-fsyntax-only is to check the code for syntax errors, and don't do anything beyond that.
-xc is to specify C language. Other interesting option for example
c++. This flag is mandatory when reading from
- is to read text from
<<< is to redirect text to
stdin of a command, also known as a here string. You can read more about this in
man bash in the
Here Strings section.
Note that "text snippet" must be enclosed within double-quotes, otherwise only the first word will be part of the here string, the rest will be interpreted as additional command line arguments to the