etc: Add environment option to run init.d/ashd silently.

[ashd.git] / doc / htparser.doc

diff --git a/doc/htparser.doc b/doc/htparser.doc
index 6e2c239..f400a62 100644 (file)
--- a/doc/htparser.doc
+++ b/doc/htparser.doc
@@ -24,7 +24,8 @@ all the 'ARGS' as command-line arguments. Only after that will
 *htparser* do any daemonizing or chrooting as specified by options.
 
 The root handler must be a persistent program as specified in
-*ashd*(7). If the handler program exits, *htparser* will exit too.
+*ashd*(7). If the handler program exits, *htparser* will exit too,
+following the procedure described below under SIGNALS.
 
 PORT SPECIFICATION
 ------------------
@@ -37,9 +38,9 @@ PORT SPECIFICATION
 Currently, the available 'HANDLERs' are *plain* and *ssl*, for
 handling plain TCP connections and SSL/TLS-protected connections,
 respectively. For details regarding the arguments that each handler
-accept, simply run *htparser* with 'HANDLER'*:help*. For example, the
-command "`htparser ssl:help`" will display help for the *ssl* handler to
-standard output and then exit.
+accepts, simply run *htparser* with 'HANDLER'*:help*. For example, the
+command "`htparser ssl:help`" will display help for the *ssl* handler
+to standard output and then exit.
 
 The port specifications must be followed by the `--` argument to
 distinguish them from the root handler specification.
@@ -63,23 +64,62 @@ OPTIONS
        Daemonize after all specified ports have been successfully
        bound and the root handler has been started.
 
-*-u*::
+*-u* 'USER'::
 
        Change UID to 'USER' once all specified ports have been
        successfully bound and the root handler has been
        started. 'USER' must be specified symbolically (i.e. not as a
        numeric UID).
 
-*-r*::
+*-r* 'ROOT'::
 
        Change root directory to 'ROOT' once all specified ports have
        been successfully bound and the root handler has been started.
 
-*-p*::
+*-p* 'PIDFILE'::
 
        After having daemonized, write the PID of the new process to
        'PIDFILE'.
 
+If the *-u*, *-r* or *-p* option is presented with an empty argument,
+it will be treated as if the option had not been given.
+
+SIGNALS
+-------
+
+SIGTERM, SIGINT::
+
+       Upon first reception, `htparser` closes all listening ports
+       and the socket to the root handler, but continues to serve all
+       currently ongoing requests until none remain, not keeping the
+       connections open for keep-alive. Upon second reception,
+       `htparser` shuts down completely.
+
+PID-FILE PROTOCOL
+-----------------
+
+If the *-p* option is used to create a PID file, `htparser` will
+follow a simple protocol to allow state monitoring for clean shutdown
+purposes. When `htparser` is signalled to terminate, as described
+under SIGNALS, then it appends a single newline at the end of the PID
+file. Once all outstanding connections have been terminated, then
+`htparser` will truncate the PID file to zero size just prior to
+exiting. Thus, init scripts or other state-monitoring tools can know
+that `htparser` is serving remaining connections as long as the PID
+file contains two lines (the last of which is empty).
+
+Further, when `htparser` starts, it does not overwrite the contents of
+an existing PID file, but rather creates a new file, replacing the old
+file. Thus, if a new instance of `htparser` is started while a
+previous instance is still running (or serving remaining connections),
+the PID file for the new instance will not be truncated when the
+previous instance terminates.
+
+The reason for the somewhat unorthodox protocol is that it works by
+simply keeping the PID file open in the running process, allowing the
+protocol to work without pathnames, and therefore even if `htparser`
+is instructed to change root directory with the *-r* option.
+
 EXAMPLES
 --------