+DAEMON INVOCATION:
+
+The daemon can be invoked with no arguments, in which case it will not
+fork or detach itself. This is suitable for running from init and
+similar arrangements.
+
+With -daemon it will attempt to detach itself from the controlling
+terminal and fork/exit so that control returns at startup.
+
+In both cases diagnostics which prevent correct startup will appear on
+stderr.
+
+SYSLOG MESSAGES:
+
+The daemon issues diagnostics of various kinds to syslog, usually with
+facility LOG_DAEMON (though this can be changed in daemon.h if you want).
+The syslog levels used are:
+ debug - verbose messages about the activity of the userv daemon.
+ info - two log message about the nature and outcome of each request.
+ notice - messages about the status of the daemon, including the
+ startup message and the hourly socket check messages.
+ warning - if the uservd exits because it believes that it no longer
+ controls the rendezvous socket (ie, its socket has become
+ orphaned), this level will receive messages indicating why
+ the daemon believes this and notifying of its shutdown.
+ err - a believed-recoverable error condition was detected by the
+ userv server in itself, the client or the operating system
+ (this includes resource shortages). The uservd will try to
+ continue.
+ crit - the uservd detected a non-recoverable error condition
+ after startup and will exit.
+ alert - not used.
+ emerg - not used.
+
+The service configuration language has the facility to direct error
+and warning messages to syslog. The default facility and level is
+user.err, but the author of the configuration file(s) can override
+this.
+
+DAEMON EXIT STATUS:
+
+The daemon's exit code will reflect how well things went:
+
+ 0 - The daemon was asked to detach itself from the controlling
+ terminal and this appears to have been done successfully.
+ 1* - The daemon got a SIGTERM or SIGINT and shut itself down.
+ 2* - The daemon believes that it was no longer the uservd and so has
+ exited to clean itself up.
+ 3 - uservd was started with incorrect arguments.
+ 4 - A system call failure or other environmental problem occurred
+ during startup.
+ 5* - There was a non-recoverable error after startup; the uservd had
+ to exit.
+ 6 - The daemon was asked to detach itself, but its detaching child
+ died for some unexpected reason.
+
+ SIGABRT/SIGIOT* - an unexpected internal error, usually caused by a
+ bug in uservd. This can also occur if an attempt to block signals
+ using sigprocmask fails.
+
+Outcomes marked * are not possible if the daemon is asked to detach
+itself - these exit statuses will be reaped by init instead.
+
+The daemon's per-request children will note the success level of its
+request in its exit status. This will not usually be logged unless it
+is higher than those listed below; they are presented here for
+completeness and as programming documentation.
+
+ 2 - The connection was just an internal version check.
+
+ 4 - The client requested that the service be disconnected. This
+ includes normal termination, which is achieved by having the
+ server tell the client that the service has completed and waiting
+ for the client to tell it to disconnect.
+
+ 8 - The client closed its end of the socket when this would not
+ usually have been expected, causing an EPIPE or unexpected EOF in
+ the server. This is not an error condition - it can happen, for
+ example, if the client receives a fatal signal of some kind from
+ its execution environment (eg its controlling terminal).
+
+ 12 - The service failed onm the service side in an expected and
+ controlled manner, for example because it was rejected in the
+ configuration files.
+
+ 16 - A fatal system call failure or other general error occurred,
+ which ought not to have happened at all, barring system resource
+ shortages.
+
+ 20 - The client sent invalid data to the server, after the client
+ dropped all its system privilege. On some systems this can be
+ caused by a malicious calling user.
+
+ SIGABRT/SIGIOT - The client sent invalid data to the server before it
+ dropped all its system privileges, or some other unexpected
+ internal error occurred. This can also occur if an attempt to
+ block signals using sigprocmask fails.
+
+ 0-3,5-7,9-11,13-15,17-19 are not currently used.
+