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--- manipulating_date_strings [2011/11/20 10:40] – juckins
+++ manipulating_date_strings [2022/05/02 11:00] – juckins
@@ Line 16: / Line 16: @@
 [cjuckins@lnxopc2: ~]$ zdump America/Los_Angeles
 America/Los_Angeles  Tue May  3 10:41:52 2011 PDT
+</code>
+Manipulating date/time from NWS text products:
+<code>
+If you take the date/time line from a current text product, such as:
+PM EST TUE 3 JAN 2012
+Add a colon to the hour/minute:
+:06 PM EST TUE 3 JAN 2012
+You can feed that string directly into the linux date command and
+manipulate it forward and backward by any amount of time and then print
+it out in the same format.
+Forward 6 hours:
+$ date --date="8:06 PM EST TUE 3 JAN 2012 6 hours" "+%I%M %p %Z %a %d %b
+%Y" | sed 's/^0//' | sed 's/\s0/ /g' | sed 's/./\u&/g'
+AM EST WED 4 JAN 2012
+Forward 30 minutes:
+date --date="8:06 PM EST TUE 3 JAN 2012 30 minutes" "+%I%M %p %Z %a %d
+%b %Y" | sed 's/^0//' | sed 's/\s0/ /g' | sed 's/./\u&/g'
+PM EST TUE 3 JAN 2012
+Backward 12 hours:
+date --date="8:06 PM EST TUE 3 JAN 2012 -12 hours" "+%I%M %p %Z %a %d %b
+%Y" | sed 's/^0//' | sed 's/\s0/ /g' | sed 's/./\u&/g'
+AM EST TUE 3 JAN 2012
+The 1st sed strips any leading zeros at the beginning of the line, the
+nd sed strips any other leading zeros, and the final sed makes it all
+UPPER.
 </code>
@@ Line 27: / Line 61: @@
 </code>
-Using Linux 'date' to compute a time based upon a given time and some offset value:
+More examples of 'date' to compute a time based upon a given time and some offset value:
 <code>
-[juckins@lightning: /var/www/html/amtrak_status]$ date --date="Sat Nov 19 2011 11:00 pm 30 minutes 2 hours ago"
+[juckins@lightning: ~]$ date --date="sat nov 19 2011 6:00pm"
-Sat Nov 19 21:30:00 EST 2011
+Sat Nov 19 18:00:00 EST 2011
-[juckins@lightning: /var/www/html/amtrak_status]$ date --date="Sat Nov 19 2011 11:00 pm 30 minutes 2 hours"
+[juckins@lightning: ~]$ date --date="sat nov 19 2011 6:00pm 1 hours 1 minutes"
-Sun Nov 20 01:30:00 EST 2011
+Sat Nov 19 19:01:00 EST 2011
+[juckins@lightning: ~]$ date --date="sat nov 19 2011 6:00pm -1 hours -1 minutes"
+Sat Nov 19 16:59:00 EST 2011
+$date --date="yesterday 08:00 gmt" '+%y%m%d/%H%M'
+/0800
+$ date --date="today 18:00 gmt" '+%y%m%d/%H%M'
+/1800
+$ date --date="yesterday 08:00 edt" '+%y%m%d/%H%M'
+/1200
+$ date -d @1446390000
+Sun Nov  1 15:00:00 UTC 2015
 </code>
+Converting from seconds and a different timezone:
+  TZ=":US/Eastern" date -d @1651335000
+  TZ=":America/Phoenix" date -d @1651335000