The FTP command APPEND allows you to concatenate a local file to
    a file on a connected remote host. The following command appends
    local file JUL_DEC.DAT to file YEAR.DAT on the connected remote
    host KALI.

    FTP> APPEND JUL_DEC.DAT YEAR.DAT
    200 PORT command successful
    150 Opening data connection for year.dat. (130.180.4.8,1108)
    226 Append transfer complete
    local:large.txt   remote:remote.dat
    15596 bytes sent in 00:00:00.10 seconds (152.30 Kbytes/s)