Hi Everyone,

I haven't much experience writting Perl code on Unix, as the company where I work as a Unix administrator only uses the Korn shell, Awk and Sed for everything. For my current project, I have to use Perl :-).As I have never seen or used perl in a system admin role on Unix, I haven't developed my own style. I would value the monks advise on the user of system() and programming style.

In my scripts I need to deport and import volume manger disk groups in order to take a point-in-time copy. Each command must be check to ensure that I get clean copy of the disk group. If I were using the Korn Shell, when I need to check the return code, the code would look something like: 

vxdg deport oracle
if [ $? ]
then
  echo "Could not deport oracle"
  exit 1
fi

[download]

From digging through the Camel book and perldocs, I read that when executing a command using the system function, $? needs to be shifted by eight bytes to get the proper return code. From searching the net, I have seen this implemented in a variety different way, such as: 

system ("vxdg deport oracle");
if ($?){
  $rc = $_ >> 8;
  print "Could not deport oracle";
  exit 1;
}

[download]

What I am unsure about is what is then best/efficient way of implementing this. Is it better to carry out the $rc = $_ >> 8; operation after every system call and then check the return code, or would it be better to encase system within the if statement?, and only do the $rc = $_ >> 8; where I absolutely need to use the proper return code.

Thanks,
Darren

In reply to System and a question of style by D.Millin

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