I've come across a lot of RBLs and blocklists that sometimes have an instance of weird formatting whether that is missing a newline character or having an extra "space" at the end of the IP. This can break a lot of daemons and firewalls. Here is my safe way of trying to concatenate lists: cat somelist.txt sed s/" "//g|sed -e '$a' >>updatedlist.txt The first sed removes any spaces which is more common than you think........