Process State Codes
Here are the different values that the S, stat and state output specifiers (Header "stat" or "S") will display to describe the state of a process.
D uninterruptible sleep (usually Io)
R running or runnable (on run Queue)
S interruptible sleep (waiting for an event to complete)
T stopped, either by a job control signal or because it is being traced.
W paging (not valid since the 2.6.xx kernel)
X dead (shocould never be seen)
Z defunct ("zombie") process, terminated but not reaped by its parent.
For BSD formats and when the stat keyword is used, additional characters may be displayed:
<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