-.\"
+.TH MH-FORMAT %manext5% 2015-01-10 "%nmhversion%"
+.
.\" %nmhwarning%
-.\" $Id$
-.\"
-.\" include the -mh macro file
-.so %etcdir%/tmac.h
-.\"
-.TH MH-FORMAT %manext5% MH.6.8 [%nmhversion%]
+.
.SH NAME
-mh-format \- format file for nmh message system
-.SH SYNOPSIS
-.in +.5i
-.ti -.5i
-some \fInmh\fR commands
-.in -.5i
+mh-format \- formatting language for nmh message system
.SH DESCRIPTION
-Several \fInmh\fR commands utilize either a \fIformat\fR string or a
-\fIformat\fR file during their execution. For example, \fIscan\fR\0(1)
-uses a format string which directs it how to generate the scan listing
-for each message; \fIrepl\fR\0(1) uses a format file which directs it
-how to generate the reply to a message, and so on.
-
-Format strings are designed to be efficiently parsed by \fInmh\fR
-which means they are not necessarily simple to write and understand.
-This means that novice, casual, or even advanced users of \fInmh\fR
-should not have to deal with them.
-
-There are a few alternate scan listing formats available
-in %etcdir%/scan.time, %etcdir%/scan.size, and %etcdir%/scan.timely.
-Look in %etcdir% for other \fIscan\fR and \fIrepl\fR format files which
-may have been written at your site.
-
-It suffices to have your local \fInmh\fR expert actually write new format
-commands or modify existing ones. This manual section explains how to
-do that. Note: familiarity with the C \fIprintf\fR routine is assumed.
-
-A format string consists of ordinary text, and special multi-character
-\fIescape\fR sequences which begin with `%'. When specifying a format
-string, the usual C backslash characters are honored: `\\b', `\\f',
-`\\n', `\\r', and `\\t'. Continuation lines in format files end with
-`\\' followed by the newline character.
-
+Several
+.B nmh
+commands utilize either a
+.I format
+string or a
+.I format
+file during their execution. For example,
+.B scan
+uses a format string to generate its listing of messages;
+.B repl
+uses a format file to generate message replies, and so on.
+.PP
+There are a number of scan listing formats available,
+including
+.IR nmh/etc/scan.time ,
+.IR nmh/etc/scan.size ,
+and
+.IR nmh/etc/scan.timely .
+Look in
+.I %nmhetcdir%
+for other
+.B scan
+and
+.B repl
+format files which may have been written at your site.
+.PP
+You can have your local
+.B nmh
+expert write new format commands or modify existing ones,
+or you can try your hand at it yourself.
+This manual section explains how to do that.
+Note: some familiarity with the C
+.B printf
+routine is assumed.
+.PP
+A format string consists of ordinary text combined with special,
+multi-character, escape sequences which begin with `%'.
+When specifying a format string, the usual C backslash characters
+are honored: `\\b', `\\f', `\\n', `\\r', and `\\t'.
+Continuation lines in format files end with `\\' followed by the
+newline character. A literal `%' can be inserted into a format
+file by using the sequence `%%'.
.\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
-There are three types of \fIescape\fR sequences: header
-\fIcomponents\fR, built-in \fIfunctions\fR, and flow \fIcontrol\fR.
-
-A \fIcomponent\fR escape is specified as `%{\fIcomponent\fR\^}', and
-exists for each header found in the message being processed. For example
-`%{date}' refers to the \*(lqDate:\*(rq field of the appropriate message.
-All component escapes have a string value. Normally, component values are
+.SS SYNTAX
+Format strings are built around
+.IR "escape sequences" .
+There are three types of escape sequence: header
+.IR components ,
+built-in
+.IR functions ,
+and flow
+.IR control .
+Comments may be inserted in most places where a function argument is
+not expected. A comment begins with `%;' and ends with a (non-escaped)
+newline.
+.SS "Component escapes"
+A
+.I component
+escape is specified as
+.RI `%{ component }',
+and
+exists for each header in the message being processed. For example,
+.RI `%{ date }'
+refers to the \*(lqDate:\*(rq field of the message.
+All component escapes have a string value. Such values are usually
compressed by converting any control characters (tab and newline included)
-to spaces, then eliding any leading or multiple spaces. However, commands
-may give different interpretations to some component escapes; be sure
-to refer to each command's manual entry for complete details.
-
-A \fIfunction\fR escape is specified as `%(\fIfunction\fR\^)'.
-All functions are built-in, and most have a string or numeric value.
-
-.ne 12
-.Uh "Control-flow escapes"
-A \fIcontrol\fR escape is one of: `%<', `%?', `%|', or `%>'.
-These are combined into the conditional execution construct:
-.sp
+to spaces, then eliding any leading or multiple spaces. Some commands,
+however, may interpret some component escapes differently; be sure to
+refer to each command's manual entry for details.
+Some commands (such as
+.IR ap (8)
+and
+.IR mhl (1) )
+use a special component
+.RI `%{ text }'
+to refer to the text being processed; see their respective man pages for
+details and examples.
+.SS "Function escapes"
+A
+.I function
+escape is specified as
+.RI `%( function )'.
+All functions are built-in, and most have a string or integer value.
+A function escape may take an
+.IR argument .
+The argument follows the function escape (and any separating
+whitespace is discarded) as in the following example:
+.PP
+.RS 5
.nf
- %<condition
- \fIformat text 1\fP
- %?condition2
- \fIformat text 2\fP
- %?condition3
- \fIformat text 3\fP
- \.\.\.
- %|
- \fIformat text N\fP
- %>
+.RI %( function " " argument )
.fi
-.sp
-Extra white space is shown here only for clarity. These
-constructs may be nested without ambiguity. They form a general
-\fBif\-elseif\-else\-endif\fP block where only one of the \fIformat
-text\fP segments is interpreted.
-
-The `%<' and `%?' control escapes causes a condition to be evaluated.
-This condition
-may be either a \fIcomponent\fP or a \fIfunction\fP.
-The four constructs have the following syntax:
-.sp 1
+.RE
+.PP
+In addition to literal numbers or strings, the argument to a
+function escape can be another function, or a component,
+or a control escape. When the argument is a function or a
+component, the argument is specified without a leading `%'.
+When the argument is a control escape, it is specified
+with a leading `%'.
+.SS "Control escapes"
+A
+.I control
+escape is one of: `%<', `%?', `%|', or `%>'.
+These are combined into the conditional execution construct:
+.PP
+.RS 5
.nf
- %<{component}
- %<(function)
- %?{component}
- %?(function)
+.RI "%< " condition " " "format-text"
+.RI "%? " condition " " "format-text"
+ ...
+.RI "%| " "format-text"
+%>
.fi
-.sp
-These control escapes test whether the function or component value is
-non-zero (for integer-valued escapes), or non-empty (for string-valued
-escapes).
-
-If this test evaulates true, then the format text up to the next
-corresponding control escape (one of `%|', `%?', or `%>') is interpreted
-normally. Next, all format text (if any) up to the corresponding `%>'
-control escape is skipped. The `%>' control escape is not interpreted;
-normal interpretation resumes after the `%>' escape.
-
-If the test evaluates false, however, then the format text up to
-the next corresponding control escape (again, one of `%|', `%?', or
-`%>') is skipped, instead of being interpreted. If the control escape
-encountered was `%?', then the condition associated with that control
-escape is evaluated, and interpretation proceeds after that test as
-described in the previous paragraph. If the control escape encountered
-was `%|', then the format text up to the corresponding `%>' escape is
-interpreted normally. As above, the `%>' escape is not interpreted and
-normal interpretation resumes after the `%>' escape.
-
-The `%?' control escape and its following format text is optional, and may
-be included zero or more times. The `%|' control escape and its following
-format text is also optional, and may be included zero or one times.
-
-.Uh "Function escapes"
-.ne 10
-Most functions expect an argument of a particular type:
-.sp 1
+.RE
+.PP
+(Extra white space is shown here only for clarity.)
+These constructs, which may be nested without ambiguity, form a general
+.B if-elseif-else-endif
+block where only one of the format-texts is interpreted. In other
+words, `%<' is like the "if", `%?' is like the "elseif", `%|' is like
+"else", and `%>' is like "endif".
+.PP
+A `%<' or `%?' control escape causes its condition to be evaluated.
+This condition is a
+.I component
+or
+.IR function .
+For components and functions whose value is an integer, the condition is true
+if it is non-zero, and false if zero.
+For components and functions whose value is a string, the condition is true
+it is a non-empty string, and false if an empty string.
+.PP
+The `%?' control escape is optional, and can be used multiple times
+in a conditional block. The `%|' control escape is also optional,
+but may only be used once.
+.SS "Function escapes"
+Functions expecting an argument generally require an argument of a
+particular type. In addition to the integer and string types,
+these include:
+.PP
+.RS 5
.nf
.ta +\w'Argument 'u +\w'An optional component, 'u
-\fIArgument\fR \fIDescription\fR \fIExample Syntax\fR
-literal A literal number, %(\fIfunc\fR 1234)
- or string %(\fIfunc\fR text string)
-comp Any header component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
+.I "Argument Description Example Syntax"
+literal A literal number %(\fIfunc\fR 1234)
+ or string %(\fIfunc\fR text string)
+comp Any component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
date A date component %(\fIfunc\fR\^{\fIdate\fR\^})
addr An address component %(\fIfunc\fR\^{\fIfrom\fR\^})
-expr An optional component, %(\fIfunc\fR\^(\fIfunc2\fR\^))
- function or control, %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
- perhaps nested %(\fIfunc\fR\^(\fIfunc2\fR\^{\fIcomp\fR\^}))
-.re
+expr Nothing %(\fIfunc\fR)
+ or a subexpression %(\fIfunc\fR\^(\fIfunc2\fR\^))
+ or control escape %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
.fi
-
-The types \fIdate\fR and \fIaddr\fR have the same syntax as \fIcomp\fR,
-but require that the header component be a date string, or address
+.RE
+.PP
+The
+.I date
+and
+.I addr
+types have the same syntax as the component type,
+.IR comp ,
+but require a header component which is a date, or address,
string, respectively.
-
-All arguments except those of type \fIexpr\fR are required. For the
-\fIexpr\fR argument type, the leading `%' must be omitted for component
-and function escape arguments, and must be present (with a leading space)
-for control escape arguments.
-
-The evaluation of format strings is based on a simple virtual machine
-with an integer register \fInum\fR, and a text string register \fIstr\fR.
-When a function escape is processed, if it accepts an optional \fIexpr\fR
-argument which is not present, it reads the current value of either
-\fInum\fR or \fIstr\fR as appropriate.
-
-.Uh "Return values"
-Component escapes write the value of their message header in \fIstr\fR.
-Function escapes write their return value in \fInum\fR for functions
-returning \fIinteger\fR or \fIboolean\fR values, and in \fIstr\fR for
-functions returning string values. (The \fIboolean\fR type is a subset
-of integers with usual values 0=false and 1=true.) Control escapes
-return a \fIboolean\fP value, and set \fInum\fP.
-
+.PP
+Most arguments not of type
+.I expr
+are required.
+When escapes are nested (via expr arguments), evaluation is done
+from innermost to outermost. As noted above, for the
+.I expr
+argument type, functions and components are written without a
+leading `%'.
+Control escape arguments must use a leading `%', preceded by a space.
+.PP
+For example,
+.PP
+.RS 5
+.nf
+%<(mymbox{from}) To: %{to}%>
+.fi
+.RE
+.PP
+writes the value of the header component \*(lqFrom:\*(rq to the
+internal register named str; then (\fImymbox\fR\^) reads str and
+writes its result to the internal register named
+.IR num ;
+then the control escape, `%<', evaluates
+.IR num .
+If
+.I num
+is non-zero, the string \*(lqTo:\*(rq is printed followed by the
+value of the header component \*(lqTo:\*(rq.
+.SS Evaluation
+The evaluation of format strings is performed
+by a small virtual machine.
+The machine is capable of evaluating nested expressions
+(as described above) and, in addition, has an integer register
+.IR num ,
+and a text string register
+.IR str .
+When a function escape that accepts an optional argument is processed,
+and the argument is not present, the current value of either
+.I num
+or
+.I str
+is substituted as the argument: the register used depends on the function,
+as listed below.
+.PP
+Component escapes write the value of their message header in
+.IR str .
+Function escapes write their return value in
+.I num
+for functions returning integer or boolean values, and in
+.I str
+for functions returning string values. (The boolean type is a subset
+of integers, with usual values 0=false and 1=true.) Control escapes
+return a boolean value, setting
+.I num
+to 1 if the last explicit condition
+evaluated by a `%<' or `%?' control escape succeeded, and 0 otherwise.
+.PP
All component escapes, and those function escapes which return an
-\fIinteger\fR or \fIstring\fR value, pass this value back to their caller
-in addition to setting \fIstr\fR or \fInum\fR. These escapes will print
-out this value unless called as part of an argument to another escape
-sequence. Escapes which return a \fIboolean\fR value do pass this value
-back to their caller in \fInum\fP, but will never print out the value.
-
+integer or string value, evaluate to their value as well as setting
+.I str
+or
+.IR num .
+Outermost escape expressions in these forms will print
+their value, but outermost escapes which return a boolean value
+do not result in printed output.
+.SS Functions
+The function escapes may be roughly grouped into a few categories.
+.PP
+.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-\fIFunction\fR \fIArgument\fR \fIReturn\fR \fIDescription\fR
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Return Description"
msg integer message number
-cur integer message is current
-unseen integer message is unseen
+cur integer message is current (0 or 1)
+unseen integer message is unseen (0 or 1)
size integer size of message
strlen integer length of \fIstr\fR
-width integer output buffer size in bytes
+width integer column width of terminal
charleft integer bytes left in output buffer
-timenow integer seconds since the UNIX epoch
-me string the user's mailbox
+timenow integer seconds since the Unix epoch
+me string the user's mailbox (username)
+myhost string the user's local hostname
+myname string the user's name
+localmbox string the complete local mailbox
eq literal boolean \fInum\fR == \fIarg\fR
ne literal boolean \fInum\fR != \fIarg\fR
gt literal boolean \fInum\fR > \fIarg\fR
amatch literal boolean \fIstr\fR starts with \fIarg\fR
plus literal integer \fIarg\fR plus \fInum\fR
minus literal integer \fIarg\fR minus \fInum\fR
+multiply literal integer \fInum\fR multiplied by \fIarg\fR
divide literal integer \fInum\fR divided by \fIarg\fR
modulo literal integer \fInum\fR modulo \fIarg\fR
-num literal integer Set \fInum\fR to \fIarg\fR
-lit literal string Set \fIstr\fR to \fIarg\fR
+num literal integer Set \fInum\fR to \fIarg\fR.
+num integer Set \fInum\fR to zero.
+lit literal string Set \fIstr\fR to \fIarg\fR.
+lit string Clear \fIstr\fR.
getenv literal string Set \fIstr\fR to environment value of \fIarg\fR
-profile literal string Set \fIstr\fR to profile component \fIarg\fR value
+profile literal string Set \fIstr\fR to profile component \fIarg\fR
+ value
.\" dat literal int return value of dat[arg]
nonzero expr boolean \fInum\fR is non-zero
zero expr boolean \fInum\fR is zero
comp comp string Set \fIstr\fR to component text
compval comp integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
.\" compflag comp integer Set \fInum\fR to component flags bits (internal)
-.\" decodecomp comp string Set \fIstr\fR to RFC-2047 decoded component text
-decode expr string decode \fIstr\fR as RFC-2047 component
-trim expr trim trailing white-space from \fIstr\fR
+.\" decodecomp comp string Set \fIstr\fR to RFC 2047 decoded component text
+decode expr string decode \fIstr\fR as RFC 2047 (MIME-encoded)
+ component
+unquote expr string remove RFC 2822 quotes from \fIstr\fR
+trim expr trim trailing whitespace from \fIstr\fR
+kilo expr string express in SI units: 15.9K, 2.3M, etc.
+ %(kilo) scales by factors of 1000,
+kibi expr string express in IEC units: 15.5Ki, 2.2Mi.
+ %(kibi) scales by factors of 1024.
putstr expr print \fIstr\fR
putstrf expr print \fIstr\fR in a fixed width
putnum expr print \fInum\fR
putnumf expr print \fInum\fR in a fixed width
-.\" addtoseq literal add msg to sequence (LBL option)
-.re
+putlit expr print \fIstr\fR without space compression
+zputlit expr print \fIstr\fR without space compression;
+ \fIstr\fR must occupy no width on display
+bold string set terminal bold mode
+underline string set terminal underlined mode
+standout string set terminal standout mode
+resetterm string reset all terminal attributes
+hascolor boolean terminal supports color
+fgcolor literal string set terminal foreground color
+bgcolor literal string set terminal background color
+formataddr expr append \fIarg\fR to \fIstr\fR as a
+ (comma separated) address list
+concataddr expr append \fIarg\fR to \fIstr\fR as a
+ (comma separated) address list,
+ including duplicates,
+ see Special Handling
+putaddr literal print \fIstr\fR address list with
+ \fIarg\fR as optional label;
+ get line width from \fInum\fR
+.fi
+.RE
+.PP
+The (\fIme\fR\^) function returns the username of the current user.
+The (\fImyhost\fR\^) function returns the
+.B localname
+entry in
+.IR mts.conf ,
+or the local hostname if
+.B localname
+is not configured. The (\fImyname\fR\^) function will return the value of
+the
+.B SIGNATURE
+environment variable if set, otherwise it will return the passwd GECOS field
+(truncated at the first comma if it contains one) for
+the current user. The (\fIlocalmbox\fR\^) function will return the complete
+form of the local mailbox, suitable for use in a \*(lqFrom\*(rq header.
+It will return the
+.RI \*(lq Local-Mailbox \*(rq
+profile entry if there is one; if not, it will be equivalent to:
+.PP
+.RS 5
+.nf
+%(myname) <%(me)@%(myhost)>
.fi
-
-These functions require a date component as an argument:
-.sp 1
+.RE
+.PP
+The following functions require a date component as an argument:
+.PP
+.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-\fIFunction\fR \fIArgument\fR \fIReturn\fR \fIDescription\fR
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Return Description"
sec date integer seconds of the minute
min date integer minutes of the hour
hour date integer hours of the day (0-23)
day date string day of the week (abbrev.)
weekday date string day of the week
sday date integer day of the week known?
- (0=implicit,\-1=unknown)
+ (1=explicit,0=implicit,\-1=unknown)
mday date integer day of the month
yday date integer day of the year
mon date integer month of the year
month date string month of the year (abbrev.)
lmonth date string month of the year
year date integer year (may be > 100)
-zone date integer timezone in hours
+zone date integer timezone in minutes
tzone date string timezone string
szone date integer timezone explicit?
- (0=implicit,\-1=unknown)
+ (1=explicit,0=implicit,\-1=unknown)
date2local date coerce date to local timezone
date2gmt date coerce date to GMT
-dst date integer daylight savings in effect?
-clock date integer seconds since the UNIX epoch
+dst date integer daylight savings in effect? (0 or 1)
+clock date integer seconds since the Unix epoch
rclock date integer seconds prior to current time
-tws date string official 822 rendering
+tws date string official RFC 822 rendering
pretty date string user-friendly rendering
-nodate date integer \fIstr\fR not a date string
-.re
+nodate date integer returns 1 if date is invalid
.fi
-
-.ne 12
-These functions require an address component as an argument.
-The return value of functions noted with `*' pertain only to
+.RE
+.PP
+The following functions require an address component as an argument.
+The return value of functions noted with `*' is computed from
the first address present in the header component.
-.sp 1
+.PP
+.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-\fIFunction\fR \fIArgument\fR \fIReturn\fR \fIDescription\fR
-proper addr string official 822 rendering
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Return Description"
+proper addr string official RFC 822 rendering
friendly addr string user-friendly rendering
addr addr string mbox@host or host!mbox rendering*
pers addr string the personal name*
note addr string commentary text*
mbox addr string the local mailbox*
-mymbox addr integer the user's addresses? (0=no,1=yes)
+mymbox addr integer list has the user's address? (0 or 1)
+getmymbox addr string the user's (first) address,
+ with personal name
+getmyaddr addr string the user's (first) address,
+ without personal name
host addr string the host domain*
-nohost addr integer no host was present*
+nohost addr integer no host was present (0 or 1)*
type addr integer host type* (0=local,1=network,
\-1=uucp,2=unknown)
path addr string any leading host route*
-ingrp addr integer address was inside a group*
+ingrp addr integer address was inside a group (0 or 1)*
gname addr string name of group*
-formataddr expr append \fIarg\fR to \fIstr\fR as a
- (comma separated) address list
-putaddr literal print \fIstr\fR address list with
- \fIarg\fR as optional label;
- get line width from \fInum\fR
-.re
.fi
-
-When escapes are nested, evaluation is done from inner-most to outer-most.
-The outer-most escape must begin with `%'; the inner escapes must not.
-For example,
-
-.ti +.5i
-%<(mymbox{from}) To: %{to}%>
-
-writes the value of the header component \*(lqFrom:\*(rq to \fIstr\fR\^;
-then (\fImymbox\fR\^) reads \fIstr\fR and writes its result to \fInum\fR;
-then the control escape evaluates \fInum\fR. If \fInum\fR is non-zero,
-the string \*(lqTo: \*(rq is printed followed by the value of the header
-component \*(lqTo:\*(rq.
-
-A minor explanation of (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
-In general, it checks each of the addresses in the header component
+.RE
+.PP
+(A clarification on (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
+This function checks each of the addresses in the header component
\*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
-\fIAlternate-Mailboxes\fR. It returns true if any address matches,
-however, it also returns true if the \*(lq\fIcomp\fR\*(rq header is not
-present in the message. If needed, the (\fInull\fR\^) function can be
-used to explicitly test for this condition.
-
+.RI \*(lq Alternate-Mailboxes \*(rq.
+It returns true if any address matches. However, it also returns true
+if the \*(lq\fIcomp\fR\*(rq header is not present in the message.
+If needed, the (\fInull\fR\^) function can be used to explicitly
+test for this case.)
+.SS Formatting
When a function or component escape is interpreted and the result will
-be immediately printed, an optional field width can be specified to
+be printed immediately, an optional field width can be specified to
print the field in exactly a given number of characters. For example, a
numeric escape like %4(\fIsize\fR\^) will print at most 4 digits of the
message size; overflow will be indicated by a `?' in the first position
characters and truncate at the end. Short fields are padded at the right
with the fill character (normally, a blank). If the field width argument
begins with a leading zero, then the fill character is set to a zero.
-
-As above, the functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
+.PP
+The functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
print their result in exactly the number of characters
specified by their leading field width argument. For example,
%06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
component in fourteen characters with trailing spaces added as needed.
For \fIputstrf\fR, using a negative value for the field width causes
right-justification of the string within the field, with padding on
-the left up to the field width. The functions (\fIputnum\fR\^) and
-(\fIputstr\fR\^) print their result in the minimum number of characters
-required, and ignore any leading field width argument.
-
+the left up to the field width.
+The functions (\fIputnum\fR\^) and
+(\fIputstr\fR\^) are somewhat special: they print their result in the
+minimum number of characters required, and ignore any leading field width
+argument. The (\fIputlit\fR\^) function outputs the exact contents of the
+str register without any changes such as duplicate space removal or control
+character conversion. Similarly, the (\fIzputlit\fR\^) function outputs
+the exact contents of the str register, but requires that those contents
+not occupy any output width. It can therefore be used for outputting
+terminal escape sequences.
+.PP
+There are a limited number of function escapes to output terminal escape
+sequences. These sequences are retrieved from the
+.IR terminfo (5)
+database according to the current terminal setting. The (\fIbold\fR\^),
+(\fIunderline\fR\^), and (\fIstandout\fR\^) escapes set bold mode,
+underline mode, and standout mode respectively.
+(\fIhascolor\fR\^)
+can be used to determine if the current terminal supports color.
+(\fIfgcolor\fR\^) and (\fIbgcolor\fR\^) set the foreground and
+background colors respectively. Both of these escapes take one literal
+argument, the color name, which can be one of: black, red, green, yellow,
+blue, magenta, cyan, white. (\fIresetterm\fR\^) resets all terminal
+attributes to their default setting. These terminal escapes should be
+used in conjunction with (\fIzputlit\fR\^) (preferred) or
+(\fIputlit\fR\^), as the normal (\fIputstr\fR\^) function will strip
+out control characters.
+.PP
The available output width is kept in an internal register; any output
-past this width will be truncated.
-
-Comments may be inserted in most places where a function argument is
-not expected. A comment begins with `%;' and ends with a (non-escaped)
-newline.
-
-With all this in mind,
-here's the default format string for \fIscan\fR.
-It's been divided into several pieces for readability.
+exceeding this width will be truncated. The one exception to this is that
+(\fIzputlit\fR\^) functions will still be executed if a terminal
+reset code is being placed at the end of a line.
+.SS Special Handling
+Some functions have different behavior depending on the command they are
+invoked from.
+.PP
+In
+.B repl
+the (\fIformataddr\fR\^) function stores all email addresses encountered into
+an internal cache and will use this cache to suppress duplicate addresses.
+If you need to create an address list that includes previously-seen
+addresses you may use the (\fIconcataddr\fR\^) function, which is identical
+to (\fIformataddr\fR\^) in all other respects. Note that (\fIconcataddr\fR\^)
+does
+.I not
+add addresses to the duplicate-suppression cache.
+.SS Other Hints and Tips
+Sometimes, the writer of a format function is confused because output is
+duplicated. The general rule to remember is simple: If a function or
+component escape begins with a `%', it will generate text in the output file.
+Otherwise, it will not.
+.PP
+A good example is a simple attempt to generate a To: header based on
+the From: and Reply-To: headers:
+.PP
+.RS 5
+.nf
+%(formataddr %<{reply-to}%|%{from})%(putaddr To: )
+.fi
+.RE
+.PP
+Unfortunately, if the Reply-to: header is
+.I not
+present, the output line
+will be something like:
+.PP
+.RS 5
+.nf
+My From User <from@example.com>To: My From User <from@example.com>
+.fi
+.RE
+.PP
+What went wrong? When performing the test for the
+.B if
+clause (%<), the component is not output because it is considered an
+argument to the
+.B if
+statement (so the rule about not starting with % applies). But the component
+escape in our
+.B else
+statement (everything after the `%|') is
+.I not
+an argument to anything;
+it begins with a %, and thus the value of that component is output.
+This also has the side effect of setting the
+.I str
+register, which is later picked up by the (\fIformataddr\fR\^) function
+and then output by (\fIputaddr\fR\^). The example format string above
+has another bug: there should always be a valid width value in the
+.I num
+register when (\fIputaddr\fR\^) is called, otherwise bad formatting can take
+place.
+.PP
+The solution is to use the (\fIvoid\fR\^) function; this will prevent the
+function or component from outputting any text. With this in place (and
+using (\fIwidth\fR\^) to set the
+.I num
+register for the width) a better implementation would look like:
+.PP
+.RS 3
+.nf
+%(formataddr %<{reply-to}%|%(void{from})%(void(width))%(putaddr To: )
+.fi
+.RE
+.PP
+It should be noted here that the side effects of function and component
+escapes are still in force and, as a result, each component test in the
+.B if-elseif-else-endif
+clause sets the
+.I str
+register.
+.PP
+As an additional note, the (\fIformataddr\fR\^) and (\fIconcataddr\fR\^)
+functions have special behavior when it comes to the
+.I str
+register. The starting point of the register is saved and is used to
+build up entries in the address list.
+.PP
+You will find the
+.IR fmttest (1)
+utility invaluable when debugging problems with format strings.
+.SS Examples
+With all the above in mind, here is a breakdown of the default format string for
+.BR scan .
The first part is:
-
-.ti +.5i
+.PP
+.RS
+.nf
%4(msg)%<(cur)+%| %>%<{replied}\-%?{encrypted}E%| %>
-
-which says that the message number should be printed in four digits,
-if the message is the current message then a `+' else a space should
-be printed, and if a \*(lqReplied:\*(rq field is present then a `\-'
-else if an \*(lqEncrypted:\*(rq field is present then an `E' otherwise
-a space should be printed. Next:
-
-.ti +.5i
+.fi
+.RE
+.PP
+which says that the message number should be printed in four digits.
+If the message is the current message then a `+', else a space, should
+be printed; if a \*(lqReplied:\*(rq field is present then a `\-',
+else if an \*(lqEncrypted:\*(rq field is present then an `E', otherwise
+a space, should be printed. Next:
+.PP
+.RS
+.nf
%02(mon{date})/%02(mday{date})
-
+.fi
+.RE
+.PP
the month and date are printed in two digits (zero filled) separated by
-a slash.
-Next,
-
-.ti +.5i
-%<{date} %|*>
-
-If a \*(lqDate:\*(rq field was present,
-then a space is printed, otherwise a `*'.
+a slash. Next,
+.PP
+.RS 5
+.nf
+%<{date} %|*%>
+.fi
+.RE
+.PP
+If a \*(lqDate:\*(rq field is present it is printed, followed by a space;
+otherwise a `*' is printed.
Next,
-
-.ti +.5i
-%<(mymbox{from})%<{to}To:%14(friendly{to})%>%>
-
-if the message is from me,
-and there is a \*(lqTo:\*(rq header,
-print `To:' followed by a \*(lquser-friendly\*(rq rendering of the
-first address in the \*(lqTo:\*(rq field.
+.PP
+.RS 5
+.nf
+%<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>
+.fi
+.RE
+.PP
+if the message is from me, and there is a \*(lqTo:\*(rq header,
+print \*(lqTo:\*(rq followed by a \*(lquser-friendly\*(rq rendering of the
+first address in the \*(lqTo:\*(rq field; any MIME-encoded
+characters are decoded into the actual characters.
Continuing,
-
-.ti +.5i
-%<(zero)%17(friendly{from})%>
-
+.PP
+.RS 5
+.nf
+%<(zero)%17(decode(friendly{from}))%>
+.fi
+.RE
+.PP
if either of the above two tests failed,
then the \*(lqFrom:\*(rq address is printed
-in a \*(lquser-friendly\*(rq format.
+in a mime-decoded, \*(lquser-friendly\*(rq format.
And finally,
-
-.ti +.5i
-%{subject}%<{body}<<%{body}%>
-
-the subject and initial body (if any) are printed.
-
-For a more complicated example, next consider
-the default \fIreplcomps\fR format file.
-
-.ti +.5i
+.PP
+.RS 5
+.nf
+%(decode{subject})%<{body}<<%{body}>>%>
+.fi
+.RE
+.PP
+the mime-decoded subject and initial body (if any) are printed.
+.PP
+For a more complicated example, consider a possible
+.I replcomps
+format file.
+.PP
+.RS 5
+.nf
%(lit)%(formataddr %<{reply-to}
-
-This clears \fIstr\fR and formats the \*(lqReply-To:\*(rq header
+.fi
+.RE
+.PP
+This clears
+.I str
+and formats the \*(lqReply-To:\*(rq header
if present. If not present, the else-if clause is executed.
-
-.ti +.5i
+.PP
+.RS 5
+.nf
%?{from}%?{sender}%?{return-path}%>)\\
-
-This formats the
+.fi
+.RE
+.PP
+This formats the
\*(lqFrom:\*(rq, \*(lqSender:\*(rq and \*(lqReturn-Path:\*(rq
headers, stopping as soon as one of them is present. Next:
-
-.ti +.5i
+.PP
+.RS 5
+.nf
%<(nonnull)%(void(width))%(putaddr To: )\\n%>\\
-
+.fi
+.RE
+.PP
If the \fIformataddr\fR result is non-null, it is printed as
an address (with line folding if needed) in a field \fIwidth\fR
-wide with a leading label of \*(lqTo: \*(rq.
-
-.ti +.5i
+wide, with a leading label of \*(lqTo:\*(rq.
+.PP
+.RS 5
+.nf
%(lit)%(formataddr{to})%(formataddr{cc})%(formataddr(me))\\
-
-\fIstr\fR is cleared, and the
-\*(lqTo:\*(rq and \*(lqCc:\*(rq headers, along with the user's
-address
-(depending on what was specified with
+.fi
+.RE
+.PP
+.I str
+is cleared, and the \*(lqTo:\*(rq and \*(lqCc:\*(rq headers, along with the user's
+address (depending on what was specified with
the \*(lq\-cc\*(rq switch to \fIrepl\fR\^) are formatted.
-
-.ti +.5i
+.PP
+.RS 5
+.nf
%<(nonnull)%(void(width))%(putaddr cc: )\\n%>\\
-
+.fi
+.RE
+.PP
If the result is non-null, it is printed as above with a
-leading label of \*(lqcc: \*(rq.
-
-.ti +.5i
+leading label of \*(lqcc:\*(rq.
+.PP
+.RS 5
+.nf
%<{fcc}Fcc: %{fcc}\\n%>\\
-
-If a \*(lq\-fcc\ folder\*(rq switch was given to \fIrepl\fR
-(see \fIrepl\fR\0(1) for more details about %{\fIfcc\fR\^}),
+.fi
+.RE
+.PP
+If a
+.B \-fcc
+.I folder
+switch was given to
+.B repl
+(see
+.IR repl (1)
+for more details about %{\fIfcc\fR\^}),
an \*(lqFcc:\*(rq header is output.
-
-.ti +.5i
+.PP
+.RS 5
+.nf
%<{subject}Subject: Re: %{subject}\\n%>\\
-
+.fi
+.RE
+.PP
If a subject component was present,
a suitable reply subject is output.
-
+.PP
+.RS 5
.nf
-.ti +.5i
-%<{date}In-reply-to: Your message of "\\
-.ti +.5i
-%<(nodate{date})%{date}%|%(pretty{date})%>."%<{message-id}
-.ti +.5i
- %{message-id}%>\\n%>\\
-.ti +.5i
+%<{message-id}In-Reply-To: %{message-id}\\n%>\\
+%<{message-id}References: %<{references} %{references}%>\\
+%{message-id}\\n%>
\-\-\-\-\-\-\-\-
.fi
-
-If a date component was present, an \*(lqIn-Reply-To:\*(rq header is
-output with the preface \*(lqYour message of \*(rq. If the date was
-parseable, it is output in a user-friendly format, otherwise it is
-output as-is. The message-id is included if present. As with all
+.RE
+.PP
+If a message-id component was present, an \*(lqIn-Reply-To:\*(rq header is
+output including the message-id, followed by a \*(lqReferences:\*(rq
+header with references, if present, and the message-id.
+As with all
plain-text, the row of dashes are output as-is.
-
+.PP
This last part is a good example for a little more elaboration.
Here's that part again in pseudo-code:
-.sp 1
+.PP
+.RS 5
.nf
-.in +.5i
.ta .5i 1i 1.5i 2i
-if (comp_exists(date)) then
- print (\*(lqIn-reply-to: Your message of \\\*(lq\*(rq)
- if (not_date_string(date.value) then
- print (date.value)
- else
- print (pretty(date.value))
- endif
- print (\*(lq\\\*(rq\*(rq)
- if (comp_exists(message-id)) then
- print (\*(lq\\n\\t\*(rq)
- print (message-id.value)
+if (comp_exists(message-id)) then
+ print (\*(lqIn-reply-to: \*(rq)
+ print (message-id.value)
+ print (\*(lq\\n\*(rq)
+endif
+if (comp_exists(message-id)) then
+ print (\*(lqReferences: \*(rq)
+ if (comp_exists(references)) then
+ print(references.value);
endif
+ print (message-id.value)
print (\*(lq\\n\*(rq)
endif
-.re
-.in -.5i
.fi
-.sp 1
-Although this seems complicated,
-in point of fact,
-this method is flexible enough to extract individual fields and print them in
-any format the user desires.
-.Fi
-None
-.Pr
-None
-.Sa
-scan(1), repl(1), ap(8), dp(8)
-.De
-None
-.Co
+.RE
+.PP
+.\" (Note that this pseudocode begs the question ``why not just
+.\" support this syntax?'' MH has been hacked on for a long time...)
+.\".PP
+One more example: Currently,
+.B nmh
+supports very large message numbers, and it is not uncommon for a folder
+to have far more than 10000 messages.
+.\" (Indeed, the original MH
+.\" tutorial document by Rose and Romine is entitled "How to
+.\" process 200 messages a day and still get some real work
+.\" done." The authors apparently only planned to get
+.\" real work done for about 50 days per folder.)
+Nonetheless (as noted above) the various scan format strings, inherited
+from older MH versions, are generally hard-coded to 4 digits for the message
+number. Thereafter, formatting problems occur.
+The nmh format strings can be modified to behave more sensibly with larger
+message numbers:
+.PP
+.RS
+.nf
+%(void(msg))%<(gt 9999)%(msg)%|%4(msg)%>
+.fi
+.RE
+.PP
+The current message number is placed in \fInum\fP.
+(Note that
+.RI ( msg )
+is a function escape which returns an integer, it is not a component.)
+The
+.RI ( gt )
+conditional
+is used to test whether the message number
+has 5
+or more digits.
+If so, it is printed at full width, otherwise
+at 4 digits.
+.SH "SEE ALSO"
+.IR scan (1),
+.IR repl (1),
+.IR fmttest (1)
+.SH CONTEXT
None
-.En
projects / nmh / blobdiff