Re: Question about expansion: redirection(<) vs command(cat)

Considering that the word here is explicitly a filename to be read, it is
quite odd that it doesn't undergo filename generation. If it were not
documented, I would even go so far as to suggest that it's a bug.

Worth noting that both bash and ksh do filename expansion in this construct
(triggering an "ambiguous" warning if the pattern expands to more than one
filename). Also, zsh's lack of filename expansion here is not affected by
GLOB_SUBST.

On Tue, Jan 13, 2026 at 4:19 PM Bart Schaefer <[email protected]>
wrote:

> On Tue, Jan 13, 2026 at 11:09 AM Jim <[email protected]> wrote:
> >
> > The following produced the expected output.
> > Array=(${(f)"$(< /usr/share/zsh/5.9/scripts/newuser)"}) ; print $?
> >
> > But when expansion is required the following fails.
> > Array=(${(f)"$(< /usr/share/zsh/<->.*/scripts/newuser)"}) ; print $?
>
> The issue here is that the token "$(<" is a special case of "$(" and
> not a special case of "<" redirection.  Docs under "Command
> Substitution":
>
>   The substitution '$(cat FOO)' may be replaced by the faster '$(<FOO)'.
>   In this case FOO undergoes single word shell expansions (_parameter
>   expansion_, _command substitution_ and _arithmetic expansion_), but not
>   filename generation.  No subshell is created.
>
> Note "but not filename generation".
>
>

-- 
Mark J. Reed <[email protected]>