conditional binary operator expected

[vladkras]

I catch this error conditional binary operator expected on every line with

if [[ -v "VARNAME" ]] ...

consider using

if [[ ${VARNAME} ]] ...

instead. It seems -v was introduced in bash 4+ while macos still uses version 3

[byrnedo]

ok, will fix
The reason I did this was due to having set -u.

[vladkras]

@byrnedo, I replaced -v with ${...} and checked on bash v.3 to 5 (see #12)

Also I added Travis CI testing but I can exclude them from pull request #12 if you don't need'em at all