yun缓存软件包
#!/bin/bash packagename=$1 which yumdownloader || yum install -y yum-utils &>/dev/null ls /bak/pkg || mkdir -p /bakpkg yumdownloader --resolve --destdir=/bakpkg/ $packagename
CDIR="$(cd "$(dirname "$0")" ; pwd -P)" #上一层路径 NDIR="./$CDIR/.."