What is the usage of -fs in brew install example -fs and what is bottle block?

Because I want to install mcrypt, I use brew install php56-mcrypt, but after the installation, I check that mcrypt is not loaded in phpinfo(). I persist and find:

The installed php has debug mode turned on, but mcrypt does not. I found an issue on github:
https://github.com/Homebrew/h...
It can be solved by using brew install php56-mcrypt -fs , it can indeed be solved by actual operation,

The explanation in the

issue isJust pass -fs to your install arguments. brew install example -fs. It'll skip the bottle block entirely.
But I didn't figure it out. Adding the -fs parameter means skipping the bottle block｀ ? What is ｀bottle block`?

Reply content:

Because I want to install mcrypt, I use brew install php56-mcrypt, but after the installation, I check that mcrypt is not loaded in phpinfo(). I persist and find:

The installed php has debug mode turned on, but mcrypt does not. I found an issue on github:
https://github.com/Homebrew/h...
Use brew install php56-mcrypt -fs to solve it , it can indeed be solved by actual operation,

The explanation in the

issue isJust pass -fs to your install arguments. brew install example -fs. It'll skip the bottle block entirely.
But I didn't figure it out. Adding the -fs parameter means skipping the bottle block｀ ? What is ｀bottle block`?

bottle block refers to the bottle code block, which is the code used by brew to directly download the binary package for installation. Adding -fs means --build-from-source, which means compiling and installing from source code