110-startlogs.sh: better continuation of existing log file (even if empty).

tools/startup.d/110-startlogs.sh

@@ -6,6 +6,8 @@
 # Author: Kovács Zoltán <kovacsz@marcusconsulting.hu>
 # License: GNU/GPL v3+ (https://www.gnu.org/licenses/gpl-3.0.en.html)
 #
+# 2025-06-01 v0.4
+# fix: better continuation of existing log file (even if empty).
 # 2025-03-29 v0.3
 # mod: no longer repeats existing log lines.
 # 2025-02-26 v0.2
@@ -103,10 +105,11 @@ else
 		[[ -n "$logline" ]] \
 		    && timestamp="$(echo "$logline" | "$CUT" -d' ' -f1 2>/dev/null)" \
 		    || timestamp="invalid"
-		# Checks the validity.
+		# If the log does not contain a valid last timestamp, we write log lines
+		# created since the last time the container was started.
 		[[ $("$DATE" -d "$timestamp" >/dev/null 2>&1; echo $?) -eq 0 ]] \
 		    && since="$timestamp" \
-		    || since="1970-01-01T00:00Z"
+		    || since="$("$DOCKER" inspect -f '{{ .State.StartedAt }}' $container)"
 		# Only logs the new lines (actually repeats the last one - TODO!).
         	"$DOCKER" logs -t --since "$since" -f $container >> "$BASE_DIR/$LOGDIR/$service.log" 2>&1 &
 	    fi