Time

Run the date command to get the current time. If the user gives a timezone argument, convert it and pass it via TZ.

No argument (machine's local time)

date

Argument given

Accept two input styles:

1. UTC offset, e.g. utc+7, UTC-5, gmt+8
   • Parse the sign and number (e.g. +7, -5)
   • Map to POSIX Etc/GMT zones — note the sign is inverted: UTC+7 → Etc/GMT-7, UTC-5 → Etc/GMT+5

   TZ='Etc/GMT-7' date   # for utc+7