The juice of this blog post is here: AT&T x86 assembly instruction reference can be found in the Appendix B. with the the title “Common x86 Instructions” from Programming from the Ground Up by Bartlett, J.
The actual process how I came about finding this bit of info was when I was reading Building Secure Software by Viega, J and McGraw, G in towards efforts of finishing my bachelor and master thesis on “Common faults in software which lead to a vulnerability”. The book is a brilliant as an entry level book for everyone working on software development and trying to think more securely when programming. Although hopefully my master’s thesis will serve this entry level of thinking secure while programming as well. Anyway, I was reading the BSS book and on the Stack Overflows chapter there’s this part where you’re told to use the gcc with -S flag to compile the C code to Assembly language and tweak it. So to be able to tweak it I wanted to understand what were the instructions in the Assembly language. I googled a bit to find AT&T instructions and that didn’t give me much until I finally found a question on comp.lang.asm.x86 news group which said that one would be in the Programming from the Ground Up book and there it was.