Provided by: postfix_2.2.10-1_i386 bug

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
       listens 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
              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 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  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
       solution.

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.

MISCELLANEOUS

       config_directory (seepostconf -doutput)
              The default  location  of  the  Postfix  main.cf  and  master.cf
              configuration files.

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

       export_environment (seepostconf -doutput)
              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
              internal 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 the next service request before exiting.

       max_use (100)
              The maximal number  of  connection  requests  before  a  Postfix
              daemon process terminates.

       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 (seepostconf -doutput)
              The location of the Postfix top-level queue directory.

       syslog_facility (mail)
              The syslog facility of Postfix logging.

       syslog_name (postfix)
              The  mail  system  name that is prepended to the process name in
              syslog  records,  so  that   "smtpd"   becomes,   for   example,
              "postfix/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)