I have a file like:http://example.mxhttps://test.comhttp://4.3.4.4http://dev.somedomain.comhttp://1.3.4.2I want to get rid of the ones with IPs so that the result should be:http://example.mxhttps://test.comhttp://dev.somedomain.comWhat I did is:cat  in.log |  sed  '/^http:\/\/[0-9]/d'  > out.logBut it does not work. 
How to remove lines containing IP address?
text processing;sed;ip address
But it does work.   The correct answer appears to be already in your question.$ cat in.loghttp://example.mxhttps://test.comhttp://4.3.4.4http://dev.somedomain.comhttp://1.3.4.2$ cat  in.log |  sed  '/^http:\/\/[0-9]/d'  > out.log$ cat out.loghttp://example.mxhttps://test.comhttp://dev.somedomain.com$