4.3BSD-UWisc/man/catl/mhook.l
MHOOK(1) UNIX Programmer's Manual MHOOK(1)
NAME
mhook - MH receive-mail hooks
SYNOPSIS
$HOME/.maildelivery
/usr/misc/mh/lib/rcvdist [-form formfile]
[switches for _p_o_s_t_p_r_o_c] address ... [-help]
/usr/misc/mh/lib/rcvpack file [-help]
/usr/misc/mh/lib/rcvtty [command ...] [-help]
9 A receive-mail hook is a program that is run whenever you
receive a mail message. You do NOT invoke the hook your-
self, rather the hook is invoked on your behalf by _S_e_n_d_M_a_i_l,
when you include the line
"| /usr/misc/mh/lib/slocal -user $USER"
in your .forward file in your home directory.
The ._m_a_i_l_d_e_l_i_v_e_r_y file, which is an ordinary ASCII file,
controls how local delivery is performed. This file is read
by _s_l_o_c_a_l.
The format of each line in the ._m_a_i_l_d_e_l_i_v_e_r_y file is
field pattern action result string
where
field:
The name of a field that is to be searched for a pat-
tern. This is any field in the headers of the message
that might be present. In addition, the following spe-
cial fields are also defined:
_s_o_u_r_c_e: the out-of-band sender information
_a_d_d_r: the address that was used to cause delivery to
the recipient
_d_e_f_a_u_l_t: this matches _o_n_l_y if the message hasn't been
delivered yet
*: this always matches
pattern:
The sequence of characters to match in the specified
field. Matching is case-insensitive but not RE-based.
action:
The action to take to deliver the message. This is one
of
_f_i_l_e or >:
Append the message to the file named by string.
The standard maildrop delivery process is used. If
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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
which indicates the date and time that message was
appended to the file.
_p_i_p_e or |:
Pipe the message as the standard input to the com-
mand named by string, using the Bourne shell _s_h (1)
to interpret the string. Prior to giving the
string to the shell, it is expanded with the fol-
lowing 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: 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 envari-
ables $USER, $HOME, $SHELL are set appropriately,
and no other envariables exist.
The process is given a certain amount of time to
execute. If the process does not exit within this
limit, the process will be terminated with extreme
prejudice. 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 in
determining the success of the action. An exit
status of zero 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 _f_o_r_k_i_n_g. The
parent would return the appropriate value immedi-
ately, and the child could continue on, doing what-
ever it wanted for as long as it wanted. This
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approach is somewhat risky if the parent is going to
return an exit status of zero. If the parent is
going to return a non-zero exit status, then this
approach can lead to quicker delivery into your
maildrop.
_q_p_i_p_e or <_c_a_r_e_t>:
Similar to _p_i_p_e, but executes the command directly,
after built-in variable expansion, without assis-
tance from the shell.
_d_e_s_t_r_o_y:
This action always succeeds.
result:
Indicates how the action should be performed:
_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 mes-
sage is considered delivered.
The file is always read completely, so that several matches
can be made and several actions can be taken. The ._m_a_i_l_-
_d_e_l_i_v_e_r_y file must be owned either by the user or by root, and
must be writable only by the owner. If the ._m_a_i_l_d_e_l_i_v_e_r_y file
can not be found, or does not perform an action which delivers
the message, then the file /usr/misc/mh/lib/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
can not 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 ._m_a_i_l_d_e_l_i_v_e_r_y file are separated by
white-space or comma. 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 preceeding it with a backslash.
To summarize, here's an example:
#_f_i_e_l_d _p_a_t_t_e_r_n _a_c_t_i_o_n _r_e_s_u_l_t _s_t_r_i_n_g
# lines starting with a '#' are ignored, as are blank lines
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#
# file mail with mmdf2 in the "To:" line into file mmdf2.log
To mmdf2 file A mmdf2.log
# Messages from mmdf pipe to the program err-message-archive
From mmdf pipe A err-message-archive
# Anything with the "Sender:" address "uk-mmdf-workers"
# file in mmdf2.log if not filed already
Sender uk-mmdf-workers file ? mmdf2.log
# "To:" unix - put in file unix-news
To Unix > A unix-news
# if the address is jpo=mmdf - pipe into mmdf-redist
addr jpo=mmdf | A mmdf-redist
# if the address is jpo=ack - send an acknowledgement copy back
addr jpo=ack | R "resend -r $(reply-to)"
# anything from steve - destroy!
From steve destroy A -
# anything not matched yet - put into mailbox
default - > ? mailbox
# always run rcvalert
* - | R rcvalert
Four programs are currently standardly available, _r_c_v_d_i_s_t
(redistribute incoming messages to additional recipients),
_r_c_v_p_a_c_k (save incoming messages in a _p_a_c_k_f'd file), and _r_c_v_t_t_y
(notify user of incoming messages). The fourth program,
_r_c_v_s_t_o_r_e (1) is described separately. They all reside in the
/_u_s_r/_m_i_s_c/_m_h/_l_i_b/ directory.
The _r_c_v_d_i_s_t program will resend a copy of the message to all
of the addresses listed on its command line. It uses the for-
mat string facility described in _m_h-_f_o_r_m_a_t (5).
The _r_c_v_p_a_c_k program will append a copy of the message to the
file listed on its command line. Its use is obsoleted by the
._m_a_i_l_d_e_l_i_v_e_r_y.
The _r_c_v_t_t_y program executes the named file with the message as
its standard input, and gives the resulting output to the ter-
minal access daemon for display on your terminal. If the ter-
minal access daemon is unavailable on your system, then _r_c_v_t_t_y
will write the output to your terminal if, and only if, your
terminal has "world-writable" permission. If no file is
specified, or is bogus, etc., then the _r_c_v_t_t_y program will
give a one-line scan listing to the terminal access daemon.
FILES
/usr/misc/mh/lib/mtstailor tailor file
$HOME/.maildelivery The file controlling local delivery
/usr/misc/mh/lib/maildelivery Rather than the standard file
SEE ALSO
rcvstore (1)
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CONTEXT
None
HISTORY
For compatibility with older versions of _M_H, if _s_l_o_c_a_l can't
find the user's ._m_a_i_l_d_e_l_i_v_e_r_y file, it will attempt to exe-
cute an old-style rcvmail hook in the user's $HOME direc-
tory. In particular, it will first attempt to execute
.mh_receive file maildrop directory user
failing that it will attempt to execute
$HOME/bin/rcvmail user file sender
before giving up and writing 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.
BUGS
Only two return codes are meaningful, others should be.
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