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 attempt to become a session or process
              group leader; and to force termination, set an  explicit  signal
              handler  instead  of  relying on the default signal action. This
              mode is allowed only if the process ID equals 1.

       -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). 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  network  interface addresses that this mail system receives
              mail on.

       inet_protocols (all)
              The Internet protocols Postfix will attempt to use  when  making
              or accepting connections.

       import_environment (see 'postconf -d' output)
              The  list  of  environment  parameters 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.

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
       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)