XEmacs (http://www.xemacs.org) is a highly configurable editor that
does everything (and more) that you ever wanted from a programming
editor. Actually, I posted this newsarticle from the built-in
newsreader. It does require a little learning, though. There is also
FSF Emacs, but it does not come with such a fancy user interface and I
personally believe that XEmacs is easier for beginners (don't flame
me, if you think differently).

For debugging, there is probably no alternative to the GNU debugger
"gdb". But you should consider this program as a back-end, because
directly accessing its text-based interface can be quite
awkward. There are a couple of excellent front-ends. One of them is
built into (X)Emacs, but the best one is IMHO an external program
called DDD http://www.cs.tu-bs.de/softech/ddd/

> 1.  How can I use Assembler under Linux ?

It is possible to use assembly language in Linux, but you usually do
not have to do so. The operating system provides very good abstraction
from the hardware and programming its high-level interface often
results in code that beats hand-coded assembly under DOS. Besides,
Linux programmers usually try to program in a platform-independent
way, so that their code can easily be ported to other environments;
excessive use of assembly language would make this very
difficult. Even the kernel uses comperatively little assembly code and
most of it is portable C code. If you want to know about how to
program in assembly language, then take a look at the "info" pages for
"GCC", "ld", "binutils", ...

> 2.  I'm looking for some good books on the Unix/Linux programming.

There are lots of different books depending on what topic you are most
interested in. If you have never programmed in an POSIX like
environment, then I would strongly suggest that you get hold of
Stevens' "Advanced Programming in the UNIX Environment". This book is
invaluable and it will tell you a lot about the design principles that
guided the development of most UNIX programs! Also, as a general rule,
all books that have been published by O'Reilly http://www.ora.com are
extremely useful. Get hold of a recent catalog and browse the titles.

If you intend to program under X (the GUI environment), then you will
first have to decide which toolkit you want to use. This is a hotly
debated topic that I cannot give a definitive answer for. Most people
seem to aggree, that Qt http://www.troll.no is the most powerful free
toolkit and it is suppossedly very easy to learn; it does require that
you use C++, though. Another nice little toolkit is XForms
http://bragg.phys.uwm.edu/xforms, which is also quite easy to learn,
but not as featureful as Qt. Both of these libraries come with
extensive on-line documentation. They are licensed under different
conditions and this is the main problem, because depending on your
target-group, these licenses might get into the way. A commercial
alternative is Motif, which is more wide-spread on other UNIX
platforms, but which suffers from a cumbersome API; there are
libraries on-top of Motif which improve on this. A particularly
noteworthy example is the Xmt library that comes with O'Reilly's
Volume 6C of the X Windows series. BTW, this series gives a very good
description of X programming and you might want to get some of the
volumes if you are seriously interested in how X works. There are many
other toolkits, but I think these three are the ones that will most
appeal to your needs.

Apart from these resources, you will find that there are tons of very
useful online documents. If you installed Linux from a CD-ROM, then
you probably already have quite a lot of these files in some "docs"
directory (usually on the first CD-ROM of a multi-CD set). You should
also investigate the "man" (or "xman") and the "info" command; you
will need those a lot :-)


Good luck,