shell脚本修改配置文件案例

[root@bigdata01 ~/install]# vim change-yarn-site.sh
#!bin/bash
#此脚本对大数据集群所有节点的yarn-site.xml文件根据集群配置自动更改对应配置。
HOST_LIST=`grep 'bigdata' /etc/hosts |awk '{print $2}'`

conf_dir=/data/software/hadoop/etc/hadoop/yarn-site.xml
vcores=`lscpu |awk 'NR==4{print $2}'`
nodemanager_mb=`free -h |awk 'NR==2{print $2/10*8*1024}'`
#${HOST_LIST[@]}  $@的用法，取出脚本所有参数，带双引号识别为一个整体，不带双引号以空格为分隔，用于循环数组中
scheduler_mb=`for i in ${HOST_LIST[@]} 
do
ssh $i -p 22 -a "free -h" |awk 'NR==2{print $2/10*8*1024}'
done |sort -rn |head -1 |cut -d '.' -f1`

sed -i "/nodemanager/N;s#8#$vcores#g"              $conf_dir
sed -i "/nodemanager/N;s#12288#$nodemanager_mb#g"  $conf_dir
sed -i "/scheduler/N;s#8#$vcores#g"                $conf_dir
sed -i "/scheduler/N;s#9600#$scheduler_mb#g"       $conf_dir


#cut命令使用
[root@bigdata01 /server/scripts]# echo "3.1415926"  |cut -d '.' -f1
3
[root@bigdata01 /server/scripts]# echo "3.1415926"  |cut -d '.' -f2
1415926