You can also:

while ($fh) {
  /^Confname/ or next;
  work_with $_;
  last;   ## if you want to process only the first ocurrence of such l
+ine
}
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If the lines in the file are not very long, it may fit in memory:

my @confnames = grep /^Confname/, <$fh>;
## if you want to process all lines:
work_with $_ for @confnames;
## else:
work_with $confnames[0];
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Update: Fixed a missing <>. Thanks to Tanktalus!