error while executing lua script for redis server

Question

I was following this simple tutorial to try out a simple lua script

http://www.redisgreen.net/blog/2013/03/18/intro-to-lua-for-redis-programmers/

I created a simple hello.lua file with these lines

local msg = "Hello, world!"
return msg

And i tried running simple command

EVAL "$(cat /Users/rsingh/Downloads/hello.lua)" 0

And i am getting this error

(error) ERR Error compiling script (new function): user_script:1: unexpected symbol near '$' 

I can't find what is wrong here and i haven't been able to find someone who has come across this.

Any help would be deeply appreciated.

Answer 1

Your problem comes from the fact you are executing this command from an interactive Redis session:

$ redis-cli
127.0.0.1:6379> EVAL "$(cat /path/to/hello.lua)" 0
(error) ERR Error compiling script (new function): user_script:1: unexpected symbol near '$'

Within such a session you cannot use common command-line tools like cat et al. (here cat is used as a convenient way to get the content of your script in-place). In other words: you send "$(cat /path/to/hello.lua)" as a plain string to Redis, which is not Lua code (of course), and Redis complains.

To execute this sample you must stay in the shell:

$ redis-cli EVAL "$(cat /path/to/hello.lua)" 0
"Hello, world!"