The following switch enables environmental variables to be created and passed to the program.
-set <environment variable>=<value> create and set an environmental variable
Some examples are
ftpshell -script "run.fscr" -set PASSWORD="mypass" #create env variable PASSWORD and set it to mypassftpshell -script "run.fscr" -set SERV_IP="121.122.12.1" #pass env variable. Value can be extracted from the script using getenvvar