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RedHat 9 (Linux i386) - man page for spawn (redhat section 8)

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 daemon provides the Postfix equivalent of inetd.  It listens on a port as speci-
       fied 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  specified  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 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. without interpretation of shell meta charac-
	      ters by a shell command interpreter.

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

DIAGNOSTICS
       The spawn 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 daemon does not talk to the
       external command and thus is not vulnerable to data-driven attacks.

CONFIGURATION PARAMETERS
       The following main.cf parameters are especially relevant to this program. See the  Postfix
       main.cf	file  for  syntax  details and for default values. Use the postfix reload command
       after a configuration change.

Miscellaneous
       export_environment
	      List of names of environment parameters that can be exported  to	non-Postfix  pro-
	      cesses.

       mail_owner
	      The process privileges used while not running an external command.

Resource control
       service_command_time_limit
	      The  amount  of  time the command is allowed to run before it is killed with force.
	      The service name is the name of the entry in the master.cf file. The  default  time
	      limit is given by the global command_time_limit configuration parameter.

SEE ALSO
       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)


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