NAME
master - Postfix master process
SYNOPSIS
master [-Ddtvw] [-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 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 debugging
only.
- -e exit_time
- Terminate the master process after exit_time
seconds. Child processes terminate at their convenience.
- -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.
- -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 reasonable 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
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 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
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 (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 Postfix process
will import from a non-Postfix parent 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 (see 'postconf -d' output)
- The mail system name that is prepended to the process name
in syslog records, so that "smtpd" becomes, for example,
"postfix/smtpd".
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