/pattern/../pattern/

べんりかもなぁ。。

#こういうファイルを入れると
=pod
this is 1 and next
this is 2 and next
this is 3 and next
this is 4 and next
this is 5 and next
this is 6 and next
this is 7 and next
this is end and next
this is after 1
this is after 2
=cut


while(<>){
  if(/2/../4/){
    print;
  }
}


#こうなる
=pod
this is 2 and next
this is 3 and next
this is 4 and next
this is after 2
=cut


#/pattern/.../pattern/
#...もあって動作が違うとかなんとか