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<html> <head> </head> <body> <pre>
PIPE(8) PIPE(8)
<b>NAME</b>
pipe - Postfix delivery to external command
<b>SYNOPSIS</b>
<b>pipe</b> [generic Postfix daemon options] command_attributes...
<b>DESCRIPTION</b>
The <b>pipe</b> daemon processes requests from the Postfix queue
manager to deliver messages to external commands. This
program expects to be run from the <a href="master.8.html"><b>master</b>(8)</a> process man-
ager.
The <b>pipe</b> daemon updates queue files and marks recipients
as finished, or it informs the queue manager that delivery
should be tried again at a later time. Delivery problem
reports are sent to the <a href="bounce.8.html"><b>bounce</b>(8)</a> or <a href="defer.8.html"><b>defer</b>(8)</a> daemon as
appropriate.
<b>SINGLE-RECIPIENT</b> <b>DELIVERY</b>
Some external commands cannot handle more than one recipi-
ent per delivery request. Examples of such transports are
pagers, fax machines, and so on.
To prevent Postfix from sending multiple recipients per
delivery request, specify
<i>transport_</i><b>destination</b><i>_</i><b>recipient</b><i>_</i><b>limit</b> <b>=</b> <b>1</b>
in the Postfix <b>main.cf</b> file, where <i>transport</i> is the name
in the first column of the Postfix <b>master.cf</b> entry for the
pipe-based delivery transport.
<b>COMMAND</b> <b>ATTRIBUTE</b> <b>SYNTAX</b>
The external command attributes are given in the <b>master.cf</b>
file at the end of a service definition. The syntax is as
follows:
<b>flags=BFR.</b>> (optional)
Optional message processing flags. By default, a
message is copied unchanged.
<b>B</b> Append a blank line at the end of each mes-
sage. This is required by some mail user
agents that recognize "<b>From</b> " lines only
when preceded by a blank line.
<b>F</b> Prepend a "<b>From</b> <i>sender</i> <i>time_stamp</i>" envelope
header to the message content. This is
expected by, for example, <b>UUCP</b> software.
<b>R</b> Prepend a <b>Return-Path:</b> message header with
the envelope sender address.
<b>.</b> Prepend <b>.</b> to lines starting with "<b>.</b>". This
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PIPE(8) PIPE(8)
is needed by, for example, <b>BSMTP</b> software.
> Prepend > to lines starting with "<b>From</b> ".
This is expected by, for example, <b>UUCP</b> soft-
ware.
<b>user</b>=<i>username</i> (required)
<b>user</b>=<i>username</i>:<i>groupname</i>
The external command is executed with the rights of
the specified <i>username</i>. The software refuses to
execute commands with root privileges, or with the
privileges of the mail system owner. If <i>groupname</i>
is specified, the corresponding group ID is used
instead of the group ID of <i>username</i>.
<b>eol=string</b> (default: <b>\n</b>)
The output record delimiter. Typically one would
use either <b>\r\n</b> or <b>\n</b>. The usual C-style backslash
escape sequences are recognized: <b>\a</b> <b>\b</b> <b>\f</b> <b>\n</b> <b>\r</b> <b>\t</b>
<b>\v</b> <b>\</b><i>octal</i> and <b>\\</b>.
<b>size</b>=<i>size_limit</i> (optional)
Messages greater in size than this limit (in bytes)
will be bounced back to the sender.
<b>argv</b>=<i>command</i>... (required)
The command to be executed. This must be specified
as the last command attribute. The command is exe-
cuted directly, i.e. without interpretation of
shell meta characters by a shell command inter-
preter.
In the command argument vector, the following
macros are recognized and replaced with correspond-
ing information from the Postfix queue manager
delivery request:
<b>${extension</b>}
This macro expands to the extension part of
a recipient address. For example, with an
address <i>user+foo@domain</i> the extension is
<i>foo</i>.
A command-line argument that contains
<b>${extension</b>} expands into as many command-
line arguments as there are recipients.
<b>${mailbox</b>}
This macro expands to the complete local
part of a recipient address. For example,
with an address <i>user+foo@domain</i> the mailbox
is <i>user+foo</i>.
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PIPE(8) PIPE(8)
A command-line argument that contains
<b>${mailbox</b>} expands into as many command-line
arguments as there are recipients.
<b>${nexthop</b>}
This macro expands to the next-hop hostname.
<b>${recipient</b>}
This macro expands to the complete recipient
address.
A command-line argument that contains
<b>${recipient</b>} expands into as many command-
line arguments as there are recipients.
<b>${sender</b>}
This macro expands to the envelope sender
address.
<b>${size</b>}
This macro expands to Postfix's idea of the
message size, which is an approximation of
the size of the message as delivered.
<b>${user</b>}
This macro expands to the username part of a
recipient address. For example, with an
address <i>user+foo@domain</i> the username part is
<i>user</i>.
A command-line argument that contains
<b>${user</b>} expands into as many command-line
arguments as there are recipients.
In addition to the form ${<i>name</i>}, the forms $<i>name</i> and
$(<i>name</i>) are also recognized. Specify <b>$$</b> where a single <b>$</b>
is wanted.
<b>DIAGNOSTICS</b>
Command exit status codes are expected to follow the con-
ventions defined in <<b>sysexits.h</b>>.
Problems and transactions are logged to <b>syslogd</b>(8). Cor-
rupted message files are marked so that the queue manager
can move them to the <b>corrupt</b> queue for further inspection.
<b>SECURITY</b>
This program needs a dual personality 1) to access the
private Postfix queue and IPC mechanisms, and 2) to exe-
cute external commands as the specified user. It is there-
fore security sensitive.
<b>CONFIGURATION</b> <b>PARAMETERS</b>
The following <b>main.cf</b> parameters are especially relevant
3
PIPE(8) PIPE(8)
to this program. See the Postfix <b>main.cf</b> file for syntax
details and for default values. Use the <b>postfix</b> <b>reload</b>
command after a configuration change.
<b>Miscellaneous</b>
<b>export</b><i>_</i><b>environment</b>
List of names of environment parameters that can be
exported to non-Postfix processes.
<b>mail</b><i>_</i><b>owner</b>
The process privileges used while not running an
external command.
<b>Resource</b> <b>controls</b>
In the text below, <i>transport</i> is the first field in a <b>mas-</b>
<b>ter.cf</b> entry.
<i>transport_</i><b>destination</b><i>_</i><b>concurrency</b><i>_</i><b>limit</b>
Limit the number of parallel deliveries to the same
destination, for delivery via the named <i>transport</i>.
The default limit is taken from the <b>default</b><i>_</i><b>desti-</b>
<b>nation</b><i>_</i><b>concurrency</b><i>_</i><b>limit</b> parameter. The limit is
enforced by the Postfix queue manager.
<i>transport_</i><b>destination</b><i>_</i><b>recipient</b><i>_</i><b>limit</b>
Limit the number of recipients per message deliv-
ery, for delivery via the named <i>transport</i>. The
default limit is taken from the <b>default</b><i>_</i><b>destina-</b>
<b>tion</b><i>_</i><b>recipient</b><i>_</i><b>limit</b> parameter. The limit is
enforced by the Postfix queue manager.
<i>transport_</i><b>time</b><i>_</i><b>limit</b>
Limit the time for delivery to external command,
for delivery via the named <b>transport</b>. The default
limit is taken from the <b>command</b><i>_</i><b>time</b><i>_</i><b>limit</b> parame-
ter. The limit is enforced by the Postfix queue
manager.
<b>SEE</b> <b>ALSO</b>
<a href="bounce.8.html">bounce(8)</a> non-delivery status reports
<a href="master.8.html">master(8)</a> process manager
<a href="qmgr.8.html">qmgr(8)</a> queue manager
syslogd(8) system logging
<b>LICENSE</b>
The Secure Mailer license must be distributed with this
software.
<b>AUTHOR(S)</b>
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA
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