[nmh] / man / mh-format.man

.TH MH-FORMAT %manext5% 2015-01-10 "%nmhversion%"
.
.\" %nmhwarning%
.
.SH NAME
mh-format \- formatting language for nmh message system
.SH DESCRIPTION
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
.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.  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
.RI %( function " " argument )
.fi
.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
.RI "%< " condition " " "format-text"
.RI "%? " condition " " "format-text"
    ...
.RI "%| " "format-text"
%>
.fi
.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
.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    Nothing %(\fIfunc\fR)
        or a subexpression      %(\fIfunc\fR\^(\fIfunc2\fR\^))
        or control escape       %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
.fi
.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.
.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
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'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
.I "Function    Argument        Return  Description"
msg             integer message number
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 column width of terminal
charleft                integer bytes left in output buffer
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
match   literal boolean \fIstr\fR contains \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.
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 or context
                        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
null    expr    boolean \fIstr\fR is empty
nonnull expr    boolean \fIstr\fR is non-empty
void    expr            Set \fIstr\fR or \fInum\fR
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 (MIME-encoded)
                        component
unquote expr    string  remove RFC 2822 quotes from \fIstr\fR
trim    expr            trim trailing whitespace from \fIstr\fR
trimr   expr    string  Like %(trim), also returns string
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.
ordinal expr    string  Output ordinal suffix based on value
                        of \fInum\fR (st, nd, rd, th)
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
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
.RE
.PP
The following functions require a date component as an argument:
.PP
.RS 5
.nf
.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)
wday    date    integer day of the week (Sun=0)
day     date    string  day of the week (abbrev.)
weekday date    string  day of the week
sday    date    integer day of the week known?
                        (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 minutes
tzone   date    string  timezone string
szone   date    integer timezone explicit?
                        (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? (0 or 1)
clock   date    integer seconds since the Unix epoch
rclock  date    integer seconds prior to current time
tws     date    string  official RFC 822 rendering
pretty  date    string  user-friendly rendering
nodate  date    integer returns 1 if date is invalid
.fi
.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.
.PP
.RS 5
.nf
.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 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 (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 (0 or 1)*
gname   addr    string  name of group*
.fi
.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
.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 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
(like `?234').  A string escape like %4(\fIme\fR\^) will print the first 4
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.
.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
size in a field six characters wide filled with leading zeros;
%14(\fIputstrf\^\fR{\fIfrom\^\fR}) will print the \*(lqFrom:\*(rq header
component in fourteen characters with trailing spaces added as needed.
Using a negative value for the field width causes
right-justification within the field, with padding on
the left up to the field width.
Padding is with spaces except for a left-padded
.I putnumf
when the width starts with zero.
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
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:
.PP
.RS
.nf
%4(msg)%<(cur)+%| %>%<{replied}\-%?{encrypted}E%| %>
.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,
.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,
.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,
.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 mime-decoded, \*(lquser-friendly\*(rq format.
And finally,
.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}
.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.
.PP
.RS 5
.nf
%?{from}%?{sender}%?{return-path}%>)\\
.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:
.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.
.PP
.RS 5
.nf
%(lit)%(formataddr{to})%(formataddr{cc})%(formataddr(me))\\
.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.
.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.
.PP
.RS 5
.nf
%<{fcc}Fcc: %{fcc}\\n%>\\
.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.
.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
%<{message-id}In-Reply-To: %{message-id}\\n%>\\
%<{message-id}References: %<{references} %{references}%>\\
%{message-id}\\n%>
\-\-\-\-\-\-\-\-
.fi
.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:
.PP
.RS 5
.nf
.ta .5i 1i 1.5i 2i
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
.fi
.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