MASTER(5)                                                            MASTER(5)

NAME
       master - Postfix master process configuration file format

DESCRIPTION
       The  Postfix  mail  system  is  implemented by small number of (mostly)
       client commands that are invoked by users, and by a  larger  number  of
       services that run in the background.

       Postfix  services are implemented by daemon processes. These run in the
       background, started on-demand by the master(8) process.  The  master.cf
       configuration  file defines how a client program connects to a service,
       and what daemon program runs when a service is requested.  Most  daemon
       processes  are  short-lived  and  terminate  voluntarily  after serving
       max_use clients, or after inactivity for  max_idle  or  more  units  of
       time.

       All  daemons  specified here must speak a Postfix-internal protocol. In
       order to execute non-Postfix software  use  the  local(8),  pipe(8)  or
       spawn(8) services, or execute the software with inetd(8) or equivalent.

       After changing master.cf you must execute "postfix  reload"  to  reload
       the configuration.

SYNTAX
       The general format of the master.cf file is as follows:

       o      Empty  lines and whitespace-only lines are ignored, as are lines
              whose first non-whitespace character is a `#'.

       o      A logical line starts with  non-whitespace  text.  A  line  that
              starts with whitespace continues a logical line.

       o      Each  logical  line defines a single Postfix service.  Each ser-
              vice is identified by its name  and  type  as  described  below.
              When multiple lines specify the same service name and type, only
              the last one is remembered.  Otherwise, the order  of  master.cf
              service definitions does not matter.

       Each  logical  line  consists  of eight fields separated by whitespace.
       These are described below in the order as they appear in the  master.cf
       file.

       Where  applicable  a  field  of  "-" requests that the built-in default
       value be used. For boolean fields specify "y" or "n"  to  override  the
       default value.

       Service name
              The service name syntax depends on the service type as described
              next.

       Service type
              Specify one of the following service types:

              inet   The service listens on a TCP/IP socket and is  accessible
                     via the network.

                     The  service name is specified as host:port, denoting the
                     host  and  port  on  which  new  connections  should   be
                     accepted.  The  host  part  (and  colon)  may be omitted.
                     Either host or port may be given in  symbolic  form  (see
                     hosts(5)  or  services(5)) or in numeric form (IP address
                     or port number).  Host information may be enclosed inside
                     "[]"; this form is necessary only with IPv6 addresses.

                     Examples:  a  service  named  127.0.0.1:smtp  or ::1:smtp
                     receives mail via the loopback interface only; and a ser-
                     vice  named  10025  accepts connections on TCP port 10025
                     via all interfaces configured  with  the  inet_interfaces
                     parameter.

                     Note:   with   Postfix  version  2.2  and  later  specify
                     "inet_interfaces = loopback-only" in main.cf, instead  of
                     hard-coding  loopback IP address information in master.cf
                     or in main.cf.

              unix   The service listens on a UNIX-domain stream socket and is
                     accessible for local clients only.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in main.cf).

                     On  Solaris 8 and earlier systems the unix type is imple-
                     mented with streams sockets.

              unix-dgram
                     The service listens on a UNIX-domain datagram socket  and
                     is accessible for local clients only.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in main.cf).

              fifo (obsolete)
                     The  service listens on a FIFO (named pipe) and is acces-
                     sible for local clients only.

                     The service name is a pathname relative  to  the  Postfix
                     queue    directory    (pathname   controlled   with   the
                     queue_directory configuration parameter in main.cf).

              pass   The service listens on a UNIX-domain stream  socket,  and
                     is accessible to local clients only. It receives one open
                     connection  (file  descriptor  passing)  per   connection
                     request.

                     The  service  name  is a pathname relative to the Postfix
                     queue   directory   (pathname   controlled    with    the
                     queue_directory configuration parameter in main.cf).

                     On  Solaris 8 and earlier systems the pass type is imple-
                     mented with streams sockets.

                     This feature is available as of Postfix version 2.5.

       Private (default: y)
              Whether a service is internal to Postfix (pathname  starts  with
              private/),  or exposed through Postfix command-line tools (path-
              name starts with public/).  Internet (type inet) services  can't
              be private.

       Unprivileged (default: y)
              Whether the service runs with root privileges or as the owner of
              the  Postfix  system  (the  owner  name  is  controlled  by  the
              mail_owner configuration variable in the main.cf file).

              The  local(8), pipe(8), spawn(8), and virtual(8) daemons require
              privileges.

       Chroot (default: Postfix >= 3.0: n, Postfix < 3.0: y)
              Whether or not the service  runs  chrooted  to  the  mail  queue
              directory (pathname is controlled by the queue_directory config-
              uration variable in the main.cf file).

              Chroot should not be used with the local(8), pipe(8),  spawn(8),
              and virtual(8) daemons.  Although the proxymap(8) server can run
              chrooted, doing so defeats most of the purpose  of  having  that
              service in the first place.

              The files in the examples/chroot-setup subdirectory of the Post-
              fix source show how to set up a Postfix chroot environment on  a
              variety  of  systems.  See  also  BASIC_CONFIGURATION_README for
              issues related to running daemons chrooted.

       Wake up time (default: 0)
              Automatically wake up the named service after the specified num-
              ber  of seconds. The wake up is implemented by connecting to the
              service and sending a wake up request.  A ? at the  end  of  the
              wake-up  time  field  requests  that  no  wake up events be sent
              before the first time a service is used.  Specify 0 for no auto-
              matic wake up.

              The  pickup(8),  qmgr(8)  and flush(8) daemons require a wake up
              timer.

       Process limit (default: $default_process_limit)
              The maximum number of processes that may  execute  this  service
              simultaneously. Specify 0 for no process count limit.

              NOTE:  Some  Postfix  services  must  be  configured  as  a sin-
              gle-process service (for example,  qmgr(8))  and  some  services
              must   be   configured  with  no  process  limit  (for  example,
              cleanup(8)).  These limits must not be changed.

       Command name + arguments
              The command to be executed.  Characters that are special to  the
              shell  such  as  ">"  or  "|"  have no special meaning here, and
              quotes cannot be used to  protect  arguments  containing  white-
              space.  To  protect  whitespace,  use  "{"  and "}" as described
              below.

              The command name is relative to  the  Postfix  daemon  directory
              (pathname  is  controlled  by the daemon_directory configuration
              variable).

              The command argument syntax for specific commands  is  specified
              in the respective daemon manual page.

              The  following command-line options have the same effect for all
              daemon programs:

              -D     Run the daemon under control  by  the  command  specified
                     with the debugger_command variable in the main.cf config-
                     uration file.  See DEBUG_README for hints and tips.

              -o { name = value } (long form, Postfix >= 3.0)
                     Override the named main.cf configuration  parameter.  The
                     parameter  value  can  refer to other parameters as $name
                     etc., just like in main.cf.  See postconf(5) for  syntax.

                     The  "long form" supports whitespace in parameter values.
                     Whitespace after the outer "{", around  "=",  and  before
                     the outer "}" is ignored. Example:

                     /etc/postfix/master.cf:
                         submission inet .... smtpd
                             -o { smtpd_xxx_yyy = text with whitespace... }

                     NOTE:  Over-zealous  use of parameter overrides makes the
                     Postfix configuration hard to  understand  and  maintain.
                     At  a certain point, it might be easier to configure mul-
                     tiple instances of Postfix, instead of configuring multi-
                     ple personalities via master.cf.

              -o name=value (short form)
                     Override  the  named main.cf configuration parameter. The
                     parameter value can refer to other  parameters  as  $name
                     etc.,  just like in main.cf.  See postconf(5) for syntax.

                     The "short form" does not support whitespace  around  the
                     "="  or in parameter values. To specify a parameter value
                     that contains whitespace, use  the  long  form  described
                     above,  or  use commas instead of spaces if the parameter
                     supports that, or specify the value in main.cf. Example:

                     /etc/postfix/master.cf:
                         submission inet .... smtpd
                             -o smtpd_xxx_yyy=$submission_xxx_yyy

                     /etc/postfix/main.cf
                         submission_xxx_yyy = text with whitespace...

                     NOTE: Over-zealous use of parameter overrides  makes  the
                     Postfix  configuration  hard  to understand and maintain.
                     At a certain point, it might be easier to configure  mul-
                     tiple instances of Postfix, instead of configuring multi-
                     ple personalities via master.cf.

              -v     Increase the verbose logging level. Specify  multiple  -v
                     options  to  make  a  Postfix daemon process increasingly
                     verbose.

              Command-line arguments that start with {

              Command-line arguments that contain whitespace

              Command-line arguments that must be empty
                     Specify "{" and "}" around such  arguments  (Postfix  3.0
                     and  later).  The  outer  "{"  and  "}"  will be removed,
                     together with any leading or trailing whitespace  in  the
                     remaining text.

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

README FILES
       BASIC_CONFIGURATION_README, basic configuration
       DEBUG_README, Postfix debugging

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

AUTHOR(S)
       Initial version by
       Magnus Baeck
       Lund Institute of Technology
       Sweden

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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA

                                                                     MASTER(5)