slocal(1mh) slocal(1mh)
Name
slocal - MH receive-mail hooks
Syntax
slocal $HOME/.maildelivery [ -form formfile ] [ switches for ] 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 when you include the following line in your file in your home directory:
| /usr/lib/mh/slocal -user $USER
The file, which is an ordinary ASCII file, controls how local delivery is performed. This file is read by
The format of each line in the file is:
field pattern action 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 recipient
default: this matches only if the message has not been delivered 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 writing 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, 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 the standard input is set to the message; the standard output
and diagnostic output are set to 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
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 appro-
priate 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 However, if the parent is going to return a non-zero exit status, then this approach can lead to quicker delivery
into your maildrop.
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 message 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 delivered. If the action succeeded, then the message is considered deliv-
ered.
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 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, is per-
formed.
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: redistributes incoming messages to additional recipients; saves incoming messages in a file; and
notifies the user of incoming messages. The fourth program, is described in the reference page. They all reside in the directory.
The 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
The program appends a copy of the message to the file listed on its command line. It is made obsolete by
The 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 writes the output to your terminal, only
if your terminal has world-writable permission. If no valid file is specified, then gives a one-line scan listing to the terminal access
daemon.
Restrictions
For compatibility with older versions of MH, if cannot find the user's file, it attempts to execute an old-style hook in the user's direc-
tory. 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 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:
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
Line 1: File mail with mmdf2 in the To: line into file
Line 2: Messages from mmdf are piped to the program
Line 3: Take anything with the address uk-mmdf in the Sender: field, and file it in if it has not already been filed by line 1.
Line 4: Put messages addressed to Unix in the file
Line 5: If the address is jpo=mmdf, pipe the message into
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 mailbox.
Line 9: Always run
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(1mh)
slocal(1mh)