BASH Script using awk to extract a key

Question

I'm creating dkim private & public keys openssl genrsa -out dkim1024.key 1024 openssl rsa -in dkim1024.key -out dkim1024.pub -pubout -outform PEM

I have a bash script using awk to extract a key file KEY=/usr/bin/awk 'NR>1{a[++k]=$0}END{for(i=1;i<k;i++)print a[i]}' file.key

file.key contents

-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY
8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCS
WKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1O
HYu6TIqqzlqtadfafafafdas
-----END PUBLIC KEY-----

I need to remove the lines. -----BEGIN PUBLIC KEY----- -----END PUBLIC KEY----- I've done this in my awk cmd but when I echo $KEY There are spaces. I'm guessing that these are return chars but I'm not sure how to get rid of them but preserve the key.

sh-3.2# echo $KEY
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY 8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCS WKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1O HYu6TIqqzlqtadfafafafdas

Thanks

Answer 1

You get spaces instead of lines because of word splitting. You should quote your variable around double-quotes

echo "$KEY"

This could be an alternative solution too:

awk '/-END PUBLIC KEY-/ { p = 0 }; p; /-BEGIN PUBLIC KEY-/ { p = 1 }' file.key

Output:

MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY
8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCS
WKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1O
HYu6TIqqzlqtadfafafafdas

The solution would also work even if there are other lines before or after the block.

You can also do it with Bash itself:

#!/bin/bash

FILE='file.key'  ## Or FILE=$1

KEY=()
while IFS=$' \t\r\n' read -r LINE; do
    [[ $LINE == *'-END PUBLIC KEY-'* ]] && P=0
    (( P )) && KEY+=("$LINE")  ## Store every line as an array element.
    [[ $LINE == *'-BEGIN PUBLIC KEY-'* ]] && P=1
done < "$FILE"

echo --------------------

printf '%s\n' "${KEY[@]}"

echo --------------------

IFS= eval 'MERGED_KEY="${KEY[*]}"'  ## Merge key without spaces.

echo "$MERGED_KEY"

Output:

--------------------
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY
8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCS
WKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1O
HYu6TIqqzlqtadfafafafdas
--------------------
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCSWKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1OHYu6TIqqzlqtadfafafafdas

Answer 2

It's not clear if you WANT the input lines all concatenated into one output line or not so take your pick based on your script:

$ key=$(awk 'NR>1{a[++k]=$0}END{for(i=1;i<k;i++)print a[i]}' file)
$ echo "$key"
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY
8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCS
WKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1O
HYu6TIqqzlqtadfafafafdas

$ key=$(awk 'NR>1{a[++k]=$0}END{for(i=1;i<k;i++)printf "%s",a[i]}' file)
$ echo "$key"
MIGfMA0GCSqasdfadaBAQUAA4GNADCBiQKBsdfadsfsDgrKE5D2atbGtaqVmAZwzy1YNY8pUYgF6qQ4zecRrpk3Uam52asdfafasdasdfasgwYAA0x3roKIYAeHFFrFm9aCSWKpM+na/03akmpewn4cjT4sm9qTHP0q/VM/YtHy3rGkPj+xzOKgO9rzyZo3E1a1OHYu6TIqqzlqtadfafafafdas

or use @konsolebox's awk solution, changing p; to p{printf "%s",$0} if you want the lines concatenated.