slocal(1)slocal(1)NAMEslocal - MH receive-mail hooks
SYNOPSISslocal $HOME/.maildelivery [-form formfile] [switches for postproc]
address... [-help]
/usr/lib/mh/rcvpack file [-help]
/usr/lib/mh/rcvtty [command...] [-help]
DESCRIPTION
A receive-mail hook is a program that is run whenever you receive a
mail message. You do not invoke the hook yourself; it is invoked on
your behalf by sendmail, when you include the following line in your
file in your home directory:
"| /usr/lib/mh/slocal -user username"
The file, which is an ordinary ASCII file, controls how local delivery
is performed. This file is read by slocal.
The format of each line in the file is:
field pattern action result string
These components are explained below: The name of a field that is to be
searched for a pattern. This is any field in the headers of the mes‐
sage that might be present. In addition, the following special fields
are also defined:
source: the out-of-band sender information
addr: the address that was used to cause delivery to the recipi‐
ent
default: this matches only if the message has not been delivered
yet
*: this always matches The sequence of characters to match in
the specified field. Matching is case-insensitive but not Regu‐
lar Expression-based. The action to take to deliver the mes‐
sage. This is one of the following: Append the message to the
file named by string using the standard maildrop delivery
process. If the message can be appended to the file, then this
action succeeds. When writing to the file, a new field is added:
This field indicates the date and time at which the message was
appended to the file. Pipe the message as the standard input to
the command named by string. The Bourne shell, sh(1), is used to
interpret the string. Prior to giving the string to the shell,
it is expanded with the following built-in variables:
$(sender): the return address for the message
$(address): the address that was used to cause delivery to the
recipient
$(size): the size of the message in bytes
$(reply-to): either the Reply-To: or From: field of the message
$(info): miscellaneous out-of-band information
When a process is invoked, its environment is as follows: the
user/group id's are set to recipient's id's; the working direc‐
tory is the recipient's directory; the umask is 0077; the
process has no /dev/tty; the standard input is set to the mes‐
sage; the standard output and diagnostic output are set to
/dev/null; all other file-descriptors are closed; the environ‐
ment variables $USER, $HOME, and $SHELL are set appropriately;
no other environment variables exist.
The process is given a certain amount of time to execute. If the
process does not exit within this limit, it is terminated. The
amount of time is calculated as ((size x 60) + 300) seconds,
where size is the number of bytes in the message.
The exit status of the process is consulted to determine the
success of the action. An exit status of 0 means that the action
succeeded. Any other exit status (or abnormal termination) means
that the action failed.
In order to avoid any time limitations, you might implement a
process that began by forking. The parent would return the
appropriate value immediately, and the child could continue to
do whatever it wanted for as long as it wanted. This approach
should only be used if you do not care about the outcome of the
action, because the success or failure of the child process can‐
not be passed back to slocal. However, if the parent is going to
return a non-zero exit status, then this approach can lead to
quicker delivery into your maildrop. This is similar to pipe,
but executes the command directly, after built-in variable
expansion, without assistance from the shell. This action
always succeeds. Indicates how the action should be performed.
The following values are valid: Perform the action. If the
action succeeded, then the message is considered delivered.
Perform the action. Regardless of the outcome of the action, the
message is not considered delivered. Perform the action only if
the message has not been delivered. If the action succeeded,
then the message is considered delivered.
The file is always read completely, so that several matches can be made
and several actions can be taken. The file must be owned either by the
user or by root, and must be writable only by the owner. If the file
cannot be found, or does not perform an action which delivers the mes‐
sage, then the file /usr/lib/mh/maildelivery is read according to the
same rules. This file must be owned by the root and must be writable
only by the root. If this file cannot be found or does not perform an
action which delivers the message, then standard delivery to the user's
maildrop, /usr/spool/mail/$USER, is performed.
Arguments in the file are separated by a comma (,) or by white space.
Since double quotes are honored, these characters may be included in a
single argument by enclosing the entire argument in double quotes (").
A double quote can be included by preceding it with a back-slash.
Four programs are currently available: rcvdist redistributes incoming
messages to additional recipients; rcvpack saves incoming messages in a
packf(1) file; and rcvtty notifies the user of incoming messages. The
fourth program, rcvstore, is described in the rcvstore(1) reference
page. They all reside in the /usr/lib/mh directory.
The rcvdist program resends a copy of the message to all of the
addresses listed on its command line. It uses the format string facil‐
ity described in mh-format(4).
The rcvpack program appends a copy of the message to the file listed on
its command line. It is made obsolete by
The rcvtty program executes the named file with the message as its
standard input, and gives the resulting output to the terminal access
daemon for display on your terminal. If the terminal access daemon is
unavailable on your system, then rcvtty writes the output to your ter‐
minal, only if your terminal has world-writable permission. If no valid
file is specified, then rcvtty gives a one-line scan listing to the
terminal access daemon.
RESTRICTIONS
For compatibility with older versions of MH, if slocal cannot find the
user's file, it attempts to execute an old-style rcvmail hook in the
user's $HOME directory. Specifically, it first attempts to execute the
command:
.mh_receive file maildrop directory user
Failing that it attempts to execute:
$HOME/bin/rcvmail user file sender
If both of these fail, it gives up and write to the user's maildrop.
In addition, whenever a hook or process is invoked, file-descriptor
three (3) is set to the message in addition to the standard input.
Only two return codes are meaningful, others should be.
EXAMPLES
This section shows how slocal could be used.
In this example, line-by-line comments have been extracted from the
code to aid readability of the example. The line numbers would not nor‐
mally be in the code; they are there to help you. The code fragment
precedes the explanation:
───────────────────────────────────────────────────────────────
field pattern action result string
───────────────────────────────────────────────────────────────
(1) To mmdf2 file A mmdf2.log
(2) From mmdf pipe A err-message-
archive
(3) Sender uk-mmdf file ? mmdf2.log
(4) To Unix > A unix-news
(5) addr jpo=mmdf | A mmdf-redist
(6) addr jpo=ack | R resend -r
$(reply-to)
(7) From steve destroy A -
(8) default - > ? mailbox
(9) * - | R rcvalert
───────────────────────────────────────────────────────────────
File mail with mmdf2 in the To: line into file mmdf2.log. Messages
from mmdf are piped to the program err-message-archive. Take anything
with the address uk-mmdf in the Sender: field, and file it in
mmdf2.log, if it has not already been filed by line 1. Put messages
addressed to Unix in the file unix-news. If the address is jpo=mmdf,
pipe the message into mmdf-redist. If the address is jpo=ack, send an
acknowledgement copy back. Destroy anything from steve. Take anything
that is not matched yet and put it into mailbox. Always run rcvalert.
FILES
The system customization file. The system default file controlling
local delivery. The user-supplied alternative to the system default
file controlling local delivery.
SEE ALSOrcvstore(1)slocal(1)
