$ lwp-request -E http://127.0.0.1:80
GET http://127.0.0.1:80
User-Agent: lwp-request/6.15 libwww-perl/6.15

200 Assumed OK
Client-Date: Thu, 16 Jun 2016 23:35:40 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1

Echo: GET / HTTP/1.1
Echo: TE: deflate,gzip;q=0.3
Echo: Connection: TE, close
Echo: Host: 127.0.0.1:80
Echo: User-Agent: lwp-request/6.15 libwww-perl/6.15
Echo:

$ lwp-request -E http://127.0.0.1:80 -HHost:Host
GET http://127.0.0.1:80
Host: Host
User-Agent: lwp-request/6.15 libwww-perl/6.15

200 Assumed OK
Client-Date: Thu, 16 Jun 2016 23:35:42 GMT
Client-Peer: 127.0.0.1:80
Client-Response-Num: 1

Echo: GET / HTTP/1.1
Echo: TE: deflate,gzip;q=0.3
Echo: Connection: TE, close
Echo: Host: Host
Echo: User-Agent: lwp-request/6.15 libwww-perl/6.15
Echo: