.TH PIPE 8
.ad
.fi
.SH NAME
pipe
\-
Postfix delivery to external command
.SH SYNOPSIS
.na
.nf
\fBpipe\fR [generic Postfix daemon options] command_attributes...
.SH DESCRIPTION
.ad
.fi
The \fBpipe\fR daemon processes requests from the Postfix queue
manager to deliver messages to external commands.
This program expects to be run from the \fBmaster\fR(8) process
manager.
Message attributes such as sender address, recipient address and
next-hop host name can be specified as command-line macros that are
expanded before the external command is executed.
The \fBpipe\fR 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 \fBbounce\fR(8) or \fBdefer\fR(8) daemon as appropriate.
.SH SINGLE-RECIPIENT DELIVERY
.na
.nf
.ad
.fi
Some external commands cannot handle more than one recipient
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
.ti +4
\fItransport\fB_destination_recipient_limit = 1\fR
in the Postfix \fBmain.cf\fR file, where \fItransport\fR
is the name in the first column of the Postfix \fBmaster.cf\fR
entry for the pipe-based delivery transport.
.SH COMMAND ATTRIBUTE SYNTAX
.na
.nf
.ad
.fi
The external command attributes are given in the \fBmaster.cf\fR
file at the end of a service definition. The syntax is as follows:
.IP "\fBflags=BDFORhqu.>\fR (optional)"
Optional message processing flags. By default, a message is
copied unchanged.
.RS
.IP \fBB\fR
Append a blank line at the end of each message. This is required
by some mail user agents that recognize "\fBFrom \fR" lines only
when preceded by a blank line.
.IP \fBD\fR
Prepend a "\fBDelivered-To: \fIrecipient\fR" message header with the
envelope recipient address. Note: for this to work, the
\fItransport\fB_destination_recipient_limit\fR must be 1.
.IP \fBF\fR
Prepend a "\fBFrom \fIsender time_stamp\fR" envelope header to
the message content.
This is expected by, for example, \fBUUCP\fR software.
.IP \fBO\fR
Prepend an "\fBX-Original-To: \fIrecipient\fR" message header
with the recipient address as given to Postfix. Note: for this to
work, the \fItransport\fB_destination_recipient_limit\fR must be 1.
.IP \fBR\fR
Prepend a \fBReturn-Path:\fR message header with the envelope sender
address.
.IP \fBh\fR
Fold the command-line \fB$recipient\fR domain name and \fB$nexthop\fR
host name to lower case.
This is recommended for delivery via \fBUUCP\fR.
.IP \fBq\fR
Quote white space and other special characters in the command-line
\fB$sender\fR and \fB$recipient\fR address localparts (text to the
left of the right-most \fB@\fR character), according to an 8-bit
transparent version of RFC 822.
This is recommended for delivery via \fBUUCP\fR or \fBBSMTP\fR.
.sp
The result is compatible with the address parsing of command-line
recipients by the Postfix \fBsendmail\fR mail submission command.
.sp
The \fBq\fR flag affects only entire addresses, not the partial
address information from the \fB$user\fR, \fB$extension\fR or
\fB$mailbox\fR command-line macros.
.IP \fBu\fR
Fold the command-line \fB$recipient\fR address localpart (text to
the left of the right-most \fB@\fR character) to lower case.
This is recommended for delivery via \fBUUCP\fR.
.IP \fB.\fR
Prepend \fB.\fR to lines starting with "\fB.\fR". This is needed
by, for example, \fBBSMTP\fR software.
.IP \fB>\fR
Prepend \fB>\fR to lines starting with "\fBFrom \fR". This is expected
by, for example, \fBUUCP\fR software.
.RE
.IP "\fBuser\fR=\fIusername\fR (required)"
.IP "\fBuser\fR=\fIusername\fR:\fIgroupname\fR"
The external command is executed with the rights of the
specified \fIusername\fR. The software refuses to execute
commands with root privileges, or with the privileges of the
mail system owner. If \fIgroupname\fR is specified, the
corresponding group ID is used instead of the group ID of
\fIusername\fR.
.IP "\fBeol=string\fR (optional, default: \fB\en\fR)"
The output record delimiter. Typically one would use either
\fB\er\en\fR or \fB\en\fR. The usual C-style backslash escape
sequences are recognized: \fB\ea \eb \ef \en \er \et \ev
\e\fIoctal\fR and \fB\e\e\fR.
.IP "\fBsize\fR=\fIsize_limit\fR (optional)"
Messages greater in size than this limit (in bytes) will be bounced
back to the sender.
.IP "\fBargv\fR=\fIcommand\fR... (required)"
The command to be executed. This must be specified as the
last command attribute.
The command is executed directly, i.e. without interpretation of
shell meta characters by a shell command interpreter.
.sp
In the command argument vector, the following macros are recognized
and replaced with corresponding information from the Postfix queue
manager delivery request:
.RS
.IP \fB${\fBextension\fR}\fR
This macro expands to the extension part of a recipient address.
For example, with an address \fIuser+foo@domain\fR the extension is
\fIfoo\fR.
.sp
A command-line argument that contains \fB${\fBextension\fR}\fR expands
into as many command-line arguments as there are recipients.
.sp
This information is modified by the \fBu\fR flag for case folding.
.IP \fB${\fBmailbox\fR}\fR
This macro expands to the complete local part of a recipient address.
For example, with an address \fIuser+foo@domain\fR the mailbox is
\fIuser+foo\fR.
.sp
A command-line argument that contains \fB${\fBmailbox\fR}\fR
expands into as many command-line arguments as there are recipients.
.sp
This information is modified by the \fBu\fR flag for case folding.
.IP \fB${\fBnexthop\fR}\fR
This macro expands to the next-hop hostname.
.sp
This information is modified by the \fBh\fR flag for case folding.
.IP \fB${\fBrecipient\fR}\fR
This macro expands to the complete recipient address.
.sp
A command-line argument that contains \fB${\fBrecipient\fR}\fR
expands into as many command-line arguments as there are recipients.
.sp
This information is modified by the \fBhqu\fR flags for quoting
and case folding.
.IP \fB${\fBsender\fR}\fR
This macro expands to the envelope sender address.
.sp
This information is modified by the \fBq\fR flag for quoting.
.IP \fB${\fBsize\fR}\fR
This macro expands to Postfix's idea of the message size, which
is an approximation of the size of the message as delivered.
.IP \fB${\fBuser\fR}\fR
This macro expands to the username part of a recipient address.
For example, with an address \fIuser+foo@domain\fR the username
part is \fIuser\fR.
.sp
A command-line argument that contains \fB${\fBuser\fR}\fR expands
into as many command-line arguments as there are recipients.
.sp
This information is modified by the \fBu\fR flag for case folding.
.RE
.PP
In addition to the form ${\fIname\fR}, the forms $\fIname\fR and
$(\fIname\fR) are also recognized. Specify \fB$$\fR where a single
\fB$\fR is wanted.
.SH DIAGNOSTICS
.ad
.fi
Command exit status codes are expected to
follow the conventions defined in <\fBsysexits.h\fR>.
Problems and transactions are logged to \fBsyslogd\fR(8).
Corrupted message files are marked so that the queue manager
can move them to the \fBcorrupt\fR queue for further inspection.
.SH SECURITY
.na
.nf
.fi
.ad
This program needs a dual personality 1) to access the private
Postfix queue and IPC mechanisms, and 2) to execute external
commands as the specified user. It is therefore security sensitive.
.SH CONFIGURATION PARAMETERS
.na
.nf
.ad
.fi
The following \fBmain.cf\fR parameters are especially relevant to
this program. See the Postfix \fBmain.cf\fR file for syntax details
and for default values. Use the \fBpostfix reload\fR command after
a configuration change.
.SH Miscellaneous
.ad
.fi
.IP \fBexport_environment\fR
List of names of environment parameters that can be exported
to non-Postfix processes.
.IP \fBmail_owner\fR
The process privileges used while not running an external command.
.SH "Resource controls"
.ad
.fi
In the text below, \fItransport\fR is the first field in a
\fBmaster.cf\fR entry.
.IP \fItransport\fB_destination_concurrency_limit\fR
Limit the number of parallel deliveries to the same destination,
for delivery via the named \fItransport\fR. The default limit is
taken from the \fBdefault_destination_concurrency_limit\fR parameter.
The limit is enforced by the Postfix queue manager.
.IP \fItransport\fB_destination_recipient_limit\fR
Limit the number of recipients per message delivery, for delivery
via the named \fItransport\fR. The default limit is taken from
the \fBdefault_destination_recipient_limit\fR parameter.
The limit is enforced by the Postfix queue manager.
.IP \fItransport\fB_time_limit\fR
Limit the time for delivery to external command, for delivery via
the named \fBtransport\fR. The default limit is taken from the
\fBcommand_time_limit\fR parameter.
The limit is enforced by the pipe delivery agent.
.SH SEE ALSO
.na
.nf
bounce(8) non-delivery status reports
master(8) process manager
qmgr(8) queue manager
syslogd(8) system logging
.SH LICENSE
.na
.nf
.ad
.fi
The Secure Mailer license must be distributed with this software.
.SH AUTHOR(S)
.na
.nf
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA