed -e "s/^\[$section\]//")
if [[ -z "$key" ]]; then
echo $keyval
else
if [[ "$keyval" = $key=* ]]; then
echo $(echo $keyval | sed -e "s/^$key=//")
fi
fi
fi
done
}
So given this as file.ini
[Machine1]
app=version1
[Machine2]
app=version1
app=version2
[Machine3]
app=version1
app=version3
then the following results are produced
$ iniget file.ini --list
Machine1
Machine2
Machine3
$ iniget file.ini Machine3
app=version1
app=version3
$ iniget file.ini Machine1 app
version1
$ iniget file.ini Machine2 app
version2
version3
Again, thanks to #John1024 for his answer, I was pulling my hair out trying to create a simple bash ini parser that supported sections.
Tested on Mac using GNU bash, version 5.0.0(1)-release (x86_64-apple-darwin18.2.0)

Answer 3

You can try using awk:
awk '/\[[^]]*\]/{ # Match pattern like [...]
a=$1;next # store the pattern in a
}
NF{ # Match non empty line
gsub("=", " = ") # Add space around the = character
print a $0 # print the line
}' file

Answer 4

Excellent answers here. I made some modifications to #davfive's function to fit it better to my use case. This version is largely the same except it allows for whitespace before and after = characters, and allows values to have spaces in them.
# Get values from a .ini file
function iniget() {
if [[ $# -lt 2 || ! -f $1 ]]; then
echo "usage: iniget <file> [--list|<section> [key]]"
return 1
fi
local inifile=$1
if [ "$2" == "--list" ]; then
for section in $(cat $inifile | grep "^\\s*\[" | sed -e "s#\[##g" | sed -e "s#\]##g"); do
echo $section
done
return 0
fi
local section=$2
local key
[ $# -eq 3 ] && key=$3
# This awk line turns ini sections => [section-name]key=value
local lines=$(awk '/\[/{prefix=$0; next} $1{print prefix $0}' $inifile)
lines=$(echo "$lines" | sed -e 's/[[:blank:]]*=[[:blank:]]*/=/g')
while read -r line ; do
if [[ "$line" = \[$section\]* ]]; then
local keyval=$(echo "$line" | sed -e "s/^\[$section\]//")
if [[ -z "$key" ]]; then
echo $keyval
else
if [[ "$keyval" = $key=* ]]; then
echo $(echo $keyval | sed -e "s/^$key=//")
fi
fi
fi
done <<<"$lines"
}

Answer 5

For taking disparate sectional and tacking the section name (including 'no-section'/Default together) to each of its related keyword (along with = and its keyvalue), this one-liner AWK will do the trick coupled with a few clean-up regex.
ini_buffer="$(echo "$raw_buffer" | awk '/^\[.*\]$/{obj=$0}/=/{print obj $0}')"
Will take your lines and output them like you wanted:
+++ awk '/^\[.*\]$/{obj=$0}/=/{print obj $0}'
++ ini_buffer='[Machine1]app=version1
[Machine2]app=version1
[Machine2]app=version2
[Machine3]app=version1
[Machine3]app=version3'
A complete solution to the INI-format File
As Clonato, INI-format expert said that for the latest INI version 1.4 (2009-10-23), there are several other tricky aspects to the INI file:
character set constraint for section name
character set constraint for keyword
And lastly is for the keyvalue to be able to handle pretty much anthing that is not used in the section and keyword name; that includes nesting of quotes inside a pair of same single/double-quote.
Except for the nesting of quotes, a INI-format Github complete solution to parsing INI-format file with default section:
# syntax: ini_file_read <raw_buffer>
# outputs: formatted bracket-nested "[section]keyword=keyvalue"
ini_file_read()
{
local ini_buffer raw_buffer hidden_default
raw_buffer="$1"
# somebody has to remove the 'inline' comment
# there is a most complex SED solution to nested
# quotes inline comment coming ... TBA
raw_buffer="$(echo "$raw_buffer" | sed '
s|[[:blank:]]*//.*||; # remove //comments
s|[[:blank:]]*#.*||; # remove #comments
t prune
b
:prune
/./!d; # remove empty lines, but only those that
# become empty as a result of comment stripping'
)"
# awk does the removal of leading and trailing spaces
ini_buffer="$(echo "$raw_buffer" | awk '/^\[.*\]$/{obj=$0}/=/{print obj $0}')" # original
ini_buffer="$(echo "$ini_buffer" | sed 's/^\s*\[\s*/\[/')"
ini_buffer="$(echo "$ini_buffer" | sed 's/\s*\]\s*/\]/')"
# finds all 'no-section' and inserts '[Default]'
hidden_default="$(echo "$ini_buffer" \
| egrep '^[-0-9A-Za-z_\$\.]+=' | sed 's/^/[Default]/')"
if [ -n "$hidden_default" ]; then
echo "$hidden_default"
fi
# finds sectional and outputs as-is
echo "$(echo "$ini_buffer" | egrep '^\[\s*[-0-9A-Za-z_\$\.]+\s*\]')"
}
The unit test for this StackOverflow post is included in this file:
https://github.com/egberts/bash-ini-file
Source:
https://github.com/egberts/easy-admin/blob/main/test/section-regex.sh
https://cloanto.com/specs/ini/#escapesequences