GCC -lm -lz -lrt options - what are they about?

Question

I know, that these are some common/basic libraries, but what do they mean exactly?

For example, I know, that -lm is some math library, but is this the st

Answer 1

• -lz - is zlib, http://zlib.net/
• -lm - is the math library as you've worked out (implementation defined AFAIK)
• -lrt- provides POSIX realtime extensions: http://www.s-gms.ms.edus.si/cgi-bin/man-cgi?librt+3LIB