I have a file name like
filename.txt.zip\_20180202\_30291\_233

In script variable i will have filename in a variable and extension in variable 
like 

```
echo $fileprefix
filename
echo $filesuffix
.txt.zip

```

How do i rename the file to below one ? Moving everything after extension to before extension ? (Note: there could be any numbers after extension )

filename\_20180202\_30291\_233.txt.zip