Date (Unix command)

The date command outputs current or specified date and time and can also set the current system time.

Option flags

• +”date format codes” Alters the output using the specified date conversion codes which are prefaced with at % sign. date +”Today is day %j of the year %Y and it’s a %A”

Output: Today is day 078 of the year 2025 and it’s a Wednesday

• -d “datestring” or --date==”datestring” Displays the quoted date. Can be used with the + flag. Date strings consist of calendar date items which express day month and year, and time of day items which express hour:minute:second. Either item group is optional and they may appear in either order. Times and dates can be adjusted using relative item expressions such as + or - time unit as well as keywords such as now, yesterday, tomorrow, previous, next, first and last.

Examples:

       date  -d "Jan 14, 2026 4:33 PM"

       date --date="17:51:02 22/12/2020"

       date -d "next Tuesday +2 years -8 hours + 3 days"

• -f filename or --file=filename where the referenced file contains one of more date strings on separate lines which are converted either to the default date format or the format specified by the + flag. Incompatible with the -d flag.

• -r or --reference=filename - outputs the last modification time of the file

• -s or --set=”datestring” sets the current date and time to the value of datestring. Requires an account with admin privilege.

• -u or --UTC displays Greenwich Mean Time