Use . instead of source in shell scripts

[gucharbon]

I'm using 18.04.3 LTS (Bionic Beaver) and python 3.7.5
I just created my own repository using cookiecutter.

I ran the script ./scripts/build-push.sh and received the error below:

(venv) [email protected]:/c/Users/monsoon/fastapi/webdemo(21:19:57)$ ./scripts/build-push.sh
./scripts/build-push.sh: 6: ./scripts/build-push.sh: source: not found

After taking a look at the template I saw that /bin/sh is specified in shebang:

#! /usr/bin/env sh

# Exit in case of error
set -e

Ubuntu uses /bin/dash in place of/bin/sh and not /bin/bash. Ubuntu Wiki states that:

The source builtin is a bashism (related checkbashisms warning text: 'source' instead of '.'). Write this simply as . instead.

Isn't there anybody on Ubuntu or Debian which tried to run the scripts and had this error? I searched existing issue but found none.

Edit: I just saw in the README that user should use bash to start scripts (as in the example: TAG=prod FRONTEND_ENV=production bash ./scripts/build-push.sh) but I still feel that this . should be used instead of source to be coherent with shebang and to allow usage of TAG=prod FRONTEND_ENV=production ./scripts/build-push.sh.

Anyway thanks for the awesome work :)

[Shackelford-Arden]

@gucharbon While that documentation you provided does indicate the use of dash on Ubuntu based systems, if you run the command as shown in the shebang:

/usr/bin/env sh

On an Ubuntu system (tested on Ubuntu 18.04.4) you'll find that this works just fine.

As the documentation page you referenced indicates in the second paragraph from the top:

The default login shell remains bash. Opening a terminal from the menu or shortcut [crtl-alt-t] provides interactive bash. A script run from the desktop or file manager, through the dialogue 'run in terminal' will execute as POSIX dash.

The default shell is still bash.

The benefit of specifying the /usr/bin/env sh at the beginning tells the system to use sh instead of whatever shell you yourself are actively using at the time of script execution.

So, I don't think it's helpful to make the change from source to . here.

[gucharbon]

@Shackelford-Arden
I don't get your comment. Using source command in a script with /usr/bin/env sh sheebang will result in a failure if you're running on Ubuntu Bionic (18.04).

Unless you explicitely start the script with bash <script_name>.

IMO it is clearly a bug to have a script indicating sh in sheebang and still using source later in the script.

[Shackelford-Arden]

My apologies, I managed to test incorrectly when I was looking at this. Guess that's what I get for moving too quickly :) You're correct that source does not work as intended in this script.

[StephenBrown2]

Shouldn't it be /usr/bin/env bash, then?

[gucharbon]

I think we are thinking a lot for a really small issue 😄

@StephenBrown2 I guess there is no right or wrong between using /usr/bin/env bash in sheebang or using . instead of source.

I don't really care, and I don't think people will want to run the scripts in environments without bash installed by default (like alpine linux for example).

But still, I think that between 2 working solutions, the most portable should always be prefered.

[StephenBrown2]

+1 for . then

[tiangolo]

Thanks for the discussion here everyone!

Yeah, agreed that source is a bit more readable, but . should work in more environments and that wins in the end 😄

Thanks for the PR with the fix @gucharbon ! 🚀

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