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SPAWN(8)		    System Manager's Manual		      SPAWN(8)

NAME
       spawn - Postfix external	command	spawner

SYNOPSIS
       spawn [generic Postfix daemon options] command_attributes...

DESCRIPTION
       The  spawn(8) daemon provides the Postfix equivalent of inetd.  It lis-
       tens on a port as specified in the Postfix master.cf file and spawns an
       external	 command whenever a connection is established.	The connection
       can be made over	local IPC (such	as UNIX-domain sockets)	or  over  non-
       local  IPC (such	as TCP sockets).  The command's	standard input,	output
       and error streams are connected directly	to the communication endpoint.

       This daemon expects to be run from the master(8)	process	manager.

COMMAND	ATTRIBUTE SYNTAX
       The external command attributes are given in the	master.cf file at  the
       end of a	service	definition.  The syntax	is as follows:

       user=username (required)

       user=username:groupname
	      The  external  command is	executed with the rights of the	speci-
	      fied username.  The software refuses to  execute	commands  with
	      root  privileges,	 or  with  the	privileges  of the mail	system
	      owner. If	groupname is specified,	the corresponding group	ID  is
	      used instead of the group	ID of username.

       argv=command... (required)
	      The  command  to be executed. This must be specified as the last
	      command attribute.  The command is executed directly, i.e. with-
	      out  interpretation  of shell meta characters by a shell command
	      interpreter.

BUGS
       In order	to enforce standard Postfix  process  resource	controls,  the
       spawn(8)	 daemon	runs only one external command at a time.  As such, it
       presents	a noticeable overhead by wasting precious  process  resources.
       The spawn(8) daemon is expected to be replaced by a more	structural so-
       lution.

DIAGNOSTICS
       The spawn(8) daemon reports abnormal child exits.  Problems are	logged
       to syslogd(8).

SECURITY
       This program needs root privilege in order to execute external commands
       as the specified	user. It is therefore security sensitive.  However the
       spawn(8)	 daemon	 does not talk to the external command and thus	is not
       vulnerable to data-driven attacks.

CONFIGURATION PARAMETERS
       Changes to main.cf are picked up	automatically  as  spawn(8)  processes
       run for only a limited amount of	time. Use the command "postfix reload"
       to speed	up a change.

       The text	below provides only a parameter	summary. See  postconf(5)  for
       more details including examples.

       In  the	text  below,  transport	is the first field of the entry	in the
       master.cf file.

RESOURCE AND RATE CONTROL
       transport_time_limit ($command_time_limit)
	      The amount of time the command is	allowed	to run	before	it  is
	      terminated.

	      Postfix  2.4  and	later support a	suffix that specifies the time
	      unit: s (seconds), m (minutes), h	(hours), d (days), w  (weeks).
	      The default time unit is seconds.

MISCELLANEOUS
       config_directory	(see 'postconf -d' output)
	      The  default  location of	the Postfix main.cf and	master.cf con-
	      figuration files.

       daemon_timeout (18000s)
	      How much time a Postfix daemon process may take to handle	a  re-
	      quest before it is terminated by a built-in watchdog timer.

       export_environment (see 'postconf -d' output)
	      The  list	 of  environment variables that	a Postfix process will
	      export to	non-Postfix processes.

       ipc_timeout (3600s)
	      The time limit for sending or receiving information over an  in-
	      ternal communication channel.

       mail_owner (postfix)
	      The  UNIX	 system	 account  that owns the	Postfix	queue and most
	      Postfix daemon processes.

       max_idle	(100s)
	      The maximum amount of time that an idle Postfix  daemon  process
	      waits for	an incoming connection before terminating voluntarily.

       max_use (100)
	      The maximal number of incoming connections that a	Postfix	daemon
	      process will service before terminating voluntarily.

       process_id (read-only)
	      The process ID of	a Postfix command or daemon process.

       process_name (read-only)
	      The process name of a Postfix command or daemon process.

       queue_directory (see 'postconf -d' output)
	      The location of the Postfix top-level queue directory.

       syslog_facility (mail)
	      The syslog facility of Postfix logging.

       syslog_name (see	'postconf -d' output)
	      The mail system name that	is prepended to	the  process  name  in
	      syslog  records,	so  that  "smtpd" becomes, for example,	"post-
	      fix/smtpd".

SEE ALSO
       postconf(5), configuration parameters
       master(8), process manager
       syslogd(8), system logging

LICENSE
       The Secure Mailer license must be distributed with this software.

AUTHOR(S)
       Wietse Venema
       IBM T.J.	Watson Research
       P.O. Box	704
       Yorktown	Heights, NY 10598, USA

								      SPAWN(8)

NAME | SYNOPSIS | DESCRIPTION | COMMAND ATTRIBUTE SYNTAX | BUGS | DIAGNOSTICS | SECURITY | CONFIGURATION PARAMETERS | RESOURCE AND RATE CONTROL | MISCELLANEOUS | SEE ALSO | LICENSE | AUTHOR(S)

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