perl -E 'my @f =("2013-06-01", "fig 1-1", "Fig. 2.2", "Figure. 89-9","Figure 12-8","Figure 1.2"); foreach (@f) { print " $1\n" if /fig(?:ure)?\.?\s(\d+[-.,]\d+)/i; }' 1-1 2.2 89-9 12-8 1.2