What does the "sdl-config" mean when compiling sdl c program? - c++

Question

In many tutorials I saw sdl-config for compile a sdl c program. In c++ examples I have seen too.
Here is an example from here.
g++ sdlExample.cpp `sdl-config --cflags --libs` -o sdlExample
What does the sdl-config --cflags --libs mean ? Why inside accent ?

Answer 1

In a shell, where your command is executed, the reverse quotes imply command substitution. So, basically, whatever is within reverse quotes is executed as a command, and its output is substituted.
Example:
echo Today is `date`
Will first execute the date command, and substitute it's output.
echo Today is Sat Dec 19 14:32:13 EST 2015
Which is then executed to produce:
Today is Sat Dec 19 14:32:13 EST 2015
So, in your command,
g++ sdlExample.cpp `sdl-config --cflags --libs` -o sdlExample
The shell will first execute,
sdl-config --cflags --libs
And substitute its output,
g++ sdlExample.cpp <output of the above command> -o sdlExample
And then finally execute the resulting command line.
To see what is actually executed after command substitution, just add echo in the front.
echo g++ sdlExample.cpp `sdl-config --cflags --libs` -o sdlExample
This will show you the resulting command line.
Note that there is an alternative syntax for command substitution as well, which is preferred when you have complex, nested substitutions.
echo g++ sdlExample.cpp $(sdl-config --cflags --libs) -o sdlExample
This is a pretty standard technique to generate proper command line options for a library / framework, where the options depend on installation etc. In this case, the sdl-config command generates the necessary compiler options (cflags and libs) for the sdl package. You can experiment with what else it can do by executing it directly on the command line.
sdl-config --cflags --libs
sdl-config man page

Answer 2

It just outputs appropriate flags to pass on to the compiler, similar to what pkg-config does with its .pc files (located in /usr/lib/pkgconfig).