R help - Jan 2008 - Capturing info from system calls in Windows

Colleagues,

I am preparing scripts that will be used by others on both Windows and  
Linux/OSX platforms.  The scripts call an existing Fortran  
application.  The user may have any of a a variety of Fortran  
compilers - my goal is to determine whether or not the test command  
returns "no input files" or "command not found" (i.e., so
that I can
confirm which Fortran they are using).

In OS X and Linux, I can do the following:
> > TEST <- system("g77 2>&1", intern=TRUE)
> > TEST
> [1] "g77: no input files"
>
> > TEST <- system("f77 2>&1", intern=TRUE)
> > TEST
> [1] "sh: f77: command not found"
I can then use grep to determine which of the two strings was returned.

In Windows:
> > TEST <- system("g95 2>&1")
> g95: 2>&1: Invalid argument
> > TEST
> [1] 0
> attr(, "exec.status"):
> [1] 0
> attr(, "exit.status"):
> [1] 0
> >
> > TEST <- system("g95")
> g95: no input files
> > TEST
> [1] 0
> attr(, "exec.status"):
> [1] 0
> attr(, "exit.status"):
> [1] 0
As you can see, Windows replies "no input files"; however, that info  
is not captured in TEST.  I presume that this is because standard  
error is dealt with different in Windows compared to Unix-line  
platforms.  Any thoughts on how to capture standard error in Windows?

Dennis


Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-415-564-2220
www.PLessThan.com


	[[alternative HTML version deleted]]

On 26/01/2008 9:17 AM, Dennis Fisher wrote:
> Colleagues,
> 
> I am preparing scripts that will be used by others on both Windows and  
> Linux/OSX platforms.  The scripts call an existing Fortran  
> application.  The user may have any of a a variety of Fortran  
> compilers - my goal is to determine whether or not the test command  
> returns "no input files" or "command not found" (i.e.,
so that I can
> confirm which Fortran they are using).
> 
> In OS X and Linux, I can do the following:
>>> TEST <- system("g77 2>&1", intern=TRUE)
>>> TEST
>> [1] "g77: no input files"
>>
>>> TEST <- system("f77 2>&1", intern=TRUE)
>>> TEST
>> [1] "sh: f77: command not found"
> I can then use grep to determine which of the two strings was returned.
> 
> In Windows:
>>> TEST <- system("g95 2>&1")
>> g95: 2>&1: Invalid argument
>>> TEST
>> [1] 0
>> attr(, "exec.status"):
>> [1] 0
>> attr(, "exit.status"):
>> [1] 0
>>> TEST <- system("g95")
>> g95: no input files
>>> TEST
>> [1] 0
>> attr(, "exec.status"):
>> [1] 0
>> attr(, "exit.status"):
>> [1] 0
> 
> As you can see, Windows replies "no input files"; however, that
info
> is not captured in TEST.  I presume that this is because standard  
> error is dealt with different in Windows compared to Unix-line  
> platforms.  Any thoughts on how to capture standard error in Windows?
See ?system.  You want intern=TRUE there, too.

 > system("gcc")
gcc.exe: no input files
 > system("gcc", intern=TRUE)
[1] "gcc.exe: no input files"


Duncan Murdoch
> 
> Dennis
> 
> 
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-415-564-2220
> www.PLessThan.com
> 
> 
> 	[[alternative HTML version deleted]]
> 
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