Ubuntu – How to remove the ssh last login info

Is root's home directory encrypted (perhaps by ecryptfs)?

I was having a similar issue where public key authentication would not work unless the user already had an active session. Reading this question, I realized that by choosing to encrypt the user's home directory I was preventing sshd from reading ~/.ssh/authorized_keys unless the user was already logged in on another session (which would then automatically decrypt the home directory).

I resolved the issue by switching to unencrypted home directories, after which public key authentication started working.

When your alias runs ssh ... "cd ...; commands using backquote that I can't easily show on Stack" that commands your shell to run the backquoted ls ... | ... pipeline locally, which finds the name of the newest file in your current directory on your system, and sends that filename as part of the command to the remote system, where of course trying to tail that file doesn't work.

Your options are:

 # ugly quoting to work with doublequotes
 alias logger='ssh ... "cd ...; tail -f \`ls ... | ...\`; bash --login"'

 # shell function or script, which let you use clearer singlequotes 
 logger(){
   ssh ... 'cd ...; tail -f `ls ... | ...`; bash --login'
 }
 # or 
 cat <<"END" >logger # use some dir (early) in $PATH 
 ssh ... 'cd ...; tail -f `ls ... | ...`; bash --login' 
 END
 chmod +x logger

In general you could also provide the command as input to the remote shell instead of a commandline (argument)

ssh ... <<"END" # shouldn't need -t in this case 
cd ...; tail -f `ls ... | ...`
END

but this doesn't combine with your apparent though unmentioned and unexplained desire to leave bash --login running after exiting the tail.

Note the two heredoc cases quote the delimiter string so local shell does NOT subsitute backquote, or certain other things, within the data.

And in all cases it would be better to use the newer $( ... ) syntax for command substitution instead of the old backquote syntax -- especially for questions on Stack where backquotes interfere with (much? most?) non-codeblock formatting.