The same process that declared a variable will also report an error! about esh HOT 1 CLOSED

You didn’t export these variables, so they cannot get into esh process, obviously. That’s how the shell works.

You can either pass the variables as arguments to esh (as explained in --help):

esh ./template/nginx.tpl.esh backend_url=1 location=2

or use shell’s feature to pass environment variables for a command:

backend_url=1 location=2 esh ./template/nginx.tpl.esh

or export variables before executing esh:

export backend_url=1
export location=2
esh ./template/nginx.tpl.esh

from esh.