+> Pattern selection and interpretation:

Navigate to folder /var/log/syslog, grep to search for text in syslog.

grep -w <username> /var/log/syslog

For some cases, if you want to search alongside <username> the and contain uppercase and lowercase, here is the syntax.

grep -i <username> /var/log/syslog

+> Output control:

grep -a <text> /var/log/syslog