Change the vertical logs to horizontal line

Shell Programming and Scripting
1

Hi,

cat log

EPC-SubsId: 3333
EPC-GrIds: RTGHUPA:1:15-11-2013T19:59,22-11-2013T19:59
EPC-GrIds: PrimaXGB_23:10

EPC-SubsId: 4444
EPC-GrIds: RTGHUPB:1:15-11-2013T19:59,22-11-2013T19:59

EPC-SubId: 5555
EPC-GrIds: RTGHUPC:1:15-11-2013T19:59,22-11-2013T19:59

EPC-SubsId: 6666
EPC-GrIds: RTGHUPD:1:15-11-2013T19:59,22-11-2013T19:59
EPC-GrIds: 4PrimaSGB_23:10

I want the results become :

3333 RTGHUPA:1:15-11-2013T19:59,22-11-2013T19:59 PrimaXGB_23:10
4444 RTGHUPB:1:15-11-2013T19:59,22-11-2013T19:59 
5555 RTGHUPC:1:15-11-2013T19:59,22-11-2013T19:59 
6666 RTGHUPD:1:15-11-2013T19:59,22-11-2013T19:59 4PrimaSGB_23:10

Anybody can help ?

Thanks.

2 
$ awk '{printf NF ? $2 OFS : RS}END{printf RS}' file

3333 RTGHUPA:1:15-11-2013T19:59,22-11-2013T19:59 PrimaXGB_23:10 
4444 RTGHUPB:1:15-11-2013T19:59,22-11-2013T19:59 
5555 RTGHUPC:1:15-11-2013T19:59,22-11-2013T19:59 
6666 RTGHUPD:1:15-11-2013T19:59,22-11-2013T19:59 4PrimaSGB_23:10

--edit---

if your log file contains multiple blank line then use this one

$ awk '{printf (NR > 1 && /EPC-Sub/) ? RS $2 OFS : $2 OFS }END{printf RS} ' file