lftp: login, put file in remote dir and exit in a single command: proper quoting help

$ lftp -c "open -u user,pass ftpsite.com; put -O remote/dir/ /local/file.txt" 

should do it.

If this doesn't work try adding to your /etc/lftp.conf the following lines:

set ftp:ssl-protect-data true
set ftp:ssl-force true
set ftp:ssl-auth TLS
set ssl:verify-certificate no

lftp -e "put -O remote/dir/ /local/file.txt; bye" -u user,pass ftpsite.com