About the UNIX system

UNIX system knowledge

• I/O (Input/Output, IMPORTANT): what is stdin, stdout, stderr. What does "|" (pipe) do.

• Job control (IMPORTANT): top, kill, jobs, bg, fg, use "&" to put job in bg, nohup

• What is process, what is thread?

• What is local variable, especially, what is the (most useful) PATH variable and how to change the PATH variable in ~/.bashrc.

• Basic navigation: pwd, cd, ls (ls -l, ls -hl, ls -hal, understand output of ls -l)

• Read files: cat, less, file(tell you whether a file is binary or is compressed), head, tail, grep, sort

• Manipulate files:cp, mv, rm, mkdir, ln -s

• Working with commands: type, which, help, man

• Permissions: chmod

For quick introduction, I really recommend this short book. The "Learning the Shell" chapter is about all the must-know of using UNIX systems (Linux, Mac OS), fairly enough for a beginning. The above list is actually based on this chapter.