Load environment variables from dotenv / .env file in Bash

load_dotenv.sh

if [ ! -f .env ]
then
  export $(cat .env | xargs)
fi

I had troubles with a (Docker) setup where environment variables had spaces in their value without quotes and I needed to get the container's env. vars. in a script called during the container execution/runtime.

I ended getting the variables in the entrypoint, exporting them to a file and them reading them when needed.

# In entrypoint
export -pn \
    | grep "=" \
    | grep -v -e PATH -e PWD -e OLDPWD \
    | cut -d ' ' -f 3- \
    > /docker-container.env

The export command fixes issues with missing quotes, avoiding errors where the shell interpreter tries to execute parts of the variable value as commands.

# In script
set -o allexport
. /docker-container.env
set +o allexport

(I had to use /bin/sh so not using source file but . file)

oh-my-zsh users can also activate the dotenv plugin.

Fantastic! Thanks @n1k0!

Posix compliant version built around set, [ ] and . Many thanks to the prior posters who brought up set -o a and set -a / set +a

This snippet will source a dotenv file, exporting the values into the environment. If allexport is already set, it leaves it set, otherwise it sets, reads, and unsets.

if [ -z "${-%%*a*}" ]; then
    set -a
    . ./.env
    set +a
else
    . ./.env
fi

double brackets [[, source, setopt are not available in posix. Nor is the test [[ -o a ]] to check for set options. And we need to quote our comparison strings to deal with empty vars.

The code to check if an option is set is a bit of a pain. It could be a case statement or a grep on set -o like set -o | grep allexport | grep -q yes, but blech. Instead I've used parameter expansion with pattern matching to remove a maximum match from the $- variable containing a single line of the set options.

${-%%*a*} uses %% parameter expansion to remove the longest suffix matching the pattern *a*. If $- contains a then this expansion produces and empty string which we can test with -z or -n.

subtle bug if no options are set, so the comparison "$-" = "${-%%a*}" will check that the expansion changed the string. allexport is set if the two strings differ. And even % will work as we don't need a maximal match and can remove the leading * from our pattern match.

if [ "$-" = "${-%a*}" ]; then
    # allexport is not set
    set -a
    . ./.env
    set +a
else
    . ./.env
fi

When the values have newline chars \n, spaces or quotes, it can get messy.

After a lot of trial and error, I ended up with a variation of what @bergkvist proposed in https://gist.github.com/mihow/9c7f559807069a03e302605691f85572?permalink_comment_id=4245050#gistcomment-4245050 (thank you very much!).

ENV_VARS="$(cat .env | awk '!/^\s*#/' | awk '!/^\s*$/')"

eval "$(
  printf '%s\n' "$ENV_VARS" | while IFS='' read -r line; do
    key=$(printf '%s\n' "$line"| sed 's/"/\\"/g' | cut -d '=' -f 1)
    value=$(printf '%s\n' "$line" | cut -d '=' -f 2- | sed 's/"/\\\"/g')
    printf '%s\n' "export $key=\"$value\""
  done
)"