snmpget $device .1.3.6.1.2.1.2.2.1.2.$interface

Perl is not a shell script interpreter. Assuming this is a command line for a program you need to call, you need to make it a string, and actually execute it, either by system or by backticks(``) or qx. Plus, it needs a semicolon between statements.

So, start by changing this line to

`snmpget $device .1.3.6.1.2.1.2.2.1.2.$interface`;
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or

system("snmpget $device .1.3.6.1.2.1.2.2.1.2.$interface");
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depending on what you want to do with the output.

I don't know this particular protocol so you'll probably have to tweak it some more before it actually becomes usable.