Ubuntu Manpage: mh-sequence - sequence specification for nmh message system

NAME

       mh-sequence - sequence specification for nmh message system

SYNOPSIS

       most nmh commands

DESCRIPTION

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:

Name Description
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.

Sequence Negation
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 entry is:

Sequence-Negation: not

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 sequence “foo”.

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

Previous-Sequence: pseq

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

Unseen-Sequence: unseen

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.

FILES

       $HOME/.mh_profile          The user profile
       <mh-dir>/context           The user context
       <folder>/.mh_sequences     File for public sequences

PROFILE COMPONENTS

       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

DEFAULTS