slocal(1) General Commands Manual slocal(1)
NAME
slocal - MH receive-mail hooks
SYNOPSIS
slocal $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
message 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 recipient
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 Regular
Expression-based. The action to take to deliver the message. 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 directory is
the recipient's directory; the umask is 0077; the process has no /dev/tty; the standard input is set to the message; the standard
output and diagnostic output are set to /dev/null; all other file-descriptors are closed; the environment 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 suc-
ceeded. 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 cannot 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 suc-
ceeded, 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
message, 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 facility
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
terminal, 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-ar-
chive
(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 ALSO
rcvstore(1)
slocal(1)