R help - Jun 2009 - system function question

Dear R People:

Does the system function return a code, (maybe zero if ok, non-zero
otherwise), please?



Thanks,
Erin


-- 
Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

Erin Hodgess wrote:
> Dear R People:
> 
> Does the system function return a code, (maybe zero if ok, non-zero
> otherwise), please?
Dear Erin,

it depends on its arguments and the OS. See the "value" section of
?system.

Best,
Uwe


> 
> 
> 
> Thanks,
> Erin
> 
>

On Tue, 30 Jun 2009, Erin Hodgess wrote:
> Dear R People:
>
> Does the system function return a code, (maybe zero if ok, non-zero
> otherwise), please?
>
Let's see
> a<-system("ls")
> str(a)
  int 0
> a<-system("ls foo")
ls: foo: No such file or directory
> str(a)
  int 256

Sure looks like it.  And the help page seems to agree, too:

If intern = FALSE, the return value is an error code (0 for success), given the
invisible attribute (so needs to be printed explicitly). If the command could
not be run for any reason, the value is 256*127 = 52512. Otherwise if wait =
TRUE the value is 256 times the error code returned by the command, and if wait
= FALSE it is 0 (the conventional success value).

      -thomas

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle