$
$
$ cat insania.pl
#!/usr/bin/perl -w
$model  = $ARGV[0];
$kernel = $ARGV[1];
print "Before if...\n";
print "model  = $model\n";
print "kernel = $kernel\n";
# if the model is set to "N\A" and the kernel variable
# has xen somewhere in it i would like to change the
# variable to "virtual machine".
# Otherwise just leave it alone.
if ($model eq "N\\A" and $kernel =~ m/xen/) {
    $model = "Virtual Machine";
}
print "\nAfter if...\n";
print "model  = $model\n";
print "kernel = $kernel\n";
$
$ # Case 1 : model is "N\A" and kernel has "xen" in it
$
$ perl insania.pl "N\A" abcxenabc
Before if...
model  = N\A
kernel = abcxenabc
 
After if...
model  = Virtual Machine
kernel = abcxenabc
$
$
$ # Case 2 : model is "N\A" and kernel does not have "xen" in it
$
$ perl insania.pl "N\A" abcyenabc
Before if...
model  = N\A
kernel = abcyenabc
 
After if...
model  = N\A
kernel = abcyenabc
$
$
$ # Case 3 : model is not "N\A" and kernel has "xen" in it
$
$ perl insania.pl "M\A" abcxenabc
Before if...
model  = M\A
kernel = abcxenabc
 
After if...
model  = M\A
kernel = abcxenabc
$
$
$ # Case 4 : model is not "N\A" and kernel does not have "xen" in it
$
$ perl insania.pl "M\A" abcyenabc
Before if...
model  = M\A
kernel = abcyenabc
 
After if...
model  = M\A
kernel = abcyenabc
$
$