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Re: backslash-period escape does not work
From: |
Werner LEMBERG |
Subject: |
Re: backslash-period escape does not work |
Date: |
Tue, 22 Mar 2011 14:21:28 +0100 (CET) |
> The backslash-period escape sequence in groff doesn't work as
> described in documentation.
>
> Manual page:
> \. An uninterpreted dot (period), even at start of line.
>
> Minimal reproducer:
> $ groff -wmac -Tascii <<< '\.foo'
> <standard input>:1: warning: macro `foo' not defined
As Tadziu has already stated, this is a documentation bug. The
description in the groff info manual is better but perhaps not
optimal. Below you can find the description of both `\\' (shortened)
and `\.'.
-- Escape: \\
[...]
`\\' is a `delayed' backslash; more precisely, it is the default
escape character followed by a backslash, which no longer has
special meaning due to the leading escape character. It is _not_
an escape sequence in the usual sense! In any unknown escape
sequence `\X' the escape character is ignored and X is printed.
But if X is equal to the current escape character, no warning is
emitted.
As a consequence, only at top-level or in a diversion a backslash
glyph is printed; in copy-in mode, it expands to a single
backslash which then combines with the following character to an
escape sequence.
[...]
-- Escape: \.
Similar to `\\', the sequence `\.' isn't a real escape sequence.
As before, a warning message is suppressed if the escape character
is followed by a dot, and the dot itself is printed.
Any suggestions and patches to improve both the short doc string in
the man page and the longer info page details are highly welcomed.
Werner