D    不可中断睡眠 (通常是在IO操作)
R    正在运行或可运行（在运行队列排队中）
S    可中断睡眠 (在等待某事件完成)
T    Stopped, either by a job control signal or because it is being traced.
W    正在换页(2.6.内核之前有效)
X    死进程 (should never be seen)
Z    僵尸

BSD风格的
<    high-priority (not nice to other users)
N    low-priority (nice to other users)
L    has pages locked into memory (for real-time and custom IO)
s    is a session leader
l    is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+    is in the foreground process group