There are a substantial number of commands available for users to establish their bona-fides on remote systems and to navigate the remote system's file system. A long reply may be sent as several messages with a dash after the three digits on the first message and no dash after the three digits on the last message. Here is a list of all commands. The ones marked with an asterisk are rare and rarely implemented. String Meaning ABOR Abort transfer.
Some systems associate both accounts and users with file system objects.
ALLO Allocate space for file about to be sent. Parameter specifies number of bytes. APPE Append file to existing file. CDUP Change to parent directory on remote system. CWD Change working directory on remote system.