daemon: Add ability to write a PID file

The PID file will only be written if the daemon is called with the
`--detach` command line argument and a `--pidfile /some/file/path`
argument.

1 files changed, 11 insertions, 1 deletions

diff --git a/src/daemonizer/posix_daemonizer.inl b/src/daemonizer/posix_daemonizer.inl
index f8be15dda..506c7766f 100644
--- a/src/daemonizer/posix_daemonizer.inl
+++ b/src/daemonizer/posix_daemonizer.inl
@@ -43,6 +43,10 @@ namespace daemonizer
       "detach"
     , "Run as daemon"
     };
+    const command_line::arg_descriptor<std::string> arg_pidfile = {
+      "pidfile"
+    , "File path to write the daemon's PID to (optional, requires --detach)"
+    };
     const command_line::arg_descriptor<bool> arg_non_interactive = {
       "non-interactive"
     , "Run non-interactive"
@@ -55,6 +59,7 @@ namespace daemonizer
     )
   {
     command_line::add_arg(normal_options, arg_detach);
+    command_line::add_arg(normal_options, arg_pidfile);
     command_line::add_arg(normal_options, arg_non_interactive);
   }
 
@@ -80,7 +85,12 @@ namespace daemonizer
     if (command_line::has_arg(vm, arg_detach))
     {
       tools::success_msg_writer() << "Forking to background...";
-      posix::fork();
+      std::string pidfile;
+      if (command_line::has_arg(vm, arg_pidfile))
+      {
+        pidfile = command_line::get_arg(vm, arg_pidfile);
+      }
+      posix::fork(pidfile);
       auto daemon = executor.create_daemon(vm);
       return daemon.run();
     }