On Thu, 2006-09-21 at 17:21 -0700, Greg Frinchaboy wrote:
> This may be an old issue but I could not find info in the archives.
>
> u_int num_cpus = system("cat /proc/cpuinfo | grep -c processor >
> /dev/null");
>
> Has yielded the number of cpus on the system since I used it in RH7.3
> and fc3.
> Now in fc5, all uses of system("cmd"); return -1
>
> The command executes OK, just the return value is always -1.
>
> u_int num_cpus = system("cat /proc/cpuinfo");
> dumps the cpuinfo file to the system console
>
> u_int num_cpus = system("cat /proc/cpuinfo | grep -c processor");
> dumps a 2 to the system console, etc.
>
> Any help would be appreciated...
> Greg
your line of code suggests you expect system() to return you an integer
parsed from the console output of your command. This isn't what system
does:
man system
"The value returned is -1 on error (e.g. fork() failed), and the return
status of the command otherwise."
"grep -c" puts the count of the matches found on stdout, and returns a
status of zero if something is found and 1 otherwise (and 2 on error).
So I'd expect your "num_cpus" to be zero, typically, and 1 if no
'processor' string was found in /proc/cpuinfo. Indeed, that's exactly
what happened when I tried it just now.
By the way, at the command line you can use "echo $?" to show the exit
status of the last executed command.
Hope that helps.
Matt Davey I went to a Grateful Dead Concert and they played
mcdavey@xxxxxxxxxxxxxx for SEVEN hours. Great song.
