sed調用shell變量及替換包含關鍵字的整行

#!/bin/bash
##
##
##
SVNAME=hello
NEWNAME=nihao
FILEPATH=/root/a.txt

grep "$SVNAME" $FILEPATH > /dev/null 2>&1
if [ $? -eq 0 ];then
    sed -i 's/^.*'$SVNAME'.*$/'$NEWNAME'/' $FILEPATH
    ## 行內包含“SVNAME”參數，則將整行替換
else
    sed -i '$a'$NEWNAME'' $FILEPATH
    ## 行內不包含“SVNAME”參數，則插入
fi