ini2json

#!/usr/bin/env bash

# if args are passed, use first arg as file to process. otherwise assume STDIN
if [ $# -ge 1 -a -f "$1" ]; then
  infile="$1"; shift;
else
  infile="-"
fi

# here be my awk program!
IFS='' PROG=$(cat <<'EOAWK'
  function wrap(x) {
    if (length(x) > 0 && x ~ /^[0-9]?\.?[0-9]*$/) return x;
    return sprintf("\"%s\"", x);
  }

  function json(data, k, txt, sep, i, out) {
    out="";
    i=0;
    if (!isarray(data)) return wrap(data)
    out=out sprintf("{ ")
    for (k in data) {
      txt=isarray(data[k]) ? json(data[k]) : wrap(data[k])
      sep=(++i < length(data)) ? ", " : " ";
      out=out sprintf("\"%s\": %s%s", k, txt, sep);
    };
    out=out sprintf("}");
    return out;
  }

  BEGIN { FS="="; output=""; }

  $0 ~ /^[:space:]*\[.+\][:space:]*$/ {
    section=gensub(/^[:space:]*\[(.+)\][:space:]*$/, "\\1", 1)
  }

  $0 !~ /^#|^[:space:]*\[.+\][:space:]*$/ && length($1) > 0 {
    if (length(section) > 0) {
      data[section][$1]=$2
    } else {
      data[$1]=$2
    }
  }

  END {
    print json(data)
  }
EOAWK
)

# run it! append any remaining arguments to awk
cat $infile | gawk $PROG "$@"