Format/result | Command | Output

--------------------------------+----------------------------+------------------------------

YYYY-MM-DD | date -I | $(date -I)

YYYY-MM-DD_hh:mm:ss | date +%F_%T | $(date +%F_%T)

YYYYMMDD_hhmmss | date +%Y%m%d_%H%M%S | $(date +%Y%m%d_%H%M%S)

YYYYMMDD_hhmmss (UTC version) | date --utc +%Y%m%d_%H%M%SZ | $(date --utc +%Y%m%d_%H%M%SZ)

YYYYMMDD_hhmmss (with local TZ) | date +%Y%m%d_%H%M%S%Z | $(date +%Y%m%d_%H%M%S%Z)

YYYYMMSShhmmss | date +%Y%m%d%H%M%S | $(date +%Y%m%d%H%M%S)

YYYYMMSShhmmssnnnnnnnnn | date +%Y%m%d%H%M%S%N | $(date +%Y%m%d%H%M%S%N)

YYMMDD_hhmmss | date +%y%m%d_%H%M%S | $(date +%y%m%d_%H%M%S)

Seconds since UNIX epoch: | date +%s | $(date +%s)

Nanoseconds only: | date +%N | $(date +%N)

Nanoseconds since UNIX epoch: | date +%s%N | $(date +%s%N)

ISO8601 UTC timestamp | date --utc +%FT%TZ | $(date --utc +%FT%TZ)

ISO8601 UTC timestamp + ms | date --utc +%FT%T.%3NZ | $(date --utc +%FT%T.%3NZ)

ISO8601 Local TZ timestamp | date +%FT%T%Z | $(date +%FT%T%Z)

YYYY-MM-DD (Short day) | date +%F\(%a\) | $(date +%F\(%a\))

YYYY-MM-DD (Long day) | date +%F\(%A\) | $(date +%F\(%A\))