In Linux sftp allows to specify username along with the URL like this:
$ sftp username@host
However, ftp does not support such a feature. This makes it hard since one needs to remember bunch of usernames for each server. And some are so unintuitive to memorize. If a secure machine is used, not a 24/7 the Internet connected server, still there is a way to workaround the problem using switch -n.
What has to be done is to edit/create .netrc file of/to the user home directory and add an entry like this:
machine hostaddress
login username
Then save the file and run ftp command like this:
$ ftp host
After that the ftp command picks up the username matches the host address from .netrc file and no longer requires for username, just prompts for password.
It is also possible add password to .netrc file like this:
machine hostaddress
login username
password password
I highly recommend against of it. It is insecure and if the system gets hack, all the credentials will be available to the crackers.
.netrc supports multiple entries, similar to following:
machine hostaddress1
login username1
machine hostaddress2
login username2
