sysrc -- a sysctl(8)-like utility for managing /etc/rc.conf et. al.

[Devin Teske]

On Oct 10, 2010, at 4:51 PM, Garance A Drosihn wrote:

> On 10/10/10 7:09 PM, Devin Teske wrote: 
>> However, enclosing the argument (as the 'x$foo' portion is really just the first argument to the '[' built-in) in quotes:
>> 
>> [ "$foo" = x ]
>> 
>> makes it so that the expansion is taken as:
>> 
>> [ "-n" = x ]
>> 
>> rather than:
>> 
>> [ -n = x ]
>> 
>> The former not causing an error, while the latter does.
>>   
> The latter does not cause an error.  Try it:
> 
> # [ "-n" = x ] ; echo $?
> 1
> 
> # [ -e = "no" ] ; echo $?
> 1
> 
> # [ -e = -n ] ; echo $?
> 1

Logical error, not functional error.


>> Quite functionally, at a C-level, if you have your array, ...
>> 
>> argv[0] = "[\0";
>> argv[1] = "\"-n\"\0"; /* quoted syntax */
>> argv[2] = "=\0";
>> argv[3] = "x\0";
>> 
>> and
>> 
>> argv[0] = "[\0";
>> argv[1] = "-n\0"; /* non-quoted syntax */
>> argv[2] = "=\0";
>> argv[3] = "x\0";
>> 
>>   
> You won't see the double-quotes in the C program.

Correct, an external C programming will get the arguments just like a shell script.


>   The shell processes single and double quotes, and passes the result to the C program which is running.  It might be different for built-in functions,

Indeed it is.


> but /bin/test would never see the double-quotes if they were used.  And since the built-in function has to work the same as standalone function

There is no distinction between "built-in function" and "standalone function". I think you mean "built-in" versus "external binary".

The way that parameters are passed off to the internal parser is different than the way arguments are passed to external executables.


> , I doubt the built-in would be any different.
> 
> # list_args "-n"  
> 
> list_args at 19:36:15 Oct 10: $# = 1
>      ARG[000] l=002: '-n'
> # list_args -n
> 
> list_args at 19:36:22 Oct 10: $# = 1
>      ARG[000] l=002: '-n'
> 
> (note that the single-quotes you see there are printed by the list_args script itself for display purposes).
> 
> disclaimer: I think this is the first post that I've made with the new "open-source edition" of Eudora, and I have no idea if this will be formatted the way I'm expecting it be!
> 
> -- 
> Garance Alistair Drosehn     =              drosih at rpi.edu
> Senior Systems Programmer             or   gad at FreeBSD.org
> Rensselaer Polytechnic Institute;           Troy, NY;  USA
> 

--
Cheers,
Devin Teske

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