10

I've been using docker for a while and there's a command I write each time I boot up my docker:

eval $(docker-machine env)

I know eval shouldn't be used unless necessary, but it's mentioned by the following:

docker-machine env outputs environment variables like this:

docker-machine env
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://<some_ip>:<some_port>"
export DOCKER_CERT_PATH="/home/gableroux/.docker/machine/machines/default"
export DOCKER_MACHINE_NAME="default"
# Run this command to configure your shell: 
# eval $(docker-machine env)

eval grabs these and load them in my current session.

Now what if I'd like to have an alias like this:

alias dockereval="eval $(docker-machine env)"

Syntax is good, but the problem is when a dotfile (let's say .zshrc as an example), well the content of the $() is evaluated when registering the alias when you source that file.

which dockereval

Results in

dockerenv: aliased to eval

I tried a few things like:

alias dockereval="docker-machine env | eval"
alias dockereval="docker-machine env | /bin/bash"
alias dockereval="eval `docker-machine env`"

but none did work. 2nd one is probably because it's running in a different session, 3rd does the same as $() I guess

Is there an other way to load these environment variables with an alias?

GabLeRoux
  • 885
  • 9
  • 17
  • 1
    Use single-ticks (`'`) in your alias definition so that the subshell is created and parsed each time you execute it rather then when you define the alias. – DopeGhoti Jun 08 '16 at 18:50
  • An alternate solution would be to use a function instead of an alias. I now prefer this to alias as I keep syntax highlighting and can split those magic shortcuts into multiple lines. – GabLeRoux Oct 19 '18 at 12:38

1 Answers1

18

Enclose your alias in single quotes instead of double quotes.

alias dockereval='eval $(docker-machine env)'

Double quotes allow expansion of variable (in bash at least) while single quotes don't

Hesham Ahmed
  • 544
  • 3
  • 9