Most of the GNU compilers (those based on the GCC backend) have been installed, these include the following languages:

• C, command line tool is: gcc.
• C++, command line tool is: g++.
• Java, command line tool is: gcj.
• Modula-2, command line tool is: gm2.
• Pascal, command line tool is: gpc.

These compilers all use exactly the same code generator and thus aside from language overheads they will produce similar output code for semantically equivalent source input. Or put another way, C, Pascal and Modula-2 should be nearly identically efficient. Whereas Java and C++ will probably be likewise runtime inefficient due to language design.

A great advantage of using the GNU family of compilers is that they share many similar options. For example to generate debugging information on any one of these compilers add the command line option, -g. Below is a cheat sheet of useful options:

• -g turns on debugging information, it does not slow the executable down.
• -c do not attempt to link the object file.
• -Os optimise for space.
• -O0 no optimisation.
• -O default optimisation.
• -O3 highest optimisation, inlines functions, unrolls loops etc.

When developing code it would be wise to use -O0 -g to preserve the relationship between source code and executable.

Finally you can debug your programs with the graphical ddd or if you prefer, from the command line via: gdb. The debugger supports all the languages.