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)

I wrote my own because was using forbidden symbols in envs.

This basically adds apostrophes so that all variables will be treated as strings. This way you can use your Docker env files and source them with source envs.sh

import sys


def main(input_path, postfix='.sh'):
    with open(input_path, 'r') as file_handle:
        lines = file_handle.readlines()
        envs = {}
        for line in lines:
            try:
                parts = line.split('=')
                name = parts[0]
                value = ''.join(parts[1:]).rstrip('\n')
            except ValueError:
                pass
            else:
                envs[name] = value

    output_path = f'{input_path}{postfix}'
    with open(output_path, 'w') as file_handle:
        lines = []
        for name, value in envs.items():
            line = f'{name}=\'{value}\'\n'
            lines.append(line)
        file_handle.writelines(lines)


if __name__ == '__main__':
    # Passes first argument as input path.
    main(sys.argv[1])

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.