Re: [PATCH] base-files-4.0.6: Change prompt if running with admin rights

[Christian Franke <Christian.Franke@t-online.de>]

Daniel Colascione wrote:
> On 4/24/11 9:39 AM, Christian Franke wrote:
>    
>> On 2011-04-01, Christian Franke wrote:
>>      
>>> The attached patch for /etc/profile and /etc/bash.bashrc sets a root
>>> prompt ('#' instead of '$' or '%') if the shell runs with admin rights
>>> (local or domain admin group).
>>>
>>>        
>> Any comment so far? Wrong list ?
>>      
>
> I like the idea, but your patch adds two subprocess invocations to the
> shell startup path. Each one takes ~200ms, and we can't afford to add
> any more.
>
>    

Agree.


> Instead of examining the group list, you can use something like
>
> local isadmin=0
> [[ -w / ]]&&  isadmin=1
>
>    

False positive if same user installed Cygwin by running setup.exe with 
admin rights.

[[...]] does not work with posh and dash. But all shells apparently have 
a builtin '[' command.


> or
>
> local isadmin=0
> [[ -w /cygdrive/c ]]&&  isadmin=1
>
>    

False positive if /cygdrive is mounted with 'noacl' option.


> Of course, that test assumes that only "administrators" can write to the
> drive root, and that's an imperfect proxy for administrative rights. You
> get the idea though: try to perform the test in pure bash code.
>
>    

Using a read access test on a registry key with SYSTEM only access might 
work in most cases:

[ -r /proc/registry/HKEY_LOCAL_MACHINE/SECURITY ] && isadmin=1

Test succeeds if SeBackupPrivilege is enabled which is the case for 
Cygwin processes if user is in admin group or another group with this 
privilege.

A test script for all shells is attached. Run with admin rights. 
Requires cygdrop from cygutils package.

Script produces a false negative only from dash. Not really an issue, as 
dash is normally not used interactively.

Christian


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