MASTER(8) System Manager's Manual MASTER(8)
master - Postfix master process
master [-Dtv] [-c config_dir] [-e exit_time]
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
The behavior of the master daemon is controlled by the master.cf con-
figuration file. The table specifies zero or more servers in the UNIX
or INET domain, or servers that take requests from a FIFO. Precise con-
figuration details are given in the master.cf file, and in the manual
pages of the respective daemons.
Read the main.cf and master.cf configuration files in the named
directory instead of the default configuration directory.
Terminate the master process after exit_time seconds. Child pro-
cesses 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 soft-
ware increasingly verbose.
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.
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.
Problems are reported to syslogd(8).
After initialization, start a debugger as specified with the
debugger_command configuration parameter in the main.cf configu-
Directory with Postfix configuration files.
The following main.cf parameters are especially relevant to this pro-
gram. See the Postfix main.cf file for syntax details and for default
values. Use the postfix reload command after a configuration change.
Lists of names of environment parameters that can be imported
from (exported to) non-Postfix processes.
The owner of the mail queue and of most Postfix processes.
Directory with Postfix support programs.
Directory with Postfix daemon programs.
Top-level directory of the Postfix queue. This is also the root
directory of Postfix daemons that run chrooted.
The network interface addresses that this system receives mail
on. You need to stop and start Postfix when this parameter
Default limit for the number of simultaneous child processes
that provide a given service.
Limit the time in seconds that a child process waits between
Limit the number of service requests handled by a child process.
Time to avoid forking a server that appears to be broken.
/etc/postfix/main.cf: global configuration file.
/etc/postfix/master.cf: master process configuration file.
/var/spool/postfix/pid/master.pid: master lock file.
qmgr(8) queue manager
pickup(8) local mail pickup
syslogd(8) system logging
The Secure Mailer license must be distributed with this software.
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA