Receive a time stamp from input in a shell script

Question

I am working on a script that receives two inputs:

1. timeZone (America/Los_Angeles)
2. a time stamp in UTC with the following format "%Y-%m-%dT%H:%M:%SZ”)

The script is supposed to find the offset and add it to the input timestamp, so when I run:

./TZ-converst.sh Asia/Kolkata 2016-12-07t00-00-00z

the output will be 2016-12-07t00-05-30z.

The offset for each timezone comes easily:

offset="$(TZ=":$tz" date +%z )"

However, I am having a hard time adding this offset to the input time "2016-12-07t00-00-00z".

I am trying to use date -d to use the input parameter but I keep getting

"usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...[-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]"

Any thoughts?

Answer 1

Print Time Zone Offset, according to summer time derivation, at a specific time:

TZ=Asia/Kolkata date -d '2016-12-07t00:00:00z' +%z
+0530

Care to keep syntax:

Year - Month - Day t Hours : Minutes : Seconds z