gistfile1.txt

## Creating a sample git repo with one commit (I'm in timezone +0300 Europe/Moscow)

bessarabov@air:~$ mkdir sample
bessarabov@air:~$ cd sample/
bessarabov@air:~/sample$ git init .
Initialized empty Git repository in /Users/bessarabov/sample/.git/
bessarabov@air:~/sample$ touch a
bessarabov@air:~/sample$ git add a
bessarabov@air:~/sample$ git commit -m 'Initial commit'
[master (root-commit) 2afbb55] Initial commit
 1 file changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 a
bessarabov@air:~/sample$ date
Mon Jul 15 21:28:38 MSK 2019
bessarabov@air:~/sample$


## Check that --date=iso & --date=iso-local return the same time (because I'm in the same timezone that the commit author)

bessarabov@air:~/sample$ git log --date=iso
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 21:28:34 +0300

    Initial commit
bessarabov@air:~/sample$ git log --date=iso-local
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 21:28:34 +0300

    Initial commit
    
## I'm changing my timezone to UTC and see that --date=iso & --date=iso-local return different times (and --date=iso shows the time that was on the wallclock of the author) 

bessarabov@air:~/sample$ TZ=UTC git log --date=iso
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 21:28:34 +0300

    Initial commit
bessarabov@air:~/sample$ TZ=UTC git log --date=iso-local
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 18:28:34 +0000

    Initial commit
    
## The same as the previous one, but using different timezone (--date=iso shows the time that was on the wallclock of the commit author)

bessarabov@air:~/sample$ TZ='America/New_York' git log --date=iso
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 21:28:34 +0300

    Initial commit
bessarabov@air:~/sample$ TZ='America/New_York' git log --date=iso-local
commit 2afbb5572c1b75015505016898304ccc8f4ceb5c (HEAD -> master)
Author: Ivan Bessarabov <ivan@bessarabov.ru>
Date:   2019-07-15 14:28:34 -0400

    Initial commit