Is there a way to return the value of the environment variable RAILS_ENV from the Linux command line?

Question

In Linux, you can find the value of the

$PATH

environment variable with the command

echo $PATH

. In Rails,

RAILS_ENV

(and the similar

RACK_ENV

) is an environment variable with values such as "development" and "production". But on the command line,

echo RAILS_ENV

returns the unhelpful string

RAILS_ENV

(as you'd expect) and

echo $RAILS_ENV

returns nothing (presumably because that's not what the environment variable is called). I've also tried

env RAILS_ENV

and variants. Am I getting the syntax wrong, or what?

Am I right to think that basically the environment variable just doesn't exist until Rails is run? Well...I tried running a Rails server in one terminal, then opened another and then repeated the above commands; no dice.

Or is the problem that Linux, or my shell, doesn't track this environment variable? But...wouldn't it have to, being an environment variable? I tried looking for it in the output of the

env

command, and it's not there.

Is it possible that the only way to discover the value of the

RAILS_ENV

environmental variable is through Rails itself, e.g., by calling

Rails.env

?

UPDATE: this helpful discussion gives the command

rails r "puts Rails.env"

, but I was looking for a command that didn't call Rails itself.

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Answer 1

You were right with echo $RAILS_ENV. It is likely not set, so it is defaulting to development. This is done within the Rails codebase.

$ export RAILS_ENV=development
$ echo $RAILS_ENV #=> development

In another console

# In a new window
$ echo $RAILS_ENV
$ rails runner "puts Rails.env" #=> development
$ RAILS_ENV=test rails runner "puts Rails.env" #=> test

No RAILS_ENV variable is set, to rails defaults to development

Here is the equivilent in Bash.

if [ -z "$RAILS_ENV" ]; then
  export RAILS_ENV="development";
fi
echo $RAILS_ENV

Is there a way to return the value of the environment variable RAILS_ENV from the Linux command line?

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