Linux Clock
On Linux, the clock generally uses UTC time with a timezone offset in software, as opposed to local time.
Contents
Date and Time
Use date(1) as the root user to set the current date and time.
# January 1st, 2001 at 12:30 sudo date 0101011230
Use hwclock(1) or timedatectl(1) to check the CMOS clock.
Timezone
The configured timezone is set in /etc/localtime. By standard convention, this should be a symbolic link to a pre-prepared file, typically under /usr/share/zoneinfo.
To check the current configuration, try:
realpath /etc/localtime
To change the configuration, try:
ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
For Debian-based distributions, consider using the interactive dpkg-reconfigure tzdata script.
For systemd-capable systems, consider using timedatectl(1).
Some utilities will also respect a TZ environment variable.
export TZ=America/New_York date