Find specific pattern and print complete text block using awk or sed

Question

How can find a specific number in a text block and print the complete text block beginning with the key word \"BEGIN\" and ending with \"

Answer 1

perl -lne 'if(/56789/){$f=1}
           push @a,$_;
           if(/END/){
              if($f){print join "\n",@a}
           undef @a;$f=0}' your_file