The date command

Summary

The date command sets and shows the system date and time.

Basic command structure

For all descriptions below, the dollar sign indicates that BASH command prompt.

$ date [options] [+format]

Note: If no option or format is given then the ‘date’ command will print the current locale’s date and time.

Possible Flags

-d

The -d flag displays the given date/time string. The date displayed can be given as a word: today, yesterday, etc. or as a phrase: “Jan 12 2012”

-r

The -r flag displays the time when a specified file was last modified. Use the filename or path/to/filename.

-s

The -s flag sets the system date and time. That being so, it also requires superuser privileges. Use “YYYY-MM-dd HH:MM:SS”

-u

The -u flag shows the date/time in UTC instead of the local timezone.

Output options

The date command has many different kinds of outputs as described below:

• Standard output with no flags or +formats, which displays the local date and time of the system.

• Output with -r gives the last modification date of a file within the directory.

• Output with [+format] adjusts what part of the time or date is displayed. For example +%Y outputs the year (YYYY), +%m outputs the month (MM), and %d (dd) outputs the day.

Examples

• If you wanted to check the last modification date of a file, but in the MM/DD/YY format run $ date -r path/to/filename +%D.
• If you want to see the time as the 12-hour format, as opposed to the standard use of 24 hours, run $ date +"%I %p".

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