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
.forward file in your home directory: "| /usr/lib/mh/slocal -user user-
name"
The .maildelivery 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 .maildelivery file is: field pattern ac-
tion result string
These components are explained below:
field: 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 re-
cipient
default: this matches only if the message has not been deliv-
ered yet
*: this always matches
pattern: The sequence of characters to match in the specified field.
Matching is case-insensitive but not Regular Expression-
based.
action: The action to take to deliver the message. This is one of
the following:
file or >:
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 writ-
ing to the file, a new field is added:
Delivery-Date: <date>
This field indicates the date and time at which the message
was appended to the file.
pipe or | :
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 ex-
panded 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 mes-
sage
$(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 di-
rectory 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 envi-
ronment variables $USER, $HOME, and $SHELL are set appropri-
ately; 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 termi-
nated. The amount of time is calculated as ((size x 60) +
300) seconds, where size is the number of bytes in the mes-
sage.
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 termi-
nation) 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 ap-
proach should only be used if you do not care about the out-
come 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 mail-
drop.
qpipe or ^ :
This is similar to pipe, but executes the command directly,
after built-in variable expansion, without assistance from
the shell.
destroy:
This action always succeeds.
result: Indicates how the action should be performed. The following
values are valid:
A:
Perform the action. If the action succeeded, then the mes-
sage is considered delivered.
R:
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 deliv-
ered. If the action succeeded, then the message is consid-
ered delivered.
The file is always read completely, so that several matches can be made
and several actions can be taken. The .maildelivery file must be owned
either by the user or by root, and must be writable only by the owner.
If the .maildelivery file cannot be found, or does not perform an ac-
tion 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 .maildelivery 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 dou-
ble 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 ad-
dresses 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 .maildelivery.
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 .maildelivery 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
normally be in the code; they are there to help you. The code fragment
precedes the explanation:
tab(@); l l l l l l. @field@pattern@action@result@string
(1)@To@mmdf2@file@
[email protected] (2)@From@mmdf@pipe@A@err-message-archive
(3)@Sender@uk-mmdf@file@
[email protected] (4)@To@Unix@>@A@unix-news
(5)@addr@jpo=mmdf@|@A@mmdf-redist (6)@addr@jpo=ack@|@R@resend -r $(re-
ply-to) (7)@From@steve@destroy@A@- (8)@default@-@>@?@mailbox
(9)@*@-@|@R@rcvalert
Line 1: File mail with mmdf2 in the To: line into file mmdf2.log.
Line 2: Messages from mmdf are piped to the program err-message-
archive.
Line 3: 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.
Line 4: Put messages addressed to Unix in the file unix-news.
Line 5: If the address is jpo=mmdf, pipe the message into mmdf-re-
dist.
Line 6: If the address is jpo=ack, send an acknowledgement copy back.
Line 7: Destroy anything from steve.
Line 8: Take anything that is not matched yet and put it into mail-
box.
Line 9: Always run rcvalert.
FILES
/usr/lib/mh/mtstailor
The system customization file.
/usr/lib/mh/maildelivery
The system default file controlling local delivery.
$HOME/.maildelivery
The user-supplied alternative to the system default file con-
trolling local delivery.
RELATED INFORMATION
rcvstore(1) delim off
slocal(1)