MASTER(8) MASTER(8)
NAME
master - Postfix master process
SYNOPSIS
master [-Ddtv] [-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 manager, 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 Post-fix Postfix
fix 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 ter-minal. terminal.
minal. This must be used for debugging only.
-e exit_time
Terminate the master process after exit_time seconds. Child processes terminate at their con-venience. convenience.
venience.
-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 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 pro-cesses processes
cesses 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).
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
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 provide a given service.
max_idle (100s)
The maximum amount of time that an idle Postfix daemon process waits for an incoming connec-tion connection
tion 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 malfunction-ing. malfunctioning.
ing.
MISCELLANEOUS CONTROLS
config_directory (see 'postconf -d' output)
The default location of the Postfix main.cf and master.cf configuration 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 (ipv4)
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 Postfix process will import from a non-Postfix par-ent parent
ent process.
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 (postfix)
The mail system name that is prepended to the process name in syslog records, so that "smtpd"
becomes, for example, "postfix/smtpd".
FILES
/etc/postfix/main.cf, global configuration file.
/etc/postfix/master.cf, master server configuration file.
/var/spool/postfix/pid/master.pid, 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 parameter 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
MASTER(8)
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