sed 变量替换 把m.txt文件中的$i替换成$j

zabbix:/root/zabbix# cat a1.sh 
for j in {1..48}
do
   sed   "s/$i/$j/g" m.txt >>tmp.txt
done
You have new mail in /var/spool/mail/root
zabbix:/root/zabbix# cat m.txt | head -20
<item>
                    <name>192.168.4.1-G1/0/$i-in</name>
                    <type>4</type>
                    <snmp_community>zhuyou</snmp_community>
                    <multiplier>1</multiplier>
                    <snmp_oid>interfaces.ifTable.ifEntry.ifInOctets.$i</snmp_oid>
                    <key>1.3.6.1.2.1.2.2.1.10.$i</key>
                    <delay>30</delay>
                    <history>90</history>
                    <trends>365</trends>
                    <status>0</status>