# date
# ls /usr/share/zoninfo/Asia
# mv /etc/localtime /etc/localtime_org
# ln -s /usr/share/zoneinfo/Asia/Seoul /etc/localtime
# date
# timedatectl
# cal
# cal 2023
# cal 2025
# cal
# clear
# history
# clear
# logname
# users
# who
# whoami
# logname
# users
# who
# uname
# uname -a
# uname -m
# uname -n
# uname -r
# uname -s
# uname -v
# hostname
# arch
# env
# echo Have a good time
# echo -e Have a god time. "\n" Nice good day.
# which echo
# which cp
# which mv
# ls /usr/bin
# history
# !25
# history -d 25
# history -c
# history
# !3
# history -d 5
# history -c
# su - root
# su - cskisa
# pwd
# ls -F
# ls -F /usr