Parse a .env (dotenv) file directly using BASH

parse_dotenv.bash

# Pass the env-vars to MYCOMMAND
eval $(egrep -v '^#' .env | xargs) MYCOMMAND
# … or ...
# Export the vars in .env into your shell:
export $(egrep -v '^#' .env | xargs)

The solution proposed by @arizonaherbaltea will not work correctly when the file is not terminated with a newline. For example using this .env example,

# test.env
MY_VAR=a

Will not work properly, whereas the following will,

# test.env
MY_VAR=a

The only change is adding a newline at the end of the file. This is because read requires a newline to parse the line correctly. Thus, in order to ensure everything works properly we can add a check to see if the file ends with newline and if not append it before parsing it. Doing this will ensure all lines are parsed correctly.

#!/bin/bash

function export_envs() {
  local env_file=${1:-.env}
  local is_comment='^[[:space:]]*#'
  local is_blank='^[[:space:]]*$'
  echo "trying env file: ${env_file}"

  # ensure it has a newline that the end, if it does not already
  tail_line=`tail -n 1 "${env_file}"`
  if [[ "${tail_line}" != "" ]]; then
      echo "No Newline at end of ${env_file}, appending!"
      echo "" >> "${env_file}"
  fi

  while IFS= read -r line; do
    echo "${line}"
    [[ $line =~ $is_comment ]] && continue
    [[ $line =~ $is_blank ]] && continue
    key=$(echo "$line" | cut -d '=' -f 1)
    # shellcheck disable=SC2034
    value=$(echo "$line" | cut -d '=' -f 2-)
    # shellcheck disable=SC2116,SC1083
    echo "The key: ${key} and value: ${value}"
    eval "export ${key}=\"$(echo \${value})\""
  done < <(cat "${env_file}")
}

export_envs ${1}

Then it results,

✗ ./test.sh test.env
trying env file: test.env
The key: MY_VAR and value: a
The key: MY_VAR and value: b

Hope this helps someone out there :)

I've been using shdotenv from @ko1nksm and it's been great.

You can do shdotenv my-command to parse and run a command.
If you want to export the variables to the shell session, use eval $(shdotenv).

What's wrong with:

if [ -f .env ]; then
    set -o allexport
    source .env
fi

Works on macOS with my .env that works with docker compose and does not have quotes around every string.

Test with:

envsubst < "$secret_file" | cat

later in the same script.