Re: Bug with assignments in some commands

[Bart Schaefer <schaefer@brasslantern.com>]

To expand on what PWS wrote:

echo "$((x++)), x is $x" | cat
echo "${x::=2}, x is $x" | cat

Those are both obvious subshells, forked to the left.  POSIX actually
says that ALL commands in a pipeline are to be subshells, but allows
exceptions.

cat <<<"$((x++))"
cat <<END
$((x++)), x is $x
END

Those should also be obvious, "cat" is an external command so the
entire thing (including the here-document input) is forked off.

<<<"$((x++)), x is $x"
<<END
$((x++)), x is $x
END

Those are less obvious, but they are equivalent to

$NULLCMD <<<"$((x++)), x is $x"
$NULLCMD <<END
$((x++)), x is $x
END

which are again forked as separate processes.