MASTER(8)

NAME
master - Postfix master process

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

DESCRIPTION
The master 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. The exception to this rule is the resident Postfix queue manager. The behavior of the master daemon is controlled by the master.cf configuration file. The table specifies zero or more servers in the UNIX or INET domain, or servers that take requests from a FIFO. Precise configuration details are given in the master.cf file, and in the manual pages of the respective daemons. Options:

-c config_dir
    Read the main.cf and master.cf configuration files in the named directory instead of the default configuration directory.

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

-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.

-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 daemon is not running.

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

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).

BUGS

ENVIRONMENT

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

MAIL_CONFIG
    Directory with Postfix configuration files.

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

import_environment

export_environment
    Lists of names of environment parameters that can be imported from (exported to) non-Postfix processes.

mail_owner
    The owner of the mail queue and of most Postfix processes.

command_directory
    Directory with Postfix support programs.

daemon_directory
    Directory with Postfix daemon programs.

queue_directory
    Top-level directory of the Postfix queue. This is also the root directory of Postfix daemons that run chrooted.

inet_interfaces
    The network interface addresses that this system receives mail on. You need to stop and start Postfix when this parameter changes.

Resource controls

default_process_limit
    Default limit for the number of simultaneous child processes that provide a given service.

max_idle
    Limit the time in seconds that a child process waits between service requests.

max_use
    Limit the number of service requests handled by a child process.

service_throttle_time
    Time to avoid forking a server that appears to be broken.

FILES
/etc/postfix/main.cf: global configuration file.
/etc/postfix/master.cf: master process configuration file.
/var/spool/postfix/pid/master.pid: master lock file.

SEE ALSO
qmgr(8) queue manager
pickup(8) local mail pickup
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