Proper fix for dirname in env.sh

[hohwille]

User @maihacke changed env.sh to use $(dirname "$0"):
b9cca78#diff-59bbdf4f0007715da1871587ba4ffd3d

I assume this was some kind of bugfix for MacOS. Also this seems more reliable to me as $BASH_SOURCE is proprietary and only works in bash. What is the purpose why this was ever changed to this?

User @vapadwal wants to change env.sh back to $(dirname "$BASH_SOURCE"):
985a51e#diff-59bbdf4f0007715da1871587ba4ffd3d

As I do not like to have git wars, I would kindly ask all participants to clarify the reasons for these changes and find a peaceful solution.

[hohwille]

I was able to reproduce the error somehow:

Jorgs-MacBook-Pro:devon hohwille$ . env.sh
dirname: illegal option -- b
usage: dirname path
IDE environment has been initialized.
Jorgs-MacBook-Pro:devon hohwille$ echo $0
-bash

So in some cases bash has -bash as $0 what is causing the issue (then dirname is -).
Hence I think both "fixes" are wrong.
IMHO we need an if that tests if we are in bash and then uses $BASH_SOURCE and otherwise uses $0 to make it work in any shell.

[hohwille]

So IMHO $BASH_SOURCE refers to the file that has been sourced (via . script or source script) whereas $0 refers to the invocation of a script (will be path/script or script depending on how you called the script). Hence $0 never makes sense for env.sh. The question is more how can we make env.sh work with other shells such as zsh?

[maihacke]

Maybe this could be a solution (please try an report, if it works):

#!/bin/bash
#
# Source this script from a BASH shell to setup the shell for the corresponding project.
# 
pushd "$(dirname "${BASH_SOURCE:-$_}")" >/dev/null
export OASP_PROJECT_HOME=`pwd`

. $PWD/scripts/environment-project

popd > /dev/null

[hohwille]

Create test.sh with this content:

echo "0=$0"
echo "BASH_SOURCE=$BASH_SOURCE"
echo "_=$_"

This will produce:

$ . ./test.sh
0=-bash
BASH_SOURCE=./test.sh
_=BASH_SOURCE=./test.sh

I hope this makes it clear. $0 was always wrong, had been fixed and was accidentally be reintroduced via PR (I assume some copy & paste from old source).
$BASH_SOURCE is correct but will only work in bash.

[hohwille]

$ zsh
% . ./test.sh
0=./test.sh
BASH_SOURCE=
_=BASH_SOURCE=

So in zsh the $0 variant is correct.

[hohwille]

$_ seems to be the last command (even within the current script)

[maihacke]

yepp, nonsense :-/

[maihacke]

maybe we should go with ${BASH_SOURCE[0]-$0} then
Should work in Bash and ZSH

➜  ~ cat test.sh 
echo "0=$0"
echo "BASH_SOURCE=$BASH_SOURCE"
echo "_=$_"
echo "${BASH_SOURCE[0]-$0}"

➜  ~ . ./test.sh 
0=./test.sh
BASH_SOURCE=
_=BASH_SOURCE=
./test.sh

➜  ~ bash
bash-3.2$ . ./test.sh 
0=bash
BASH_SOURCE=./test.sh
_=BASH_SOURCE=./test.sh
./test.sh

[hohwille]

We only need to review and merge PR #25 that fixes this issue together with #21.

[hohwille]

fixed with PR #21