2018-09-30 05:18:03 +0700, Robert Elz:
> Date: Fri, 28 Sep 2018 14:44:55 +0200
> From: Harald van Dijk <a...@gigawatt.nl>
> Message-ID: <d1c042d8-4431-7232-aaf2-9802de0af...@gigawatt.nl>
>
> | 1. Are the rules for determining the end of a dollar-quoted string
> | intended to be fully specified, especially when taking into account
> | strings that are never expanded?
>
> $'' gives a single quoted string, it is never "expanded" in the sense usually
> used in the shell. That is unlike $ expressions in "" strings, which are.
>
> The \ sequences in $'' are more like the \ sequences in "" - they are
> processed
> as the string is read (while tokenisation is being performed).
As already discussed, in zsh (where $'\uxxxx' comes from in the
first place), while the $'...' are of course tokenised correctly
the \x, \uxxxx are expanded at *runtime*. It *is* an expansion
operator as you'd expect.
Just like in $(...), or course the content has to be parsed, but
the command inside is only run at runtime.
Same applies for $"..." and ${parameter:=cmd}. The fact that it
starts with $ suggests it *should* be an expansion.
That
printf %s $'\u00E9'
doesn't behave like
printf '\u00E9'
in some shells is surprising. (yes "printf '\uxxxx'" is not yet
specified by POSIX but not that it predates $'\uxxxx', zsh added
both $'\uxxxx' and printf '\uxxxx' at the same time, inspired by
the GNU printf utility (not the printf builtin of the GNU shell
which added support for \uxxxx much later).
Test case:
eacute() {
printf %s $'\ue9'
}
LC_ALL=en_GB.UTF-8 eacute | od -An -vtx1
LC_ALL=en_GB.iso88591 eacute | od -An -vtx1
LC_ALL=C eacute | od -An -vtx1
Compare with:
eacute() {
printf '\u00e9'
}
--
Stephane
