MASTER(8) System Manager's Manual MASTER(8)
NAME
master - Postfix master process
SYNOPSIS
master [-c config_dir] [-e exit_time] [-D] [-t] [-v]
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 termi-
nates. This is useful for an emergency shutdown. Normally one would terminate only the master (postfix stop) and allow running pro-
cesses 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.
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
MASTER(8)