regular expression in a variable

[Curt Shaffer]

I need to set a variable to a filename where only 1 section of the file is
static. 

 

For example:

 

$filename =~ /test/;

 

Where the following:

 

Print "$filename\n";

 

Would produce:

 

123test456.txt

 

The only way I see this being possible is with regular expressions but I
can't for the life of me figure out the syntax I need. 

 

Any help appreciated!

 

Curt