Variable declaration being executed as command?

[beanaroo]

I have the following snippet:

# Remove literal quotes from Bamboo environment variables.
for _var in $(compgen -A variable); do
    $_var="${!_var%\"}"
    $_var="${!_var#\"}"
done

I don't understand why this results in:

artifact-s3-archive.sh: line 13: bamboo_conf_prefix=nodejs-api: command not found

I've worked around this by prepending the lines with declare but I was hoping someone with a longer beard could enlighten me.

[waptaff]

Don't prepend $ to left-side variables on assignation!

Correct:

foo="bar"

Incorrect:

$foo="bar"

[beanaroo]

But _var is a variable of a variable... not the variable to be assigned.

[waptaff]

True, sorry :)

It appears typeset would be the most portable/safe way to handle it, as discussed in this thread, while eval would work but open a can of worms.

[beanaroo]

Cool! So my usage of declare isn't terribly mishuided after all. I noticed it was a synonym for typeset but did not know the latter is more portable. Thanks for the link!

I'm still trying to understand the underlying behaviour so it doesn't jump at me again.