The Unix date command displays the date and the time of day. The standard output of the date command looks like this:

$ date
Sat Sep 25 14:38:35 PDT 1999

The date command lets you use options to display pieces of the date and time information in a selected format. If you want to display only the day of the month, you would use this command:

$ date +%e
25

Start the format specification with a plus sign. Follow this with one or more percent-sign-marked letters, which indicate which piece of the date you want. The %e represents the day of the month. %b represents the 3-letter abbreviation for the month:

$ date +%b
Sep

$ date +%b-%e
Sep-25