One-liner basic CLI for jinja2, context in https://github.com/pallets/jinja/issues/2113

! jinja2_cli_example.sh

echo '{"site": {"hello": "world"}}' > foo.json
echo 'Hello {{ site.hello }}' > foo.txt.j2

bash j2.sh -t foo.txt.j2 -i foo.json -o foo.txt
cat foo.txt

source function.sh
j2 -t foo.txt.j2 -i foo.json -o foo.txt
cat foo.txt
unset -f j2

# can copy-paste the alias definition into ~/.bashrc
source alias.sh
j2 -t foo.txt.j2 -i foo.json -o foo.txt
cat foo.txt
unalias j2

alias.sh

alias j2='python -c '\''import jinja2, argparse, json, sys, os; parser = argparse.ArgumentParser(); parser.add_argument("--input-path", "-i"); parser.add_argument("--output-path", "-o"); parser.add_argument("--template-path", "-t"); args = parser.parse_args(); environment = jinja2.Environment(); print(args.template_path, file = sys.stderr); template = environment.from_string(open(args.template_path).read()); print(args.input_path, file = sys.stderr); ctx = json.load(open(args.input_path)); rendered = template.render(**ctx); print(args.output_path, file = sys.stderr); os.makedirs(os.path.dirname(args.output_path) or ".", exist_ok=True); (open(args.output_path, "w") if args.output_path != "-" else sys.stdout).write(rendered);'\'' '

function.sh

j2() { python -c 'import jinja2, argparse, json, sys, os; parser = argparse.ArgumentParser(); parser.add_argument("--input-path", "-i"); parser.add_argument("--output-path", "-o"); parser.add_argument("--template-path", "-t"); args = parser.parse_args(); environment = jinja2.Environment(); print(args.template_path, file = sys.stderr); template = environment.from_string(open(args.template_path).read()); print(args.input_path, file = sys.stderr); ctx = json.load(open(args.input_path)); rendered = template.render(**ctx); print(args.output_path, file = sys.stderr); os.makedirs(os.path.dirname(args.output_path) or ".", exist_ok=True); (open(args.output_path, "w") if args.output_path != "-" else sys.stdout).write(rendered);' $@; }

j2.sh

python -c 'import jinja2, argparse, json, sys, os; parser = argparse.ArgumentParser(); parser.add_argument("--input-path", "-i"); parser.add_argument("--output-path", "-o"); parser.add_argument("--template-path", "-t"); args = parser.parse_args(); environment = jinja2.Environment(); print(args.template_path, file = sys.stderr); template = environment.from_string(open(args.template_path).read()); print(args.input_path, file = sys.stderr); ctx = json.load(open(args.input_path)); rendered = template.render(**ctx); print(args.output_path, file = sys.stderr); os.makedirs(os.path.dirname(args.output_path) or ".", exist_ok=True); (open(args.output_path, "w") if args.output_path != "-" else sys.stdout).write(rendered);' $@