When I read the original article, it didn't seem that making a backup was part of the spec? Therefore: 
# 3456789_123456789_123456789_1234567
perl -pi -e'/^xyz\s*=/&&s/\d+/1+$&/e'

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In reply to Re (tilly) 2: Can anyone make this shorter? by tilly
in thread Can anyone make this shorter? by mlm

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