Example 1. To extract the size in bytes part of the following string
$string = "Document 1342, Microsoft Word - application form-CUHK.doc
owned by CLGSONG was printed on cclcgo4 via port 155.69.50.247:RAW.
Size in bytes: 531829; pages printed: 0"
$bytes = $string;
$bytes =~ s/.*Size.in.bytes[:].(.*)[;].*//;
print $bytes;