An in depth look at the compiler

Note: If you are new to Crystal and/or programming, I recommend reading and understanding the basics first, before digging in to the details on this page.

Creating a dynamically-linked executable

The build command is used to create an executable file.

$ crystal build hello_world.cr

Which can then be run with the following command:

$ ./hello_world

These executables are not fully optimized however. To optimize them, use the --release flag. This flag should always be used for production ready executables and when performing benchmarks. To decrease the binary size the --no-debug along with the strip command can be used.

Creating a statically-linked executable (standalone)

Simply add the --static flag to the command.

$ crystal build hello_world.cr --release --static

And run it like a dynamically-linked executable.

$ ./hello_world

Disclaimer! To create a standalone executable, all required libraries MUST be installed. A list of these libraries can be found here. For all available commands, simply run crystal without any commands or flags in your terminal. For a list of options available on each command, add the --help flag after the command, e.g. crystal build --help. The Crystal compiler supports the following input format: crystal build [options] [programfile] [--] [arguments]