[root@localhost ~]# a=123[root@localhost ~]# echo "1" | sed 's/1/"'$a'"/'"123"[root@localhost ~]# ec
.
[root@localhost ~]# a=123
[root@localhost ~]# echo "1" | sed 's/1/"'$a'"/'
"123"
[root@localhost ~]# echo "1" | sed 's/1/'$a'/'
123
[root@localhost ~]# awk 'BEGIN{print '$a'}'
123
[root@localhost ~]# awk 'BEGIN{print '"$a"'}'
123
