What does “-e” do inside an expression in Perl?

Question

I ran into this piece of code:

unless(-e $SNMPWALK)
{
    print \"snmpwalk is not installed!\\n\";
    exit 3;
}

What is the function of <

Answer 1

It's one of the file test operators. In this case it tests whether the file whose name is in $SNMPWALK exists

It's documented in perlfunc under perldoc -X