bash: cannot find track subdirectory

[glennj]

In bash, when sourcing a file, $0 is not the path of the file being sourced: that is the first element of the BASH_SOURCE array.

If I add a debugging line into xr.sh:

_dir="$(dirname "$(readlink -f "$0")")"
printf ">>%s\n" "$0" "$_dir" "${BASH_SOURCE[0]}"

Then:

$ cd
$ . ~/src/exercism/PaulDance/xr/xr.sh
>>bash
>>/Users/glennjackman
>>/Users/glennjackman/src/exercism/PaulDance/xr/xr.sh

[glennj]

Perhaps something gross like

if [[ -n $ZSH_VERSION ]]; then
    _dir="$(dirname "$(readlink -f "$0")")"
elif [[ -n $BASH_VERSION ]]; then
    _dir="$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")"
fi

or

if [[ -n $BASH_VERSION ]]; then
    _script=${BASH_SOURCE[0]}
else
    _script=$0
fi
_dir="$(dirname "$(readlink -f "${_script}")")"
unset _script

[PaulDance]

Interesting incompatibility. Is Zsh the only one treating $0 as the sourced file or is Bash the only one using BASH_SOURCE like your second solution suggests?

[glennj]

It seems this is something special that both bash and zsh do.

• zsh documents it in zshparam (http://zsh.sourceforge.net/Doc/Release/Parameters.html#Parameters-Set-By-The-Shell)
• bash does not even seem to document what it does with the BASH_SOURCE array. Grr.
• dash, ksh: I can't see how to get the name of the file currently being sourced.

[PaulDance]

Alright, thanks for the research. Let's adopt the second solution for now, as it fixes the current problem. If someone uses Ksh, then let's wait for them to complain if $0 does not work. I'll try to get more information on my side in the meantime.

[glennj]

Oops, I didn't see your comment before creating the PR.

[PaulDance]

No problem! I was actually peeling and cutting up some vegetables, so I couldn't really do some more research... Fixing this is already great. Further improvements can always wait.