"2. Learning the Vi and Vim Editors, by Arnold Robbins. I'm a command-line junkie. So, naturally I'm a huge fan of Vi and Vim editors. Several years back, when I wrote lot of C code on Linux, I used to carry the Vi editor pocket reference with me all the times. Even if you've been using Vi and Vim Editors for several years and have not read this book, please do yourself a favor and read this book. You'll be amazed with the capabilities of Vim editor.
"3. Bash Cookbook, by Carl Albing, JP Vossen and Cameron Newham. Whether you are a sysadmin, DBA or a developer, you have to write shell script at some point. A wise sysadmin knows that once you've mastered the shell-scripting techniques, you can put your servers on auto-pilot mode by letting the shell-scripts do the grunt work. To get to the auto-pilot mode of sysadmin, you definitely need to master the examples provided in this cookbook. There are quiet few Bash shell books out there. But, this books tops them all by giving lot of detailed examples"
