read and check for missing .env variables

greg 0
Viewed 60

I have a .env file with those vars:

REACT_APP_API_URL=https://my-enpoint.com/api 
REACT_APP_APP_URL=https://my-app.com
ESLINT_NO_DEV_ERRORS=true
REACT_APP_PUSHER_APP_KEY=d83519e4-6017-41f4-b8b2-6093f6480914

...etc

I would like to check if any of the variables are missing and print info about missing value in specified variable.

I've tried to read a variables from file in loop but I cannont access to them in loop. Manually its possible, by getting variable one by one. But I want to do it automatically. My code:

VARIABLES=("REACT_APP_URL" "REACT_APP_API_URL" "ESLINT_NO_DEV_ERRORS" "REACT_APP_PUSHER_APP_KEY")
source .env
for i in "${!VARIABLES[@]}"; do
  env -S "$(cat .env)" sh -c 'echo '${VARIABLES[$i]}"'
done

I have zero exp in bash but I need to make some basic automation in my project

environment-variables bash linux
2 Answers

The code you’ve posted goes in the right direction but it does many incorrect things and hence doesn’t work:

  1. You don’t need to (and should not) source the environment file.
  2. Your code is iterating over the indices of the array VARIABLES; why not iterate directly over the values? This simplifies the code.
  3. The -S flag of env doesn’t fulfil a purpose here.
  4. Single-quoting the command that we pass to env prevents parameter expansion. This means that the command doesn’t actually see the current variable.
  5. Passing the contents of the file as command line arguments to env unfortunately won’t work — it will just concatenate all variables into a single line. You can avoid this by not quote the substitution, but then it won’t work if any of the values in the .env file contains spaces, which is unacceptable.

The last point can probably be solved by some clever trickery involving xargs but the resulting code is non-portable. It’s much easier to simply source the file inside the command that’s executed by env.

Lastly, why are we using env at all here? Why not just run sh -c directly? — Because we want to only look at variables that are defined inside .env. But the code currently doesn’t do that! To do this, we need to pass -i (or --ignore-environment) to env — in other words: ignore the current environment.

Putting all this together:

variables=(REACT_APP_URL REACT_APP_API_URL ESLINT_NO_DEV_ERRORS REACT_APP_PUSHER_APP_KEY)

for var in "${variables[@]}"; do
  env -i sh -c "source ./.env; echo \"\$$var\""
done

Some comments:

  1. By convention, ALL_CAPS is reserved for environment variables. We use lowercase for our non-environment variables.
  2. You don’t need to quote string literals without special characters (i.e. the values of the variables array).
  3. We need to pass a path name (./.env) to source; only using a filename (.env) does not work, since source then searches the (unset) $PATH locations.
  4. Don’t forget to quote all expansions! This includes quoting inside the sh -c command, hence \"\$$var\": the backslashes allow nesting the quotation marks (and escape the initial $ so that the command sees an environment variable name).

This code prints all variables defined in .env. If you want to instead test whether they’re set, use the following:

for var in "${variables[@]}"; do
  env -i sh -c "source ./.env; test -v $var || echo \"$var is unset!\""
done
Konrad Rudolph0

Something like this may help:

a=1
b=
c=3

vars=(a b c)

for var in ${vars[@]}; {
    [[ ${!var} ]] || echo $var is empty
}

Or use grep to check your file:

$ cat env
a=1
b=
c=3

$ vars=$(grep -Ev '(a|b|c)=.+' env)
$ [[ $vars ]] && echo $vars not set
b= not set

To autocheck all vars in env file:

grep -Ev '.+=.+' env
b=
usertNTQ0
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