vsftpd log file location?

The log file for Ubuntu by default is /var/log/vsftpd.log. The setting is in /etc/vsftpd.conf

The default could be modified by specifying a different pathname (/etc/vsftp.conf entry):

# You may override where the log file goes if you like. The default is shown
# below.                     
#xferlog_file=/var/log/vsftpd.log