gcc -o ftp_server ftp_server.c
gcc -o ftp_client ftp_client.c

./ftp_server <port>

./ftp_client <host> <port>

get     get a file from server.
put     send a file to server.
pwd     get the present directory on server.
dir     list the directory on server.
cd      change the directory on server.
?/help  help to know how to use the commands.
quit    quit client.