linux: show the manpage on -h or --help

chrome/app/chrome_dll_main.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // TODO(port): the ifdefs in here are a first step towards trying to determine
 // the correct abstraction for all the OS functionality required at this
 // stage of process initialization. It should not be taken as a final
 // abstraction.
 
 #include "build/build_config.h"
@@ skipping 320 matching lines @@
 #endif
 
   const CommandLine& parsed_command_line = *CommandLine::ForCurrentProcess();
 
 #if defined(OS_WIN)
   // Must do this before any other usage of command line!
   if (HasDeprecatedArguments(parsed_command_line.command_line_string()))
     return 1;
 #endif
 
+#if defined(OS_LINUX)
+  // Show the man page on --help or -h.
+  if (parsed_command_line.HasSwitch(L"help") ||
+      parsed_command_line.HasSwitch(L"h")) {
+    FilePath binary(parsed_command_line.argv()[0]);
+    int ret = execlp("man", "man", binary.BaseName().value().c_str(), NULL);
+    LOG(FATAL) << "execlp failed: " << strerror(ret);
+  }
+#endif
+
 #if defined(OS_POSIX)
   // Always ignore SIGPIPE.  We check the return value of write().
   CHECK(signal(SIGPIPE, SIG_IGN) != SIG_ERR);
 #endif  // OS_POSIX
 
   int browser_pid;
   std::wstring process_type =
     parsed_command_line.GetSwitchValue(switches::kProcessType);
   if (process_type.empty()) {
     browser_pid = base::GetCurrentProcId();
@@ skipping 171 matching lines @@
   _CrtDumpMemoryLeaks();
 #endif  // _CRTDBG_MAP_ALLOC
 
   _Module.Term();
 #endif
 
   logging::CleanupChromeLogging();
 
   return rv;
 }