i want to replace the date value in a file. I am using this

date="20060501"
cat file | sed '3,$s/[0-9]*/$date/' > file_tmp
mv file_tmp file

But the output is absurd the date variable is not expanded. How do I expand this variable in sed. Solution in awk will also be preferred.

Thanks in advance

Variables in single quotes are not expanded
try this
sed '3,$s/[0-9]/'$date'/' file > file_tmp