date command

to get a formatted date command, just append a + followed by format denotations. Just type in what characters you want to divide the parameters by. Dash, dot, ect...

just give me the year!

# date +%Y
2013

year, month, day...

# date +%Y-%m-%d                                                                                                        ~
2013-08-01

just give me the time!

# date +%H.%M.%S                                                                                                        ~
23.00.20

current date in epoch

$ date +%s
1505537832

date string to epoch

$ date -d '15Sep2017' +%s
1505451600

epoch to human readable date

$ date -d @1505537832 +%Y-%m-%d
2017-09-15