Differences

This shows you the differences between two versions of the page.

--- tools:logger:start [2020/11/26 13:04] – [Logging into the Console and into a File] ursgraf
+++ tools:logger:start [2026/04/13 11:12] (current) – [Adding Output to the SysLog] ursgraf
@@ Line 37: / Line 37: @@
 <code cpp>
-  StreamLogWriter w(std::cout);
+  Logger::setDefaultStreamLogger(std::cout);
-  Logger::setDefaultWriter(&w);
+  Logger log = Logger::getLogger();  // this logger will output onto the default ''LogWriter''.
-  Logger log;  // this logger will output onto the default ''LogWriter''.
 </code>
 If you forget to assign a default logger, you will not get logging information from components of the library such as the safety system or the executor.
@@ Line 49: / Line 48: @@
 </code>
 A log file will be created at the given location. Its file name will be appended with the current date and time of the creation of the file.
+===== Adding Output to the SysLog =====
+The simplest way to attach a second sink is via Logger::addWriter(), which promotes the existing writer into a MultiLogWriter automatically:
+<code cpp>
+  Logger::setDefaultStreamLogger(std::cout, "/tmp/myLog");
+  Logger::addWriter(std::make_shared<SysLogWriter>("myLog"));
+  auto log = Logger::getLogger('A');
+  log.show(LogLevel::INFO);  // propagates to both sinks
+</code>
+Alternatively, build the MultiLogWriter explicitly before any getLogger()
+call and hand it to Logger::setDefaultWriter():
+<code cpp>
+  #include <eeros/logger/MultiLogWriter.hpp>
+  auto multi = std::make_shared<MultiLogWriter>();
+  multi->add(std::make_shared<StreamLogWriter>(std::cout, "/tmp/myLog"));
+  multi->add(std::make_shared<SysLogWriter>("myLog"));
+  Logger::setDefaultWriter(multi);
+</code>
+View the produced log entries in the system log with
+<code bash>
+$ journalctl -t myLog
+</code>