Use author env variable if set

[keiravillekode]

bin/create-exercise now uses the author environment variable, if set, instead of requesting github handle.

A few other tracks already use this approach.

[glennj]

I don't see how $author is initialized, unless it's an environment variable.

[keiravillekode]

read is a builtin command that sets environment variables.

read -rp "What's your GitHub handle? "

sets REPLY

read -rp "What's your GitHub handle? " author

sets author

https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html#index-read

https://www.computerhope.com/unix/bash/read.htm

[keiravillekode]

Other tracks using this same environment variable:

8th/bin/add-exercise:    read -rp 'Your github username: ' author
arm64-assembly/bin/create-exercise:    read -rp "What's your github username? " author
idris/bin/create-exercise.sh:    read -rp "What's your github username? " author
jq/bin/add-exercise:read -rp 'Your github username: ' author
julia/bin/add-practice-exercise:    read -rp 'Your GitHub username: ' author
mips/bin/create-exercise:    read -rp "What's your github username? " author
r/bin/add-practice-exercise:    read -rp 'Your GitHub username: ' author
roc/bin/add-exercise:    read -rp 'Your github username: ' author
vlang/bin/bootstrap_practice_exercise.sh:    read -rp "What's your github username? " author
x86-64-assembly/bin/create-exercise:    read -rp "What's your github username? " author

[glennj]

Believe me, I'm well aware how read works. I'm talking about line 25: [[ -z $author ]] -- when will the variable ever not be empty at line 25? I'm questioning the purpose of this PR.

BTW read does not set environment variables, it sets a shell variable. It's up to export or declare -x to make it available in the environment. This is a pet peeve of mine.

[keiravillekode]

Sorry, I understand the question better now.

Before many tracks had bin/create-exercise scripts, I write my own for each track I was contributing to, that would copy in track-specific files and update .meta/config.json with my github handle.

Now that many tracks have scripts, I should use those. My concern is that I might mistype my github handle. So I set author in my .profile.

It isn't important, we don't need this PR.

[glennj]

I see. In some of the other "create exercise" scripts I've written, I provided the ability to pass the author name by options: ./bin/create_exercise -a glennj forth. Is that something you'd be interested in? You could write create_exercise -a $author $slug

[keiravillekode]

Yes. That would be excellent.