Export variables from an .env file

.bashrc

# dotenvexport FILE
#
# Exports all vars from a .env file without overwriting existing variables (see https://docs.docker.com/compose/env-file/)
dotenvexport () {
  FILE=$1
  OLDIFS="$IFS"
  IFS=$'\n'
  for line in $(cat $FILE | grep -vE "^(#|\s*$)"); do
    VAR=${line%%=*}
    if ! [[ -v $VAR ]]; then
      export "$line"
    fi
  done
  IFS="$OLDIFS"
}

# dotenvrun FILE COMMAND [ARG1 ...]
#
# Load all vars from a .env file FILE and run COMMAND with optional arguments.
# The command is run in a subshell so the environment of the currently running 
# shell is not cluttered up.
dotenvrun () {
  FILE=$1
  COMMAND=${@:2}
  (dotenvexport $FILE && bash -c "$COMMAND")
}