If for some reason You need a quick and dirty script to retrieve some file from a ftp server, just open your text editor and write some things into your file. Then a simple command line command will download the file You have just write the path.
MS-DOS way:
C:\TMP> TYPE COMMANDFILE.TXT
username
password
dir
get wp-config.php
quit
C:\TMP> FTP -S:COMMANDFILE.TXT ftp.server.name
UNIX/LINUX way:
$ cat test
user username password
dir
get wp-config.php
quit
$ ftp -n ftp.server.name < test