This count starts at the unix epoch on january 1st 1970 at utc.
Unix timestamp wall clock.
Week numbers weeks by year day numbers days by year years leap years calculate the difference between two dates.
Date and time.
Webkit chrome timestamp unix hex timestamp cocoa core data timestamp mac hfs timestamp sas timestamp seconds days since year 0 bin oct hex converter countdown in seconds epoch clock.
Therefore the unix time stamp is merely the number of seconds between a particular date and the unix epoch.
To compare two dates in bash you can use the unix timestamp value of both date using the date command line or the printf method and a bash if statement with a bash arithmetic expansion or by using a lexicographical comparison of the two dates string by using the double square bracket conditional construct.