Cannot find pkg-config error

For Ubuntu/Debian OS,

apt-get install -y pkg-config

For Redhat/Yum OS,

yum install -y pkgconfig

For Archlinux OS,

pacman -S pkgconf

Answer to my question (after several Google searches) revealed the following:

$ curl https://pkgconfig.freedesktop.org/releases/pkg-config-0.29.tar.gz -o pkgconfig.tgz
$ tar -zxf pkgconfig.tgz && cd pkg-config-0.29
$ ./configure && make install

from the following link: Link showing above

Thanks to everyone for their comments, and sorry for my linux/OSX ignorance!

Doing this fixed my issues as mentioned above.

for me, (OSX) the problem was solved doing this:

brew install pkg-config