I'll lump a few issues together here... 1. Backslash escape adjacent to "$@" expansion separates words.
$ set -- abc def ghi; printf '<%s> ' "123 $@ 456"; echo
<123 abc> <def> <ghi 456>
$ set -- abc def ghi; printf '<%s> ' "123 $@\ 456"; echo
<123 abc> <def> <ghi\> <456>
Other shells don't do this (though it might even be useful if the backslash
were removed from the result). Depends on the previous fix for
4.2-p36
2. IFS side-effects don't take effect during expansion.
It isn't clear to me which of these are correct. Bash's interpretation is
unique.
for sh in bb {{d,b}a,po,{m,}k,z}sh; do
printf '%-5s ' "${sh}:"
"$sh" /dev/fd/0
done <<\EOF
${ZSH_VERSION+:} false && emulate sh
set -f -- a b c
unset -v IFS
printf '<%s> ' ${*}${IFS=}${*}${IFS:=-}"${*}"
echo
EOF
bb : <a b cabc> <a-b-c>
dash: <a b cabc> <a-b-c>
bash: <a> <b> <ca> <b> <c-a b c>
posh: <a> <b> <ca b c> <a-b-c>
mksh: <a> <b> <ca b c> <a-b-c>
ksh : <a> <b> <ca> <b> <c> <a b c>
zsh : <a> <b> <ca> <b> <c> <a-b-c>
3. Another IFS oddity via "command"
IFS can be given "two values at once" through the environment of a
redirection.
$ ( set -- 1 2 3; IFS=foo; IFS=- command cat <<<"${IFS} ${*}" )
foo 1-2-3
$ ( set -- 1 2 3; IFS=foo; IFS=- cat <<<"${IFS} ${*}" )
foo 1f2f3
4. Command substitution in redirection evaluated twice on error.
Reproduce by:
$ { <$(echo $RANDOM >&3); } 3>&2 2>/dev/null
25449
8520
There is a 1-liner patch to redir.c for this which might help demonstrate
(thanks to Eduardo A. Bustamante López <dual...@gmail.com>). Skipping this
branch when expandable_redirection_filename is false bypasses a huge chunk
that I haven't looked at closely.
diff --git a/redir.c b/redir.c
index 921be8c..f248fd7 100644
--- a/redir.c
+++ b/redir.c
@@ -153,7 +153,7 @@ redirection_error (temp, error)
}
}
#endif
- else if (expandable_redirection_filename (temp))
+ else if (0)
{
expandable_filename:
if (posixly_correct && interactive_shell == 0)
--
Dan Douglas
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