mh-sequence - sequence specification for nmh message system
most nmh commands
A sequence (or sequence set) is a symbolic name representing a message
or collection of messages. nmh has several internally defined
sequences, as well as allowing users to define their own sequences.
Message Specification and Pre-Defined Message Sequences
Most nmh commands accept a ‘msg’ or ‘msgs’ specification, where ‘msg’
indicates one message and ‘msgs’ indicates one or more messages. To
designate a message, you may use either its number (e.g., 1, 10, 234)
or one of these “reserved” message names:
first the first message in the folder
last the last message in the folder
cur the most recently accessed message
prev the message numerically preceding “cur”
next the message numerically following “cur”
In commands that take a ‘msg’ argument, the default is “cur”. As a
shorthand, “.” is equivalent to “cur”.
For example: In a folder containing five messages numbered 5, 10, 94,
177 and 325, “first” is 5 and “last” is 325. If “cur” is 94, then
“prev” is 10 and “next” is 177.
The word ‘msgs’ indicates that one or more messages may be specified.
Such a specification consists of one message designation or of several
message designations separated by spaces. A message designation
consists either of a message name as defined above, or a message range.
A message range is specified as “name1-name2” or “name:n”, where
‘name’, ‘name1’ and ‘name2’ are message names, and ‘n’ is an integer.
The specification “name1-name2” designates all currently existing
messages from ‘name1’ to ‘name2’ inclusive. The “reserved” message
name “all” is a shorthand for the message range “first-last”.
The specification “name:n” designates up to ‘n’ messages. These
messages start with ‘name’ if ‘name’ is a message number or one of the
reserved names “first” “cur”, or “next”, The messages end with ‘name’
if ‘name’ is “prev” or “last”. The interpretation of ‘n’ may be
overridden by preceding ‘n’ with a plus or minus sign; ‘+n’ always
means up to ‘n’ messages starting with ‘name’, and ‘-n’ always means up
to ‘n’ messages ending with ‘name’.
In commands which accept a ‘msgs’ argument, the default is either “cur”
or “all”, depending on which makes more sense for each command (see the
individual man pages for details). Repeated specifications of the same
message have the same effect as a single specification of the message.
There is also a special “reserved” message name “new” which is used by
the mhpath command.
User-Defined Message Sequences
In addition to the “reserved” (pre-defined) message names given above,
nmh supports user-defined sequence names. User-defined sequences allow
the nmh user a tremendous amount of power in dealing with groups of
messages in the same folder by allowing the user to bind a group of
messages to a meaningful symbolic name.
The name used to denote a message sequence must consist of an
alphabetic character followed by zero or more alphanumeric characters,
and can not be one of the “reserved” message names above. After
defining a sequence, it can be used wherever an nmh command expects a
‘msg’ or ‘msgs’ argument.
Some forms of message ranges are allowed with user-defined sequences.
The specification “name:n” may be used, and it designates up to the
first ‘n’ messages (or last ‘n’ messages for ‘-n’) which are elements
of the user-defined sequence ‘name’.
The specifications “name:next” and “name:prev” may also be used, and
they designate the next or previous message (relative to the current
message) which is an element of the user-defined sequence ‘name’. The
specifications “name:first” and “name:last” are equivalent to “name:1”
and “name:-1”, respectively. The specification “name:cur” is not
allowed (use just “cur” instead). The syntax of these message range
specifications is subject to change in the future.
User-defined sequence names are specific to each folder. They are
defined using the pick and mark commands.
Public and Private User-Defined Sequences
There are two varieties of user-defined sequences: public and private.
Public sequences of a folder are accessible to any nmh user that can
read that folder. They are kept in each folder in the file determined
by the “mh-sequences” profile entry (default is .mh_sequences).
Private sequences are accessible only to the nmh user that defined
those sequences and are kept in the user’s nmh context file.
In general, the commands that create sequences (such as pick and mark)
will create public sequences if the folder for which the sequences are
being defined is writable by the nmh user. For most commands, this can
be overridden by using the switches -public and -private. But if the
folder is read-only, or if the “mh-sequences” profile entry is defined
but empty, then private sequences will be created instead.
Nmh provides the ability to select all messages not elements of a user-
defined sequence. To do this, the user should define the entry
“Sequence-Negation” in the nmh profile file; its value may be any
string. This string is then used to preface an existing user-defined
sequence name. This specification then refers to those messages not
elements of the specified sequence name. For example, if the profile
then anytime an nmh command is given “notfoo” as a ‘msg’ or ‘msgs’
argument, it would substitute all messages that are not elements of the
Obviously, the user should beware of defining sequences with names that
begin with the value of the “Sequence-Negation” profile entry.
The Previous Sequence
Nmh provides the ability to remember the ‘msgs’ or ‘msg’ argument last
given to an nmh command. The entry “Previous-Sequence” should be
defined in the nmh profile; its value should be a sequence name or
multiple sequence names separated by spaces. If this entry is defined,
when when an nmh command finishes, it will define the sequence(s) named
in the value of this entry to be those messages that were specified to
the command. Hence, a profile entry of
directs any nmh command that accepts a ‘msg’ or ‘msgs’ argument to
define the sequence “pseq” as those messages when it finishes.
Note: there can be a performance penalty in using the
“Previous-Sequence” facility. If it is used, all nmh programs have to
write the sequence information to the .mh_sequences file for the folder
each time they run. If the “Previous-Sequence” profile entry is not
included, only pick and mark will write to the .mh_sequences file.
The Unseen Sequence
Finally, many users like to indicate which messages have not been
previously seen by them. The commands inc, rcvstore, show, mhshow, and
flist honor the profile entry “Unseen-Sequence” to support this
activity. This entry in the .mh_profile should be defined as one or
more sequence names separated by spaces. If there is a value for
“Unseen-Sequence” in the profile, then whenever new messages are placed
in a folder (using inc or rcvstore), the new messages will also be
added to all the sequences named in this profile entry. For example, a
profile entry of
directs inc to add new messages to the sequence “unseen”. Unlike the
behavior of the “Previous-Sequence” entry in the profile, however, the
sequence(s) will not be zeroed by inc.
Similarly, whenever show, mhshow, next, or prev displays a message,
that message will be removed from any sequences named by the
“Unseen-Sequence” entry in the profile.
$HOME/.mh_profile The user profile
<mh-dir>/context The user context
<folder>/.mh_sequences File for public sequences
mh-sequences: Name of file to store public sequences
Sequence-Negation: To designate messages not in a sequence
Previous-Sequence: The last message specification given
Unseen-Sequence: Those messages not yet seen by the user
flist(1), mark(1), pick(1), mh-profile(5)