It seems everything has its own idea of what a timestamp is. For example, I use Firefox most of the time. It keeps track of all kinds of things that I do. If I look in its places database
$ sqlite3 ~/.mozilla/firefox/xjici1nz.default/places.sqlite sqlite> .tables moz_anno_attributes moz_favicons moz_items_annos moz_annos moz_historyvisits moz_keywords moz_bookmarks moz_hosts moz_places moz_bookmarks_roots moz_inputhistory sqlite> .headers on sqlite> select * from moz_places; id|url|title|rev_host|visit_count|hidden|typed|favicon_id|frecency|last_visit_date|guid|foreign_count ...
I can see lots of places I've visited.
sqlite> select url, last_visit_date from moz_places limit 3; url|last_visit_date https://www.mozilla.org/en-US/firefox/central/| http://www.ubuntu.com/|1461414650785039 http://wiki.ubuntu.com/|
One column is called "last_visit_date," but it doesn't look like a date; it's just a big number. Apparently, I visited www.ubuntu.com at 1461414650785039. Maybe it's a Unix date.
$ date -d @1461414650785039 Wed Sep 19 21:57:19 EST 46312356
Nope, that's some time after the Sun has exploded. What does it mean? Well, it turns out that Mozilla time is the same as Unix time, except it's measured in microseconds instead of seconds. With this module, we can convert that database entry into a standard datetime
$ perl -MTime::Moment::Epoch -E 'say Time::Moment::Epoch::mozilla("1461414650785039")'
2016-04-23T12:30:50.785039Z
So apparently I visited on April 23rd of this year, not some time in the distant future.
Sometimes I use Chromium. It keeps track of all kinds of things that I do too. If I look in its History database
$ sqlite3 ~/.config/chromium/Default/History sqlite> .tables downloads meta urls downloads_url_chains segment_usage visit_source keyword_search_terms segments visits sqlite> .headers on sqlite> select * from urls; id|url|title|visit_count|typed_count|last_visit_time|hidden|favicon_id ... sqlite> select url, last_visit_time from urls limit 3; https://github.com/oylenshpeegul/Epochs-perl|13106714670814172 https://github.com/oylenshpeegul?tab=repositories|13106714667811541 https://github.com/oylenshpeegul|13106714667342966
I see I last visited this website at 13106714670814172. When was that?
$ date -d @13106714670814172 Mon Nov 20 13:09:32 EST 415337223
Again, some crazy time in the future?
$ perl -MTime::Moment::Epoch -E 'say Time::Moment::Epoch::chrome("13106714670814172")'
2016-05-03T02:04:30.814172Z
No, it was just a little while ago. Chromium measures time in microseconds also, but instead of starting at 1970, it starts at 1601. But you don't have to remember that because Time::Moment::Epoch does.
Firefox and Chromium times are just two examples. This module knows a bunch more (apfs, chrome, cocoa, dos, google_calendar, icq, java, mozilla, ole, symbian, unix, uuid_v1, windows_date, windows_file). If you know any others, please let me know!
There are similar modules written in other languages:
Pull requests welcome!