Load environment variables from dotenv / .env file in Bash

load_dotenv.sh

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

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

thank you this was better

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
)"

env $(cat .env)
this does not work for me but this one works

env $(cat .env|xargs) CMD

my .env has some special value such as FOO='VPTO&wH7$^3ZHZX$o$udY4&i'
@NatoBoram

A simple solution that works for bash, zsh, and fish:

eval export $(cat .env)

Use this to create the file

export -p > .env

and just

. .env

to read it back in

From man export:

The shell shall format the output, including the proper use of quoting, so that it is suitable for reinput to the shell as commands that achieve the same exporting results

Although set -a; source .env; set +a is elegant and short, one feature which I missed is this overwrite existing exported variables.
I my use case I have a script, which connects to postgres with a predefined user. This user is stored in .env file as PG_USER=myuser. So the script does the magical set -a; source .env; set +a and everything works. But sometimes I need ad-hoc change the user. So what I'd do is PG_USER=postgres ./my_script.sh. In order not to over write the existing var I did this horrendous piece of code:

IFS=$'\n'
for l in $(cat /etc/my_service/.env); do
    IFS='=' read -ra VARVAL <<< "$l"
    # If variable with such name already exists, preserves it's value
    eval "export ${VARVAL[0]}=\${${VARVAL[0]}:-${VARVAL[1]}}"
done
unset IFS

The cleanest solution I found for this was using allexport and source like this

set -o allexport
source .env set
+o allexport

This was by far the best solution here for me, removed all the complexity around certain chars, spaces comments etc. Just needed a tweak on formatting to prevent others being tripped up, should be:

set -o allexport source .env set +o allexport

work like a charm. ty

this read line by line, allowing to use previous set variables

  while read -r LINE; do
    if [[ $LINE == *'='* ]] && [[ $LINE != '#'* ]]; then
      ENV_VAR="$(echo $LINE | envsubst)"
      eval "declare $ENV_VAR"
    fi
  done < .env

this was working the best for me but this still has 2 problems

1. code breaks if the value has () characters inside it
2. can not be used inside a function

here is my solution:

read_env() {
  local filename="${1:-.env}"

  if [ ! -f "$filename" ]; then
    echo "missing ${filename} file"
    exit 1
  fi

  echo "reading .env file..."
  while read -r LINE; do
    if [[ $LINE != '#'* ]] && [[ $LINE == *'='* ]]; then
      export "$LINE"
    fi
  done < "$filename"
}