Re: Redis installation error(s) on Debian SID

[Karl Vogel <vogelke@pobox.com>]

On Sat, Oct 12, 2024 at 21:43:39 -0400, I mistakenly wrote:
> See the ":" followed by two spaces?  Unlike systemctl, well-behaved
> programs set "errno" when they puke, and that setting is turned into
> a more-or-less useful error message like "Permission denied".
> "$!" would have held that message.

>> On Sat 12 Oct 2024 at 22:23:31 (-0400), Greg Wooledge replied:
> I don't think this is correct.  A *function* can set errno (a global
> variable in C), in addition to returning a value.  A process can't,
> unless there has been some major change to the Unix process model that
> I've missed.

  You're right, keyboard in motion before brain in gear.  Since I don't
  have systemctl installed, the system() *function* failed when it tried to
  exec a non-existent program and correctly set "$!" to "No such file
  or directory".

  If I call 'system("/bin/mkdir", "/etc/something")' as myself, the
  /bin/mkdir *process* handles errno and prints "Permission denied".
  All system() sees is a non-0 exit code.

  Removing the --quiet flag and using something like safesys() would:

  * let systemctl write something (hopefully an error message),
  * show exactly what arguments are being passed to it, and
  * show its exit value.

-- 
Karl Vogel                      I don't speak for anyone but myself

In [the movie] "Seven", I put it in my contract:
The wife's head stays in the box.
                            --Brad Pitt on early contract negotiations