Re: Local variables list

[Dieter Britz]

On Thu, 02 Oct 2014 14:25:54 +0200, Pascal J. Bourguignon wrote:

> Dieter Britz <dieterhansbritz@gmail.com> writes:
> 
>> For some files, when I start emacs, I get a warning something like "The
>> local variables list for <file> contains values that may not be
>> safe..." (I was not able to copy/paste so am citing from memory). I
>> then answer "yes" and I get in, but what does this mean? What can I do
>> about it?
> 
> The file local variables are defined either on one of the first two
> lines, between "-*-" and "-*-", or in the last 512 bytes, between
> "\nLocal Variable:\n" and "\nEnd:\n".
> 
> Some local variables are "safe" and/or have "safe" values. For example:
> 
>      ;; -*- mode:lisp; coding:utf-8; -*-
> 
> on the first line define two variables, mode and coding to be set to
> lisp and utf-8 which are all safe.
> 
> Some other local variables or values are not safe.  For example:
> 
>     Local Variable:
>     post-command-hook: ((lambda () (do-some-virus-propagation)))
>     End:
> 
> wouldn't be safe, and neither would:
> 
>     Local Variable:
>     post-command-hook: ((lambda () (shell "rm -rf /")))
>     End:
> 
> It is to protect you from such files, that emacs warns you when it
> detect something strange in file local variables.  You should not answer
> yes blindly, you should check those variables, and convince yourself
> that they are safe, before answering yes.
> 
> The "*Local Variables*"  buffer gives you the list of local variables,
> indicating those that are unsafe:
> 
> 
>     -----(*Local
>     Variables*)------------------------------------------------
>     The local variables list in test-file contains varibles that are
>     risk (**).
> 
>     Do you want to apply it?  You can type y  -- to apply the local
>     variable list.
>     n  -- to ignore the local variables list.
> 
>         mode : text
>      ** post-command-hook : ((lambda nil (message "hi")))
>     
------------------------------------------------------------------------
> 
> Here you can see that post-command-hook looks safe (but it will erase
> the current post-command-hook, so you might still want to answer n (and
> then remove it from the file).

Thanks - I don't fully understand but will watch out for this.
These must get into the file without my doing. I find in one of
these, at the end, the lines

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: t
%%% End: 

How did they get there? What are local variables? I suppose
they are connected with the settings my emacs has (?) - these
must be default because I have never set anything.

-- 
Dieter Britz