1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3<html> <head> 4<meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> 5<title> Postfix manual - spawn(8) </title> 6</head> <body> <pre> 7SPAWN(8) SPAWN(8) 8 9<b>NAME</b> 10 spawn - Postfix external command spawner 11 12<b>SYNOPSIS</b> 13 <b>spawn</b> [generic Postfix daemon options] command_attributes... 14 15<b>DESCRIPTION</b> 16 The <a href="spawn.8.html"><b>spawn</b>(8)</a> daemon provides the Postfix equivalent of 17 <b>inetd</b>. It listens on a port as specified in the Postfix 18 <a href="master.5.html"><b>master.cf</b></a> file and spawns an external command whenever a 19 connection is established. The connection can be made 20 over local IPC (such as UNIX-domain sockets) or over non- 21 local IPC (such as TCP sockets). The command's standard 22 input, output and error streams are connected directly to 23 the communication endpoint. 24 25 This daemon expects to be run from the <a href="master.8.html"><b>master</b>(8)</a> process 26 manager. 27 28<b>COMMAND ATTRIBUTE SYNTAX</b> 29 The external command attributes are given in the <a href="master.5.html"><b>master.cf</b></a> 30 file at the end of a service definition. The syntax is as 31 follows: 32 33 <b>user</b>=<i>username</i> (required) 34 35 <b>user</b>=<i>username</i>:<i>groupname</i> 36 The external command is executed with the rights of 37 the specified <i>username</i>. The software refuses to 38 execute commands with root privileges, or with the 39 privileges of the mail system owner. If <i>groupname</i> 40 is specified, the corresponding group ID is used 41 instead of the group ID of <i>username</i>. 42 43 <b>argv</b>=<i>command</i>... (required) 44 The command to be executed. This must be specified 45 as the last command attribute. The command is exe- 46 cuted directly, i.e. without interpretation of 47 shell meta characters by a shell command inter- 48 preter. 49 50<b>BUGS</b> 51 In order to enforce standard Postfix process resource con- 52 trols, the <a href="spawn.8.html"><b>spawn</b>(8)</a> daemon runs only one external command 53 at a time. As such, it presents a noticeable overhead by 54 wasting precious process resources. The <a href="spawn.8.html"><b>spawn</b>(8)</a> daemon is 55 expected to be replaced by a more structural solution. 56 57<b>DIAGNOSTICS</b> 58 The <a href="spawn.8.html"><b>spawn</b>(8)</a> daemon reports abnormal child exits. Prob- 59 lems are logged to <b>syslogd</b>(8). 60 61<b>SECURITY</b> 62 This program needs root privilege in order to execute 63 external commands as the specified user. It is therefore 64 security sensitive. However the <a href="spawn.8.html"><b>spawn</b>(8)</a> daemon does not 65 talk to the external command and thus is not vulnerable to 66 data-driven attacks. 67 68<b>CONFIGURATION PARAMETERS</b> 69 Changes to <a href="postconf.5.html"><b>main.cf</b></a> are picked up automatically as <a href="spawn.8.html"><b>spawn</b>(8)</a> 70 processes run for only a limited amount of time. Use the 71 command "<b>postfix reload</b>" to speed up a change. 72 73 The text below provides only a parameter summary. See 74 <a href="postconf.5.html"><b>postconf</b>(5)</a> for more details including examples. 75 76 In the text below, <i>transport</i> is the first field of the 77 entry in the <a href="master.5.html"><b>master.cf</b></a> file. 78 79<b>RESOURCE AND RATE CONTROL</b> 80 <b><a href="postconf.5.html#transport_time_limit"><i>transport</i>_time_limit</a> ($<a href="postconf.5.html#command_time_limit">command_time_limit</a>)</b> 81 The amount of time the command is allowed to run 82 before it is terminated. 83 84 Postfix 2.4 and later support a suffix that speci- 85 fies the time unit: s (seconds), m (minutes), h 86 (hours), d (days), w (weeks). The default time unit 87 is seconds. 88 89<b>MISCELLANEOUS</b> 90 <b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b> 91 The default location of the Postfix <a href="postconf.5.html">main.cf</a> and 92 <a href="master.5.html">master.cf</a> configuration files. 93 94 <b><a href="postconf.5.html#daemon_timeout">daemon_timeout</a> (18000s)</b> 95 How much time a Postfix daemon process may take to 96 handle a request before it is terminated by a 97 built-in watchdog timer. 98 99 <b><a href="postconf.5.html#export_environment">export_environment</a> (see 'postconf -d' output)</b> 100 The list of environment variables that a Postfix 101 process will export to non-Postfix processes. 102 103 <b><a href="postconf.5.html#ipc_timeout">ipc_timeout</a> (3600s)</b> 104 The time limit for sending or receiving information 105 over an internal communication channel. 106 107 <b><a href="postconf.5.html#mail_owner">mail_owner</a> (postfix)</b> 108 The UNIX system account that owns the Postfix queue 109 and most Postfix daemon processes. 110 111 <b><a href="postconf.5.html#max_idle">max_idle</a> (100s)</b> 112 The maximum amount of time that an idle Postfix 113 daemon process waits for an incoming connection 114 before terminating voluntarily. 115 116 <b><a href="postconf.5.html#max_use">max_use</a> (100)</b> 117 The maximal number of incoming connections that a 118 Postfix daemon process will service before termi- 119 nating voluntarily. 120 121 <b><a href="postconf.5.html#process_id">process_id</a> (read-only)</b> 122 The process ID of a Postfix command or daemon 123 process. 124 125 <b><a href="postconf.5.html#process_name">process_name</a> (read-only)</b> 126 The process name of a Postfix command or daemon 127 process. 128 129 <b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b> 130 The location of the Postfix top-level queue direc- 131 tory. 132 133 <b><a href="postconf.5.html#syslog_facility">syslog_facility</a> (mail)</b> 134 The syslog facility of Postfix logging. 135 136 <b><a href="postconf.5.html#syslog_name">syslog_name</a> (see 'postconf -d' output)</b> 137 The mail system name that is prepended to the 138 process name in syslog records, so that "smtpd" 139 becomes, for example, "postfix/smtpd". 140 141<b>SEE ALSO</b> 142 <a href="postconf.5.html">postconf(5)</a>, configuration parameters 143 <a href="master.8.html">master(8)</a>, process manager 144 syslogd(8), system logging 145 146<b>LICENSE</b> 147 The Secure Mailer license must be distributed with this 148 software. 149 150<b>AUTHOR(S)</b> 151 Wietse Venema 152 IBM T.J. Watson Research 153 P.O. Box 704 154 Yorktown Heights, NY 10598, USA 155 156 SPAWN(8) 157</pre> </body> </html> 158