cbmreco: Add flag to write logs to file.

algo/base/Options.cxx

@@ -54,7 +54,9 @@ Options::Options(int argc, char** argv)
       "set log level (debug, info, warning, error, fatal)")
     ("monitor,m", po::value(&fMonitorUri)->value_name("<uri>")->implicit_value("file:cout"),
       "URI specifying monitor output (e.g. file:/tmp/monitor.txt, influx1:login:8086:cbmreco_status). Prints to cout when no argument is given. Monitor is disabled when flag is not set.")
-    ("num-ts,n", po::value(&fNumTimeslices)->default_value(-1)->value_name("<num>"),
+    ("log-file,L", po::value(&fLogFile)->value_name("<file>"),
+      "write log messages to file")
+    ("num-ts,n", po::value<int>(&fNumTimeslices)->default_value(-1)->value_name("<num>"),
       "Stop after <num> timeslices (-1 = all)")
     ("skip-ts,s", po::value(&fSkipTimeslices)->default_value(0)->value_name("<num>"),
       "Skip first <num> timeslices")
@@ -71,11 +73,19 @@ Options::Options(int argc, char** argv)
   po::variables_map vm;
   po::command_line_parser parser {argc, argv};
   parser.options(cmdline_options);
-  po::store(parser.run(), vm);
+  try {
+    auto result = parser.run();
+    po::store(result, vm);
+  }
+  catch (const std::exception& e) {
+    std::cerr << "Error: " << e.what() << std::endl;
+    std::cerr << "Use '-h' to display all valid options." << std::endl;
+    std::exit(EXIT_FAILURE);
+  }
 
-  if (vm.count("help")) {
-    std::cerr << cmdline_options << std::endl;
-    std::exit(0);
+  if (vm.count("help") > 0) {
+    std::cout << cmdline_options << std::endl;
+    std::exit(EXIT_SUCCESS);
   }
 
   try {
@@ -83,7 +93,7 @@ Options::Options(int argc, char** argv)
   }
   catch (const po::required_option& e) {
     std::cerr << "Error: " << e.what() << std::endl;
-    std::cerr << cmdline_options << std::endl;
-    std::exit(1);
+    std::cerr << "Use '-h' to display all valid options." << std::endl;
+    std::exit(EXIT_FAILURE);
   }
 }