optimize Agunua generator script

Output once per file.

agunua/generate-trust-store.sh

@@ -58,23 +58,21 @@ for cert_file in ../certs/*; do
   fi
 
   # Certificate public key (SPKI) fingerprint
-  echo "$cert" \
+  fingerprint=$(echo "$cert" \
     | openssl x509 -pubkey -noout \
     | openssl pkey -pubin -outform der \
     | openssl dgst -sha256 -binary \
-    | openssl enc -base64 -A \
-    > "$pinning_file"
-  echo >> "$pinning_file"  # newline
+    | openssl enc -base64 -A)
 
   # Expiry date
   enddate=$(echo "$cert" | openssl x509 -enddate -noout | cut -d '=' -f 2)
   enddate=$(date -d "$enddate" +"%Y-%m-%dT%H:%M:%SZ" --utc)
-  echo "$enddate" >> "$pinning_file"
 
   # Start date
   startdate=$(echo "$cert" | openssl x509 -startdate -noout | cut -d '=' -f 2)
   startdate=$(date -d "$startdate" +"%Y-%m-%dT%H:%M:%SZ" --utc)
-  echo "$startdate" >> "$pinning_file"
+
+  printf "%s\n%s\n%s\n" "$fingerprint" "$enddate" "$startdate" > "$pinning_file"
 
 done