.TH SCAN %manext1% 2020-02-17 "%nmhversion%"
.
.\" %nmhwarning%
.
.SH NAME
scan \- produce a summary listing of nmh messages
.SH SYNOPSIS
.HP 5
.na
.B scan
.RB [ \-help ]
.RB [ \-version ]
.RI [ +folder ]
.RI [ msgs ]
.RB [ \-clear " | " \-noclear ]
.RB [ \-form
.IR formatfile ]
.RB [ \-format
.IR string ]
.RB [ \-header " | " \-noheader ]
.RB [ \-width
.IR columns ]
.RB [ \-reverse " | " \-noreverse ]
.RB [ \-file
.IR filename ]
.ad
.SH DESCRIPTION
.B scan
produces a one-line-per-message listing of the specified
folder or messages.  Each
.B scan
line contains the message number
(name), the date, the \*(lqFrom:\*(rq field, the \*(lqSubject\*(rq field,
and, if room allows, some of the body of the message.  For example:
.PP
.RS 5
.nf
.ta \w'15+- 'u +\w'07/\|05x 'u +\w'Dcrocker  'u
15+	10/\|05 crocker	nned\0\0<<Last week I asked some of
16\-	10/\|05 crocker	message id format\0\0<<I recommend
18	10/\|06 brien	Re: Exit status from mkdir
19	10/\|07*brien	\*(lqscan\*(rq listing format in nmh
.fi
.RE
.PP
The `+' on message 15 indicates that it is the current message.
.PP
The `\-' on message 16 indicates that it has been replied to, as indicated
by a \*(lqReplied:\*(rq component (produced by the
.B \-annotate
switch
to the
.B repl
command).
.PP
The `*' on message 19 indicates that no \*(lqDate:\*(rq header was
present.  The time of last modification of the message is given instead.
.PP
If there is sufficient room left on the
.B scan
line after the
subject, the line will be filled with text from the body, preceded by
\*(lq<<\*(rq, and terminated by \*(lq>>\*(rq if the body is sufficiently short.
.B scan
actually reads each of the specified messages and parses them to extract
the desired fields.  During parsing, appropriate error messages will be
produced if there are format errors in any of the messages.
.PP
By default,
.B scan
will decode RFC 2047 (MIME) encoding in
these scan listings.
.B scan
will only decode these fields if your
terminal can natively display the character set used in the encoding.
You should set the appropriate
.IR locale (1)
environment variables to your native
character set, if it is not US-ASCII.  See
.IR locale (1)
for more details on the appropriate environment variables.
.PP
The switch
.BR \-reverse ,
makes
.B scan
list the messages in reverse
order.
.PP
The
.B \-file
.I filename
switch allows the user to obtain a
.B scan
listing of a mail drop.
This listing
includes every message in the mail drop (you can't scan individual messages).
The switch
.B \-reverse
is ignored with this option.
If
.I filename
is a file, it can be in
.B mbox
or
.B MMDF
format, as produced by
.BR packf .
If
.I filename
is a directory, it is considered to be in
.B Maildir
format.
.PP
The switch
.B \-width
.I columns
may be used to specify the width of
the scan line.  The default is to use the width of the terminal.
.PP
The
.B \-header
switch produces a header line prior to the
.B scan
listing.  Currently, the name of the folder and the current date and
time are output (see the
.B HISTORY
section for more information).
.PP
If the
.B \-clear
switch is used and
.BR scan 's
output is directed
to a terminal, then
.B scan
will consult the environment variables
.B $TERM
and
.B $TERMCAP
to determine your terminal type in order
to find out how to clear the screen prior to exiting.  If the
.B \-clear
switch is used and
.BR scan 's
output is not directed to a terminal
(e.g., a pipe or a file), then
.B scan
will send a formfeed prior
to exiting.
.PP
For example, the command:
.PP
.RS 5
(scan \-clear \-header; show all \-show pr \-f) | lpr
.RE
.PP
produces a scan listing of the current folder, followed by a formfeed,
followed by a formatted listing of all messages in the folder, one
per page.  Omitting
.RB \*(lq "\-show\ pr\ \-f" \*(rq
will cause the messages to be
concatenated, separated by a one-line header and two blank lines.
.PP
To override the output format used by
.BR scan ,
the
.B \-format
.I string
or
.B \-form
.I file
switches are used.  This permits individual fields of
the scan listing to be extracted with ease.  The string is simply a format
string and the file is simply a format file.  See
.IR mh\-format (5)
for the details.
.PP
In addition to the standard
.IR mh\-format (5)
escapes,
.B scan
also recognizes the following additional
.I component
escapes:
.PP
.RS 5
.nf
.ta \w'Dtimenow  'u +\w'Returns  'u
.I "Escape	Returns	Description"
body	string	the (compressed) first part of the body
dtimenow	date	the current date
folder	string	the name of the current folder
.fi
.RE
.PP
.RB { body }
returns a string without MIME decoding,
i.e.\& the MIME boundary separator may be the first text shown.
.PP
If no date header is present in the message, the
.I function
escapes
which operate on
.RB { date }
will return values for the date of last
modification of the message file itself.  This feature is handy for
scanning a draft folder, as message drafts usually aren't allowed
to have dates in them.
.PP
The
.B %nmhetcdir%
directory contains several format files as examples of customized
.B scan
output.
.PP
.B scan
will update the
.B nmh
context prior to starting the listing,
so interrupting a long
.B scan
listing preserves the new context.
.B nmh
purists hate this idea.
.SH FILES
.fc ^ ~
.nf
.ta \w'%nmhetcdir%/ExtraBigFileName  'u
^$HOME/.mh_profile~^The user profile
.fi
.SH "PROFILE COMPONENTS"
.fc ^ ~
.nf
.ta 2.4i
.ta \w'ExtraBigProfileName  'u
^Path:~^To determine the user's nmh directory
^Alternate\-Mailboxes:~^To determine the user's mailboxes
^Current\-Folder:~^To find the default current folder
.fi
.SH "SEE ALSO"
.IR pick (1),
.IR show (1),
.IR mh\-format (5)
.SH DEFAULTS
.nf
.RB ` +folder "' defaults to the current folder"
.RB ` msgs "' defaults to all"
.RB ` \-format "' defaulted as described above"
.RB ` \-noheader '
.RB ` \-width "' defaulted to the width of the terminal"
.fi
.SH CONTEXT
If a folder is given, it will become the current folder.
.SH HISTORY
Prior to using the format string mechanism,
.B \-header
used to generate
a heading saying what each column in the listing was.  Format strings
prevent this from happening.
.SH BUGS
The value of each
.I component
escape is set by
.B scan
to the
contents of the first message header
.B scan
encounters with the
corresponding component name; any following headers with the same
component name are ignored.