sed awk 练习

#定位到某一行 添加内容
lower_case_flag=`cat /etc/my.cnf|grep "^lower_case_table_names"` if [ "X" == "X${lower_case_flag}" ] then line=`sed -n "/max_connections=/=" /etc/my.cnf |tail -n1` echo "location [max_connections] line:${line}" sudo sed -i "${line}s/.*/lower_case_table_names=1\n&/" /etc/my.cnf else echo "lower_case_table_names=1 is exist,not need set." fi

#替换
sed -i "s/pattern/modify/g"  file

#替换整行

sed -i '/pattern/creplace' file  

 

#删除匹配行
sed '/pattern/d' file   例：删除空包行 sed '/^$/d' file

 

$NF表示取最后一个域   
# filename=/opt/file
fileabs=$(echo $filename |awk -F/ '{print $NF}')