root@BJ-CentOS7 ~ # cat ip.txt 61.151.163.73 180.163.22.108 101.91.24.25 101.91.24.37 root@BJ-CentOS7 ~ # cat ip.txt | awk -F "." -v OFS='.' '{print $1,$2,$3,"0/24"}' | sort | uniq 101.91.24.0/24 180.163.22.0/24 61.151.163.0/24 root@BJ-CentOS7 ~ #