I have read the readme, and instructions, and have successfully compiled some allegro programs.

But will someone kindly, re describe how to do a command line compilation of a program written with allegro functions, using gcc?
How to include it in Fedora Eclipse ?
I tried to inscude it into fedora, linked the libs, but the -lalleg link is giving an error.
Please re describe the process. And let me know why are those links are used, and what they work for.

IIRC, there is a command that "registers" libraries so that the linker can find them (according to the man page it seems like libraries are cached, likely for speed, and in order to find them the linker requires you to cache them). Until you do this the linker won't find the libraries you have installed since it was last executed. Something like ldconfig or something...

ldconfig

I haven't been using Linux enough recently to be sure, but that sounds right. Always check the man page before executing a command, however. There appears to be a configuration file for ld (the linker) called /etc/ld.so.conf so you might want to check that out as well (to make sure the Allegro libraries are in one of the specified directories).

As Cody Harris said, there is a script in the Linux installation of Allegro that automatically outputs library options. It is called allegro-config. Therefore, you can use either back-tick syntax (`command`) or dollar-sign parenthesis syntax ($(command)) (depending on which shell you're using) to automatically insert the correct library options onto your command-line.

gcc options `allegro-config --libs` source_files
gcc options $(allegro-config --libs) source_files

IIRC, $(command) is the new "right" way, but `command` is compatible with more/older shells.

I use a Speedhack makefile, with a few modifications for profiling and debugging.

Not sure if it adds much but if you want to link against allegro's debug library use:

gcc -W -Wall -ggdb3 -c file.c
gcc file.o -o program `allegro-config --libs debug`