[Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Zaxebo Yaxebo]

[-- Attachment #1: Type: text/plain, Size: 1046 bytes --]

https://en.wikipedia.org/wiki/Friendly_interactive_shell#Universal_variables

Universal variables

*"Fish Shell" has a feature known as universal variables, which allow a
user to permanently assign a value to a variable across all the running
fish shells of that user. The variable value is remembered across logouts
and reboots, and updates in value are immediately propagated to all running
shells.*
 # This will make emacs the default text editor. The '-U' tells fish to
 # make this a universal variable.
 > set -U EDITOR emacs

 # This command will make the current working directory part of the fish
 # prompt turn blue on all running fish instances.
 > set -U fish_color_cwd blue

=======================
I request that this feature may be implemented in zsh
If I have two different zsh shell instances running from same user login
and i give this following command in one zsh instance
  export -U varname=varvalue
  OR, exportglobal varname=varvalue

then i can access it in my another zsh instance running from the same
userlogin.


Zax

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Christian Neukirchen]

Zaxebo Yaxebo <zaxebo1@gmail.com> writes:

> *"Fish Shell" has a feature known as universal variables, which allow a
> user to permanently assign a value to a variable across all the running
> fish shells of that user. The variable value is remembered across logouts
> and reboots, and updates in value are immediately propagated to all running
> shells.*

Unix already has this feature built-in, it's called "files".

-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Bart Schaefer]

On Jul 12,  6:42pm, Zaxebo Yaxebo wrote:
}
} *"Fish Shell" has a feature known as universal variables, which allow a
} user to permanently assign a value to a variable across all the running
} fish shells of that user. The variable value is remembered across logouts
} and reboots, and updates in value are immediately propagated to all running
} shells.*

This was previously discussed in the thread starting here:

http://www.zsh.org/cgi-bin/mla/redirect?USERNUMBER=19431

The thread branches a bit but nobody suggested anything better than this:

http://unix.stackexchange.com/questions/137077/serialize-shell-variable-in-bash-or-zsh

We're almost certainly not going to implement the fish model of having a
background server process that all other shells can contact to receive
environment variable updates.

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[ZyX]

13.07.2015, 01:43, "Bart Schaefer" <schaefer@brasslantern.com>:
>   On Jul 12, 6:42pm, Zaxebo Yaxebo wrote:
>   }
>   } *"Fish Shell" has a feature known as universal variables, which allow a
>   } user to permanently assign a value to a variable across all the running
>   } fish shells of that user. The variable value is remembered across logouts
>   } and reboots, and updates in value are immediately propagated to all running
>   } shells.*
>
>   This was previously discussed in the thread starting here:
>
>   http://www.zsh.org/cgi-bin/mla/redirect?USERNUMBER=19431
>
>   The thread branches a bit but nobody suggested anything better than this:
>
>   http://unix.stackexchange.com/questions/137077/serialize-shell-variable-in-bash-or-zsh
>
>   We're almost certainly not going to implement the fish model of having a
>   background server process that all other shells can contact to receive
>   environment variable updates.



AFAIK there is no longer such a thing. I am not really following fish development, but recently I received github email with comment to one of my issues (https://github.com/fish-shell/fish-shell/issues/1257#issuecomment-120921485) and it contains, literally:

> @zanchey is this still slated for 3.0 or might we see 2.3, now that 2.2 is out and fishd is out of the picture (I'm not sure how the fishd.${HOST} file fits in now with fishd gone).

Highlight: “now with fishd gone”.

I failed to find GH issue that describes fishd death, but commit log shows that the death starts with https://github.com/fish-shell/fish-shell/commit/6a94b51cbadb8609580fac5c693c02ca4ab39734 (which is in 2.2 release).

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Bart Schaefer]

On Jul 13,  6:17pm, ZyX wrote:
}
} Highlight: "now with fishd gone".
} 
} I failed to find GH issue that describes fishd death, but commit log shows that the death starts with https://github.com/fish-shell/fish-shell/commit/6a94b51cbadb8609580fac5c693c02ca4ab39734 (which is in 2.2 release).

Ah, so they're switching from a daemon to a shared file, using the same
file that the daemon previously maintained for data persistence.

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Mikael Magnusson]

On Mon, Jul 13, 2015 at 12:42 AM, Bart Schaefer
<schaefer@brasslantern.com> wrote:
> On Jul 12,  6:42pm, Zaxebo Yaxebo wrote:
> }
> } *"Fish Shell" has a feature known as universal variables, which allow a
> } user to permanently assign a value to a variable across all the running
> } fish shells of that user. The variable value is remembered across logouts
> } and reboots, and updates in value are immediately propagated to all running
> } shells.*
>
> This was previously discussed in the thread starting here:
>
> http://www.zsh.org/cgi-bin/mla/redirect?USERNUMBER=19431
>
> The thread branches a bit but nobody suggested anything better than this:
>
> http://unix.stackexchange.com/questions/137077/serialize-shell-variable-in-bash-or-zsh
>
> We're almost certainly not going to implement the fish model of having a
> background server process that all other shells can contact to receive
> environment variable updates.

One half of it is fairly easy, you can just install a zle -F handler
(possibly coupled with the zsh/socket module) that updates parameters
that another process sends it. The other half, hooking into an
assignment of an arbitrary parameter to send it out again, I can't
think of any way of doing. Maybe you could have a set of functions
that maintains an array of parameter names, and check in zle-line-init
or something if any of them changed. I don't think we would want to
add "parameter assignment hooks"? eg, analogous to typeset -T you
would do typeset -P myfunction someparameter, and then myfunction is
called with someparameter as an argument (and the new value? and you
could assign to someparameter inside that function without causing a
recursive thing maybe). Anyway, I don't think we want that ;).

-- 
Mikael Magnusson

Re: [Feature Request]: Globally updated Variables for all zsh instances for same user - just like fish shell

[Bart Schaefer]

On Jul 13,  8:04pm, Mikael Magnusson wrote:
}
} > We're almost certainly not going to implement the fish model of having a
} > background server process that all other shells can contact to receive
} > environment variable updates.
} 
} One half of it is fairly easy, you can just install a zle -F handler
} (possibly coupled with the zsh/socket module) that updates parameters
} that another process sends it.

The example in the doc for "zle -F" provides a template for this, but I
think a file-based exchange would be preferable.

} The other half, hooking into an
} assignment of an arbitrary parameter to send it out again, I can't
} think of any way of doing.

There's no good way to make "export -U" work, but a module implemented
in the manner of zsh/db/gdbm could define the "exportglobal" command
to create specially-tied variables.  Could even use a GDBM file as the
persistence mechanism, it'd be almost exactly the same as what db_gdbm.c
already does if you limit the universal globals to scalars (otherwise
you have to deal with serializing arrays/hashes).