search for: smtp_cdb

Greetings Im am not a perl programmer yet I am trying to learn and am debugging someone elses perl run script for use on a centos production box I have and I came across this elif [ -z "${SMTP_CDB:-}" ] Can someone please shed some light on what this eval means in English please? im mainly concerned with the stuff between the two " yet I need all the help I can get what does that say? Im trying to figure out if there is a typo or something in the script. I am not a perl program...