[root@asmboy ~]# more tes
1 sldj
1 sldfjf
2 lsdf
1 sdsl
2 ls
[root@asmboy ~]# awk '$1==1{if(i++)printf ","$2;else printf $2}END{print ""}' tes
sldj,sldfjf,sdsl
[root@asmboy ~]# awk '$1==2{if(i++)printf ","$2;else printf $2}END{print ""}' tes
lsdf,ls