This is my row.
2706 abc/efe/efefe/fefe 10143 fefef/dbddf/fvfvdf/vdfvdp 8927 fvdfv/fvdv/fvdfv/fvdfv 11546 fvsddfv/fdfvdv/fvddffv/fvddfv
expected output
2706 abc/efe/efefe/fefe
10143 fefef/dbddf/fvfvdf/vdfvdp
8927 fvdfv/fvdv/fvdfv/fvdfv
.
.
.
.
11546 fvsddfv/fdfvdv/fvddffv/fvddfv
if the format of your row were fixed, you could give this line a try:
cat file|xargs -n2
Test with your example:
kent$ cat f
2706 abc/efe/efefe/fefe 10143 fefef/dbddf/fvfvdf/vdfvdp 8927 fvdfv/fvdv/fvdfv/fvdfv 11546 fvsddfv/fdfvdv/fvddffv/fvddfv
kent$ cat f|xargs -n2
2706 abc/efe/efefe/fefe
10143 fefef/dbddf/fvfvdf/vdfvdp
8927 fvdfv/fvdv/fvdfv/fvdfv
11546 fvsddfv/fdfvdv/fvddffv/fvddfv