$ jinja2 helloworld.tmpl data.json --format=json
$ cat data.json | jinja2 helloworld.tmpl
$ curl -s https://httpbin.org/ip | jinja2 helloip.tmpl
$ curl -s https://httpbin.org/ip | jinja2 helloip.tmpl > helloip.html

Usage: jinja2 [options] <input template> <input data>
Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  --format=FORMAT       format of input variables: auto, ini, json,
                        querystring, yaml, yml
  -e EXTENSIONS, --extension=EXTENSIONS
                        extra jinja2 extensions to load
  -D key=value          Define template variable in the form of key=value
  -s SECTION, --section=SECTION
                        Use only this section from the configuration
  --strict              Disallow undefined variables to be used within the
                        template