Postfix manual - master(8)

    MASTER(8)                                                            MASTER(8)

    NAME
           master - Postfix master process

    SYNOPSIS
           master [-Dditvw] [-c config_dir] [-e exit_time]

    DESCRIPTION
           The  master(8) daemon is the resident process that runs Postfix daemons
           on demand: daemons to send or receive messages via the network, daemons
           to  deliver  mail locally, etc.  These daemons are created on demand up
           to a configurable maximum number per service.

           Postfix daemons terminate voluntarily, either after being  idle  for  a
           configurable  amount  of  time, or after having serviced a configurable
           number of requests. Exceptions to this rule are the resident queue man-
           ager,  address  verification  server,  and  the  TLS  session cache and
           pseudo-random number server.

           The behavior of the master(8) daemon is  controlled  by  the  master.cf
           configuration file, as described in master(5).

           Options:

           -c config_dir
                  Read  the main.cf and master.cf configuration files in the named
                  directory instead of the default configuration directory.   This
                  also  overrides the configuration files for other Postfix daemon
                  processes.

           -D     After initialization, run a debugger on the master process.  The
                  debugging  command is specified with the debugger_command in the
                  main.cf global configuration file.

           -d     Do not redirect stdin, stdout or stderr to /dev/null, and do not
                  discard  the  controlling terminal. This must be used for debug-
                  ging only.

           -e exit_time
                  Terminate the master process after exit_time seconds. Child pro-
                  cesses terminate at their convenience.

           -i     Enable  init  mode:  do  not  become  a session or process group
                  leader; and similar to -s, do not redirect stdout to  /dev/null,
                  so  that  "maillog_file  =  /dev/stdout"  works.   This  mode is
                  allowed only if the process ID equals 1.

                  This feature is available in Postfix 3.3 and later.

           -s     Do not redirect stdout to /dev/null,  so  that  "maillog_file  =
                  /dev/stdout" works.

                  This feature is available in Postfix 3.4 and later.

           -t     Test  mode.  Return  a zero exit status when the master.pid lock
                  file does not exist or when that file is not  locked.   This  is
                  evidence that the master(8) daemon is not running.

           -v     Enable  verbose  logging  for debugging purposes. This option is
                  passed on to child processes. Multiple -v options make the soft-
                  ware increasingly verbose.

           -w     Wait in a dummy foreground process, while the real master daemon
                  initializes in  a  background  process.   The  dummy  foreground
                  process  returns  a  zero  exit status only if the master daemon
                  initialization is successful, and if it completes in  a  reason-
                  able amount of time.

                  This feature is available in Postfix 2.10 and later.

           Signals:

           SIGHUP Upon receipt of a HUP signal (e.g., after "postfix reload"), the
                  master process re-reads its configuration files.  If  a  service
                  has  been removed from the master.cf file, its running processes
                  are terminated immediately.  Otherwise,  running  processes  are
                  allowed  to  terminate as soon as is convenient, so that changes
                  in configuration settings affect only new service requests.

           SIGTERM
                  Upon receipt of a TERM signal (e.g., after "postfix abort"), the
                  master  process  passes the signal on to its child processes and
                  terminates.  This is useful for an emergency shutdown.  Normally
                  one  would  terminate only the master ("postfix stop") and allow
                  running processes to finish what they are doing.

    DIAGNOSTICS
           Problems are reported to syslogd(8) or postlogd(8).  The exit status is
           non-zero  in case of problems, including problems while initializing as
           a master daemon process in the background.

    ENVIRONMENT
           MAIL_DEBUG
                  After initialization, start a debugger  as  specified  with  the
                  debugger_command configuration parameter in the main.cf configu-
                  ration file.

           MAIL_CONFIG
                  Directory with Postfix configuration files.

    CONFIGURATION PARAMETERS
           Unlike most Postfix daemon processes, the  master(8)  server  does  not
           automatically  pick  up  changes  to  main.cf. Changes to master.cf are
           never picked up automatically.  Use the "postfix reload" command  after
           a configuration change.

    RESOURCE AND RATE CONTROLS
           default_process_limit (100)
                  The  default maximal number of Postfix child processes that pro-
                  vide a given service.

           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.

           service_throttle_time (60s)
                  How  long  the  Postfix  master(8) waits before forking a server
                  that appears to be malfunctioning.

           Available in Postfix version 2.6 and later:

           master_service_disable (empty)
                  Selectively disable master(8) listener ports by service type  or
                  by service name and type.

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

           daemon_directory (see 'postconf -d' output)
                  The directory with Postfix support programs and daemon programs.

           debugger_command (empty)
                  The external command to execute when a Postfix daemon program is
                  invoked with the -D option.

           inet_interfaces (all)
                  The local network interface  addresses  that  this  mail  system
                  receives mail on.

           inet_protocols (see 'postconf -d' output)
                  The  Internet  protocols Postfix will attempt to use when making
                  or accepting connections.

           import_environment (see 'postconf -d' output)
                  The list of environment  variables  that  a  privileged  Postfix
                  process  will  import  from  a  non-Postfix  parent  process, or
                  name=value environment overrides.

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

           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)
                  A  prefix  that  is  prepended  to  the  process  name in syslog
                  records, so that, for example, "smtpd" becomes "prefix/smtpd".

           Available in Postfix 3.3 and later:

           service_name (read-only)
                  The master.cf service name of a Postfix daemon process.

           Available in Postfix 3.6 and later:

           known_tcp_ports  (lmtp=24,  smtp=25,   smtps=submissions=465,   submis-
           sion=587)
                  Optional setting that avoids lookups in  the  services(5)  data-
                  base.

    FILES
           To  expand  the directory names below into their actual values, use the
           command "postconf config_directory" etc.

           $config_directory/main.cf, global configuration file.
           $config_directory/master.cf, master server configuration file.
           $queue_directory/pid/master.pid, master lock file.
           $data_directory/master.lock, master lock file.

    SEE ALSO
           qmgr(8), queue manager
           verify(8), address verification
           master(5), master.cf configuration file syntax
           postconf(5), main.cf configuration file syntax
           postlogd(8), Postfix logging
           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

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

                                                                         MASTER(8)