How to parse and convert ini file into bash array variables?

Gawk accepts regular expressions as field delimiters. The following eliminates spaces around the equal sign, but preserves them in the rest of the line. Quotes are added around the value so those spaces, if any, are preserved when the Bash assignment is performed. I'm assuming that the section names will be numeric variables, but if you're using Bash 4, it would be easy to adapt this to use associative arrays with the section names themselves as the indices.

awk -F ' *= *' '{ if ($1 ~ /^\[/) section=$1; else if ($1 !~ /^$/) print $1 section "=" "\"" $2 "\"" }'

Note that you may want to also do the space removal that Khaled shows (on only $1 and section) since Bash variable names can't contain spaces.

Also, this method won't work if the values contain equal signs.

Another technique would be to use a Bash while read loop and perform the assignments as the file is read, using declare which is safe from most malicious content.

foobar=1
barfoo=2  # or you could increment an index variable each time a section is found
while IFS='= ' read var val
do
    if [[ $var == \[*] ]]
    then
        section=$var
    elif [[ $val ]]
    then
        declare "$var$section=$val"
    fi
done < filename

Again, associative arrays could fairly easily be supported.

I would use simple python script for this job since it has built in INI parser:

#!/usr/bin/env python

import sys, ConfigParser

config = ConfigParser.ConfigParser()
config.readfp(sys.stdin)

for sec in config.sections():
    print "declare -A %s" % (sec)
    for key, val in config.items(sec):
        print '%s[%s]="%s"' % (sec, key, val)

and then in bash:

#!/bin/bash

# load the in.ini INI file to current BASH - quoted to preserve line breaks
eval "$(cat in.ini  | ./ini2arr.py)"

# test it:
echo ${barfoo[session]}

Sure, there are shorter implementations in awk, but I think this is more readable and easier to maintain.

If you want to eliminate the extra spaces, you can use the built-in function gsub. For example, you can add:

gsub(/ /, "", $1);

This will remove all spaces. If you want to remove spaces at the beginning or end of token, you can use

gsub(/^ /, "", $1);
gsub(/ $/, "", $1);

Here's a pure bash solution.

This is a new and improved version of what chilladx posted:

https://github.com/albfan/bash-ini-parser

For a really easy to follow initial example: After you download this, just copy the files bash-ini-parser, and scripts/file.ini to the same directory, then create a client test script using the example I've provided below to that same directory as well.

source ./bash-ini-parser
cfg_parser "./file.ini"
cfg_section_sec2
echo "var2=$var2"
echo "var5[*]=${var5[*]}"
echo "var5[1]=${var5[1]}"

Here are some further improvements I made to the bash-ini-parser script...

If you want to be able to read ini files with Windows line endings as well as Unix, add this line to the cfg_parser function immediately following the one which reads the file:

ini=$(echo "$ini"|tr -d '\r') # remove carriage returns

If you want to read files which have restrictive access permissions, add this optional function:

# Enable the cfg_parser to read "locked" files
function sudo_cfg_parser {

    # Get the file argument
    file=$1

    # If not "root", enable the "sudo" prefix
    sudoPrefix=
    if [[ $EUID -ne 0 ]]; then sudoPrefix=sudo; fi

    # Save the file permissions, then "unlock" the file
    saved_permissions=$($sudoPrefix stat -c %a $file)
    $sudoPrefix chmod 777 $file

    # Call the standard cfg_parser function
    cfg_parser $file

    # Restore the original permissions
    $sudoPrefix chmod $saved_permissions $file  
}

Always assuming to have Python's ConfigParser around, one may build a shell helper function like this:

get_network_value()
{
    cat <<EOF | python
import ConfigParser
config = ConfigParser.ConfigParser()
config.read('network.ini')
print (config.get('$IFACE','$param'))
EOF
}

$IFACEand $param are the section respectively the parameter.

This helper then allows calls like:

address=`param=address get_network_value` || exit 1
netmask=`param=netmask get_network_value` || exit 1
gateway=`param=gateway get_network_value` || exit 1

Hope this helps!

If you have Git available and are OK with the constraint of not being able to use underscores in the key names, you can use git config as a general-purpose INI parser / editor.

It will handle parsing out the key/value pair from around the = and discard insignificant whitespace, plus you get comments (both ; and #) and type coercion basically for free. I have included a complete working example for the OP's input .ini and desired output (Bash associative arrays), below.

However, given a config file like this

; mytool.ini
[section1]
    inputdir = ~/some/dir
    enablesomefeature = true
    enablesomeotherfeature = yes
    greeting = Bonjour, Monde!

[section2]
    anothersetting = 42

…provided you just need a quick-and-dirty solution, and aren't married to the idea of having the settings in a Bash associative array, you could get away with as little as:

eval $(git config -f mytool.ini --list | tr . _)

# or if 'eval' skeeves you out excessively
source <(git config -f mytool.ini --list | tr . _)

which creates environment variables named sectionname_variablename in the current environment. This, of course, only works if you can trust that none of your values will ever contain a period or whitespace (see below for a more robust solution).

Other simple examples

Fetching arbitrary values, using a shell function to save typing:

function myini() { git config -f mytool.ini; }

An alias would be OK, here, too, but those are not normally expanded in a shell script [1], and anyway aliases are superseded by shell functions "for almost every purpose," [2], according to the Bash man page.

myini --list
# result:
# section1.inputdir=~/some/dir
# section1.enablesomefeature=true
# section1.enablesomeotherfeature=yes
# section2.anothersetting=42

myini --get section1.inputdir
# result:
# ~/some/dir

With the --type option, you can "canonicalize" specific settings as integers, booleans, or paths (automatically expanding ~):

myini --get --type=path section1.inputdir  # value '~/some/dir'
# result:
# /home/myuser/some/dir

myini --get --type=bool section1.enablesomeotherfeature  # value 'yes'
# result:
# true

Slightly more robust quick-and-dirty example

Make all variables in mytool.ini available as SECTIONNAME_VARIABLENAME in the current environment, preserving internal whitespace in key values:

source <(
    git config -f mytool.ini --list \
      | sed 's/\([^.]*\)\.\(.*\)=\(.*\)/\U\1_\2\E="\3"/'
)

What the sed expression is doing, in English, is

1. finding a bunch of non-period characters up to a period, remembering that as \1, then
2. finding a bunch of characters up to an equals sign, remembering that as \2, and
3. finding all the characters after the equals sign as \3
4. finally, in the replacement string
   • the section name + variable name is upper-cased, and
   • the value part is double-quoted, in case it contains characters that have special meaning to the shell if unquoted (like whitespace)

The \U and \E sequences in the replacement string (which upper-case that part of the replacement string) are GNU sed extension. On macOS and BSD, you'd just use multiple -e expressions to achieve the same effect.

Dealing with embedded quotes and whitespace in the section names (which git config allows) is left as an exercise for the reader. :)

Using section names as keys into a Bash associative array

Given:

; foo.ini
[foobar]
session=foo
path=/some/path

[barfoo]
session=bar
path=/some/path

This will produce the result the OP is asking for, simply by rearranging some of the captures in the sed replacement expression, and will work fine without GNU sed:

source <(
    git config -f foo.ini --list \
      | sed 's/\([^.]*\)\.\(.*\)=\(.*\)/declare -A \2["\1"]="\3"/'
)

I predict there could be some challenges with quoting for a real-world .ini file, but it works for the provided example. Result:

declare -p {session,path}
# result:
# declare -A session=([barfoo]="bar" [foobar]="foo" )
# declare -A path=([barfoo]="/some/path" [foobar]="/some/path" )

With a lot of help from the answers in this post, as well as other on this site and some foogle (not a typo), I have come up with the following "solution" quoted because of the caveat at the end. I would prefer a pure bash method but everything I have seen either does not seem to work with my bash version or is rather cumbersome.

This fits the final category but still is less cumbersome than other options.

filename: functions

getSetting() {
    cat /dev/stdin | awk -v section="$1" -v key="$2" '
        BEGIN {
        if (length(key) > 0) { params=2 }
        else if (length(section) > 0) { params=1 }
        else { params=0 }
        }
        match($0,/;/) { next }
        match($0,/#/) { next }
        match($0,/^\[(.+)\]$/){
        current=substr($0, RSTART+1, RLENGTH-2)
        found=current==section
        if (params==0) { print current }
        }
        match($0,/(.+)=(.+)/) {
        if (found) {
            if (params==2 && key==substr($1, 0, length(key))) { print substr($0, length(key)+2) }
            if (params==1) { printf "%s\n",$1,$3 }
        }
    }'
}

filename: options.ini

[default]
 opt1=some value that matters not here
 opt2=another such value

[section2]
 opt1=something different
 opt2=another something different

filename: options This is the file that calls the function. so functions needs to be sourced here.

#!/bin/bash
appPath="$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd)"

# Need to source the functions file to be able to use the above function
source $appPath/functions

defaultOpt1=$(cat $appPath/options/file.ini | getSetting 'default' 'opt1')
defaultOpt2=$(cat $appPath/options/file.ini | getSetting 'default' 'opt2')

sec2opt1=$(cat $appPath/options/file.ini | getSetting 'section2' 'opt1')
sec2opt2=$(cat $appPath/options/file.ini | getSetting 'section2' 'opt2')

And finally to access you need to source options:

filename: someapplication

#!/bin/bash
app="$(cd "$(dirname "${BASH_SOURCE[0]}")" &>/dev/null && pwd)"

# don't need to source functions again, but do need to source "options" file
source $app/sources/options

echo "$opt1 \n$opt2 \n$sec2opt1 \n$sec2opt2"

I have looked at other options to "automatically" generate the variable by parsing the whole INI file but I am not sure there is anything really simple.

With this way, you can update the variables as you need to add them to your ini file. But, the caveat being it's not scalable in any meaningful way yet.