Mysterious (debug?) output in loop

Mysterious (debug?) output in loop

[Dominik Vogt]

Running this script

--- snip ---
#!/usr/bin/zsh
emulate zsh
repeat 3; do
	local FOO
	FOO="0"
done
--- snip ---

Produces this output:

  $ ./foo
  FOO=0
  FOO=0

  $ zsh --version
  zsh 5.8 (x86_64-debian-linux-gnu)

Why does it print 'FOO=0' to stdout (not stderr) in all passes of
the loop except the first one?  Is that some forgotten debug
output?  Is there a way to disable that (without writing the
script in a different way)?

Of course I'm aware that (a) using local variables in global scope
is useless and (b) variables are local to functions, not local to
loops.  Before stripping down the test case, it was some code in a
function.  Moving 'local FOO' out of the loop, or replacing it
with 'local FOO="0"' suppresses the output.

Ciao

Dominik ^_^  ^_^

--

Dominik Vogt

Re: Mysterious (debug?) output in loop

[Roman Perepelitsa]

On Sun, Jan 29, 2023 at 9:19 PM Dominik Vogt <dominik.vogt@gmx.de> wrote:
>
> Running this script
>
> --- snip ---
> #!/usr/bin/zsh
> emulate zsh
> repeat 3; do
>         local FOO
>         FOO="0"
> done
> --- snip ---
>
> Produces this output:
>
>   $ ./foo
>   FOO=0
>   FOO=0
>
>   $ zsh --version
>   zsh 5.8 (x86_64-debian-linux-gnu)
>
> Why does it print 'FOO=0' to stdout (not stderr) in all passes of
> the loop except the first one?

That's what `local` does by default. You can `setopt typeset_silent`
to disable this (I always do in all my scripts).

Roman.

Re: Mysterious (debug?) output in loop

[Bart Schaefer]

On Sun, Jan 29, 2023 at 12:18 PM Dominik Vogt <dominik.vogt@gmx.de> wrote:
>
> Why does it print 'FOO=0' to stdout (not stderr) in all passes of
> the loop except the first one?

Doc reference:

     If the shell option TYPESET_SILENT is not set, for each remaining
     NAME that refers to a parameter that is already set, the name and
     value of the parameter are printed in the form of an assignment.
     Nothing is printed for newly-created parameters, or when any
     attribute flags listed below are given along with the NAME.

Re: Mysterious (debug?) output in loop

[Sebastian Gniazdowski]

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You can find some other useful options here:
https://zdharma-continuum.github.io/Zsh-100-Commits-Club/Zsh-Plugin-Standard.html#std-options

niedz., 29 sty 2023, 21:19 użytkownik Dominik Vogt <dominik.vogt@gmx.de>
napisał:

> Running this script
>
> --- snip ---
> #!/usr/bin/zsh
> emulate zsh
> repeat 3; do
>         local FOO
>         FOO="0"
> done
> --- snip ---
>
> Produces this output:
>
>   $ ./foo
>   FOO=0
>   FOO=0
>
>   $ zsh --version
>   zsh 5.8 (x86_64-debian-linux-gnu)
>
> Why does it print 'FOO=0' to stdout (not stderr) in all passes of
> the loop except the first one?  Is that some forgotten debug
> output?  Is there a way to disable that (without writing the
> script in a different way)?
>
> Of course I'm aware that (a) using local variables in global scope
> is useless and (b) variables are local to functions, not local to
> loops.  Before stripping down the test case, it was some code in a
> function.  Moving 'local FOO' out of the loop, or replacing it
> with 'local FOO="0"' suppresses the output.
>
> Ciao
>
> Dominik ^_^  ^_^
>
> --
>
> Dominik Vogt
>
>

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