All good comments so far but you should also use lexical filehandles instead of barewords:

open(FILE, '<', "$confpath/mksysbmachinelist.conf") or die $!;
while(<FILE>){
...
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versus

open( my $fh, '<', "$confpath/mksysbmachinelist.conf" ) or die $!;
while( my $line = <$fh> ) {
...
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The reasons for preferring lexical filehandles instead of bareword are

• barewords are really package variables and those have their own issues
• if another file is all ready open under that package variable, it will be closed.
• if you also have a subroutine named the same, your code will fail silently.

Lexical filehandles have been around since perl 5.6 (2000) but it's only recently (perl 5.8.9) that the perldoc has been updated to reflect that lexicals are really the way to go.