awk to translate config file to json - json

Question

I have a config file like this one:
[sectionOne]
key1_1=value1_1
key1_n=value1_n
#this is a comment
[sectionTwo]
key2_1=value2_1
key2_n=value2_n
;this is a comment also
[SectionThree]
key3_1=value3_1
key3_n=value3_n
[SectionFor]
...
I need to translate this into json, using minimal shell tools (no perl,python,php, just sed,awk available)
The desired output is :
[
{"sectionOne": { "key1_1": "value1_1","key1_n": "value1_n"} },
{"sectionTwo": { "key2_1": "value2_1","key2_n": "value2_n"} },
{"sectionThree": { "key3_1": "value3_1","key3_n": "value3_n"}}
....
]
I tried several ways/hours, no success
Thank you in advance

Answer 1

There's some inconsistencies between your sample input and desired output so it's hard to be sure but this should be close and easy to tweak if not 100% what you want:
$ cat file
[sectionOne]
key1_1=value1_1
key1_n=value1_n
#this is a comment
[sectionTwo]
key2_1=value2_1
key2_n=value2_n
;this is a comment also
[SectionThree]
key3_1=value3_1
key3_n=value3_n
$
$ cat tst.awk
BEGIN{
FS="="
print "["
}
/^([#;]|[[:space:]]*$)/ {
next
}
gsub(/[][]/,"") {
printf "%s{\"%s\": { ", rs, $0
rs="} },\n"
fs=""
next
}
{
printf "%s\"%s\": \"%s\"", fs, $1, $2
fs=","
}
END{
print rs "]"
}
$
$ awk -f tst.awk file
[
{"sectionOne": { "key1_1": "value1_1","key1_n": "value1_n"} },
{"sectionTwo": { "key2_1": "value2_1","key2_n": "value2_n"} },
{"SectionThree": { "key3_1": "value3_1","key3_n": "value3_n"} },
]

Answer 2

awk 'BEGIN{ print "[" }
/^[#;]/{ next } # Ignore comments
/^\[/{ gsub( "[][]", "" ); printf "%s{\"%s\": { ", s ? "}},\n" : "", $0; n=0; s=1 }
/=/ { gsub( "=", "\":\"" ); printf "%c\"%s\" ", n ? "," : "", $0; n=1 }
END{ print "}}\n]" }
'

Answer 3

Here's a solution in bash using awk:
#!/bin/bash
awk -F"=" 'BEGIN{in_section=0; first_field=0; printf "["}
{
last=length($1);
if ( (substr($1,1,1) == "[") && (substr($1,last, last) == "]")) {
if (in_section==1) {
printf "} },";
}
section=substr($1, 2, last-2);
printf "\n{\"%s\":", section;
printf " {";
first_field=1;
in_section=1;
} else if ( substr($1, 1, 1) == "#" || substr($1, 1, 1) == ";"){
} else if ( ($1 != "") && ($2 != "") ) {
if (first_field==0) {
printf ", ";
}
printf "\"%s\": \"%s\"", $1, $2;
first_field=0;
}
}
END{printf "} }\n]\n"}'