1MASTER(8) System Manager's Manual MASTER(8)
2
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 become a session or process group
47 leader; and similar to -s, do not redirect stdout to /dev/null,
48 so that "maillog_file = /dev/stdout" works. This mode is al‐
49 lowed only if the process ID equals 1.
50 This feature is available in Postfix 3.3 and later.
52 -s Do not redirect stdout to /dev/null, so that "maillog_file =
54 /dev/stdout" works.
55 This feature is available in Postfix 3.4 and later.
57 -t Test mode. Return a zero exit status when the master.pid lock
59 file does not exist or when that file is not locked. This is
60 evidence that the master(8) daemon is not running.
61 -v Enable verbose logging for debugging purposes. This option is
63 passed on to child processes. Multiple -v options make the soft‐
64 ware increasingly verbose.
65 -w Wait in a dummy foreground process, while the real master daemon
67 initializes in a background process. The dummy foreground
68 process returns a zero exit status only if the master daemon
69 initialization is successful, and if it completes in a reason‐
70 able amount of time.
71 This feature is available in Postfix 2.10 and later.
73 Signals:
75 SIGHUP Upon receipt of a HUP signal (e.g., after "postfix reload"), the
77 master process re-reads its configuration files. If a service
78 has been removed from the master.cf file, its running processes
79 are terminated immediately. Otherwise, running processes are
80 allowed to terminate as soon as is convenient, so that changes
81 in configuration settings affect only new service requests.
82 SIGTERM
84 Upon receipt of a TERM signal (e.g., after "postfix abort"), the
85 master process passes the signal on to its child processes and
86 terminates. This is useful for an emergency shutdown. Normally
87 one would terminate only the master ("postfix stop") and allow
88 running processes to finish what they are doing.
89
91 Problems are reported to syslogd(8) or postlogd(8). The exit status is
92 non-zero in case of problems, including problems while initializing as
93 a master daemon process in the background.
94
96 MAIL_DEBUG
97 After initialization, start a debugger as specified with the de‐
98 bugger_command configuration parameter in the main.cf configura‐
99 tion file.
100 MAIL_CONFIG
102 Directory with Postfix configuration files.
103
105 Unlike most Postfix daemon processes, the master(8) server does not au‐
106 tomatically pick up changes to main.cf. Changes to master.cf are never
107 picked up automatically. Use the "postfix reload" command after a con‐
108 figuration change.
109
111 default_process_limit (100)
112 The default maximal number of Postfix child processes that pro‐
113 vide a given service.
114 max_idle (100s)
116 The maximum amount of time that an idle Postfix daemon process
117 waits for an incoming connection before terminating voluntarily.
118 max_use (100)
120 The maximal number of incoming connections that a Postfix daemon
121 process will service before terminating voluntarily.
122 service_throttle_time (60s)
124 How long the Postfix master(8) waits before forking a server
125 that appears to be malfunctioning.
126 Available in Postfix version 2.6 and later:
128 master_service_disable (empty)
130 Selectively disable master(8) listener ports by service type or
131 by service name and type.
132
134 config_directory (see 'postconf -d' output)
135 The default location of the Postfix main.cf and master.cf con‐
136 figuration files.
137 daemon_directory (see 'postconf -d' output)
139 The directory with Postfix support programs and daemon programs.
140 debugger_command (empty)
142 The external command to execute when a Postfix daemon program is
143 invoked with the -D option.
144 inet_interfaces (all)
146 The network interface addresses that this mail system receives
147 mail on.
148 inet_protocols (see 'postconf -d output')
150 The Internet protocols Postfix will attempt to use when making
151 or accepting connections.
152 import_environment (see 'postconf -d' output)
154 The list of environment parameters that a privileged Postfix
155 process will import from a non-Postfix parent process, or
156 name=value environment overrides.
157 mail_owner (postfix)
159 The UNIX system account that owns the Postfix queue and most
160 Postfix daemon processes.
161 process_id (read-only)
163 The process ID of a Postfix command or daemon process.
164 process_name (read-only)
166 The process name of a Postfix command or daemon process.
167 queue_directory (see 'postconf -d' output)
169 The location of the Postfix top-level queue directory.
170 syslog_facility (mail)
172 The syslog facility of Postfix logging.
173 syslog_name (see 'postconf -d' output)
175 A prefix that is prepended to the process name in syslog
176 records, so that, for example, "smtpd" becomes "prefix/smtpd".
177 Available in Postfix 3.3 and later:
179 service_name (read-only)
181 The master.cf service name of a Postfix daemon process.
182 Available in Postfix 3.6 and later:
184 known_tcp_ports (lmtp=24, smtp=25, smtps=submissions=465, submis‐
186 sion=587)
187 Optional setting that avoids lookups in the services(5) data‐
188 base.
189
191 To expand the directory names below into their actual values, use the
192 command "postconf config_directory" etc.
193 $config_directory/main.cf, global configuration file.
195 $config_directory/master.cf, master server configuration file.
196 $queue_directory/pid/master.pid, master lock file.
197 $data_directory/master.lock, master lock file.
198
200 qmgr(8), queue manager
201 verify(8), address verification
202 master(5), master.cf configuration file syntax
203 postconf(5), main.cf configuration file syntax
204 postlogd(8), Postfix logging
205 syslogd(8), system logging
206
208 The Secure Mailer license must be distributed with this software.
209
211 Wietse Venema
212 IBM T.J. Watson Research
213 P.O. Box 704
214 Yorktown Heights, NY 10598, USA
215 Wietse Venema
217 Google, Inc.
218 111 8th Avenue
219 New York, NY 10011, USA
220 MASTER(8)