1MASTER(8) System Manager's Manual MASTER(8)
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6 master - Postfix master process
7
9 master [-Dditvw] [-c config_dir] [-e exit_time]
10
12 The master(8) daemon is the resident process that runs Postfix daemons
13 on demand: daemons to send or receive messages via the network, daemons
14 to deliver mail locally, etc. These daemons are created on demand up
15 to a configurable maximum number per service.
16 Postfix daemons terminate voluntarily, either after being idle for a
18 configurable amount of time, or after having serviced a configurable
19 number of requests. Exceptions to this rule are the resident queue man‐
20 ager, address verification server, and the TLS session cache and
21 pseudo-random number server.
22 The behavior of the master(8) daemon is controlled by the master.cf
24 configuration file, as described in master(5).
25 Options:
27 -c config_dir
29 Read the main.cf and master.cf configuration files in the named
30 directory instead of the default configuration directory. This
31 also overrides the configuration files for other Postfix daemon
32 processes.
33 -D After initialization, run a debugger on the master process. The
35 debugging command is specified with the debugger_command in the
36 main.cf global configuration file.
37 -d Do not redirect stdin, stdout or stderr to /dev/null, and do not
39 discard the controlling terminal. This must be used for debug‐
40 ging only.
41 -e exit_time
43 Terminate the master process after exit_time seconds. Child pro‐
44 cesses terminate at their convenience.
45 -i Enable init mode: do not attempt to become a session or process
47 group leader; and to force termination, set an explicit signal
48 handler instead of relying on the default signal action. This
49 mode is allowed only if the process ID equals 1.
50 -t Test mode. Return a zero exit status when the master.pid lock
52 file does not exist or when that file is not locked. This is
53 evidence that the master(8) daemon is not running.
54 -v Enable verbose logging for debugging purposes. This option is
56 passed on to child processes. Multiple -v options make the soft‐
57 ware increasingly verbose.
58 -w Wait in a dummy foreground process, while the real master daemon
60 initializes in a background process. The dummy foreground
61 process returns a zero exit status only if the master daemon
62 initialization is successful, and if it completes in a reason‐
63 able amount of time.
64 This feature is available in Postfix 2.10 and later.
66 Signals:
68 SIGHUP Upon receipt of a HUP signal (e.g., after "postfix reload"), the
70 master process re-reads its configuration files. If a service
71 has been removed from the master.cf file, its running processes
72 are terminated immediately. Otherwise, running processes are
73 allowed to terminate as soon as is convenient, so that changes
74 in configuration settings affect only new service requests.
75 SIGTERM
77 Upon receipt of a TERM signal (e.g., after "postfix abort"), the
78 master process passes the signal on to its child processes and
79 terminates. This is useful for an emergency shutdown. Normally
80 one would terminate only the master ("postfix stop") and allow
81 running processes to finish what they are doing.
82
84 Problems are reported to syslogd(8). The exit status is non-zero in
85 case of problems, including problems while initializing as a master
86 daemon process in the background.
87
89 MAIL_DEBUG
90 After initialization, start a debugger as specified with the
91 debugger_command configuration parameter in the main.cf configu‐
92 ration file.
93 MAIL_CONFIG
95 Directory with Postfix configuration files.
96
98 Unlike most Postfix daemon processes, the master(8) server does not
99 automatically pick up changes to main.cf. Changes to master.cf are
100 never picked up automatically. Use the "postfix reload" command after
101 a configuration change.
102
104 default_process_limit (100)
105 The default maximal number of Postfix child processes that pro‐
106 vide a given service.
107 max_idle (100s)
109 The maximum amount of time that an idle Postfix daemon process
110 waits for an incoming connection before terminating voluntarily.
111 max_use (100)
113 The maximal number of incoming connections that a Postfix daemon
114 process will service before terminating voluntarily.
115 service_throttle_time (60s)
117 How long the Postfix master(8) waits before forking a server
118 that appears to be malfunctioning.
119 Available in Postfix version 2.6 and later:
121 master_service_disable (empty)
123 Selectively disable master(8) listener ports by service type or
124 by service name and type.
125
127 config_directory (see 'postconf -d' output)
128 The default location of the Postfix main.cf and master.cf con‐
129 figuration files.
130 daemon_directory (see 'postconf -d' output)
132 The directory with Postfix support programs and daemon programs.
133 debugger_command (empty)
135 The external command to execute when a Postfix daemon program is
136 invoked with the -D option.
137 inet_interfaces (all)
139 The network interface addresses that this mail system receives
140 mail on.
141 inet_protocols (all)
143 The Internet protocols Postfix will attempt to use when making
144 or accepting connections.
145 import_environment (see 'postconf -d' output)
147 The list of environment parameters that a privileged Postfix
148 process will import from a non-Postfix parent process, or
149 name=value environment overrides.
150 mail_owner (postfix)
152 The UNIX system account that owns the Postfix queue and most
153 Postfix daemon processes.
154 process_id (read-only)
156 The process ID of a Postfix command or daemon process.
157 process_name (read-only)
159 The process name of a Postfix command or daemon process.
160 queue_directory (see 'postconf -d' output)
162 The location of the Postfix top-level queue directory.
163 syslog_facility (mail)
165 The syslog facility of Postfix logging.
166 syslog_name (see 'postconf -d' output)
168 A prefix that is prepended to the process name in syslog
169 records, so that, for example, "smtpd" becomes "prefix/smtpd".
170 Available in Postfix 3.3 and later:
172 service_name (read-only)
174 The master.cf service name of a Postfix daemon process.
175
177 To expand the directory names below into their actual values, use the
178 command "postconf config_directory" etc.
179 $config_directory/main.cf, global configuration file.
181 $config_directory/master.cf, master server configuration file.
182 $queue_directory/pid/master.pid, master lock file.
183 $data_directory/master.lock, master lock file.
184
186 qmgr(8), queue manager
187 verify(8), address verification
188 master(5), master.cf configuration file syntax
189 postconf(5), main.cf configuration file syntax
190 syslogd(8), system logging
191
193 The Secure Mailer license must be distributed with this software.
194
196 Wietse Venema
197 IBM T.J. Watson Research
198 P.O. Box 704
199 Yorktown Heights, NY 10598, USA
200 Wietse Venema
202 Google, Inc.
203 111 8th Avenue
204 New York, NY 10011, USA
205 MASTER(8)