doc: Added manpage for errlogger.

[ashd.git] / doc / callscgi.doc

callscgi(1)
===========

NAME
----
callscgi - SCGI request handler for ashd(7)

SYNOPSIS
--------
*callscgi* [*-h*] [*-N* 'RETRIES'] [*-i* 'ID'] [*-u* 'UNIXPATH'] [*-t* \[HOST:]'TCPPORT'] ['PROGRAM' ['ARGS'...]]

DESCRIPTION
-----------

The *callscgi* handler uses SCGI to call an external handler for
requests. *callscgi* is a persistent handler, as defined in *ashd*(7).

Depending on which arguments are given, *callscgi* will run in one of
four operating modes.

If an address option is given (see OPTIONS below), but the 'PROGRAM'
argument is not given, *callscgi* will run in client mode. In client
mode, *callscgi* will try to connect to a SCGI server listening to the
given address. If it cannot connect, it will exit, except when failing
only once, in which case it will retry according to the *-N* option,
described below.

If no address option is given, but the 'PROGRAM' argument is given,
*callscgi* will run in anonymous mode. In anonymous mode, *callscgi*
will create a Unix socket listening on some more-or-less random
address, and start the given 'PROGRAM', passing the listening socket
on its standard input, expecting the program to start accepting
connections on that socket. *callscgi* will then connect to that
socket for each request. If such a connection is refused, the child
program will be assumed to have crashed, and *callscgi* will restart
it. Also in anonymous mode, *callscgi*, will try and kill the child
program whenever *callscgi* itself exits for whatever reason (commonly
because its own control socket is closed by its parent handler).

If both an address option and the 'PROGRAM' argument are given, but
the *-N* option is not given, *callscgi* will run in launching
mode. In launching mode, *callscgi* will try to connect to a SCGI
server at the given address, but if (and only if) that fails, it will
create a socket listening to the given address, and start the given
'PROGRAM', passing the listening socket on its standard input,
expecting the program to start accepting connections on that
socket. Unlike in anonymous mode, *callscgi* will leave any child
process it has started running even when *callscgi* itself exits.

If both an address option, the 'PROGRAM' argument and the *-N* option
are given, *callscgi* will run in mixed mode. In mixed mode,
*callscgi* will try to connect to a SCGI server at the given address,
but if that fails, it will start the given 'PROGRAM'. Unlike in
launching mode, however, *callscgi* will not create the listening
socket itself, but will assume that the 'PROGRAM' will create it
independently (probably based on any 'ARGS' passed to it). When
'PROGRAM' is launched, *callscgi* will try to connect to the given
address once per second, up to 'RETRIES' times. If the connection
cannot succeed even after 'RETRIES' attempts, *callscgi* will exit.

OPTIONS
-------

*-h*::

	Print a brief help message to standard output and exit.

*-u* 'UNIXPATH'::

	Use 'UNIXPATH' as the Unix socket address of the SCGI server.

*-t* \[HOST:]'TCPPORT'::

	Use the given TCP/IP address as the SCGI server address. If
	'HOST' is not given, use `localhost` instead. 'TCPPORT' may be
	given symbolically.

*-i* 'ID'::

	Use 'ID' to create a reasonably unique pathname to use as the
	Unix socket address of the SCGI server. This option is mainly
	intended for use as a convenience in launching mode, where the
	SCGI server does not need to know the actual address it is
	listening to (since it gets passed the listening socket on
	standard input) to start SCGI servers that can persist even if
	*callscgi* exits for some reason.

*-N* 'RETRIES'::

	In client mode and mixed mode, try to connect 'RETRIES' times,
	once per second, to the SCGI server before giving up. If both
	an address option and the 'PROGRAM' argument are given, the
	presence of the *-N* option determines whether to run in
	launching mode or mixed mode, as described above.

SIGNALS
-------

SIGINT, SIGTERM::

	Exit cleanly, sending SIGTERM to any child process started if
	running in anonymous mode, as described above.

AUTHOR
------
Fredrik Tolf <fredrik@dolda2000.com>

SEE ALSO
--------
*ashd*(7)