Linux Process Status Codes

In a Linux System, every process has a status expressed with the 'STAT' column in output of the 'ps' command. 'ps' command displays an uppercase letter for the process state.

Here are the different values for the output specifiers:

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 (should never be seen)

Z    defunct ("zombie") process, terminated but not reaped by its parent

for illustration, an example output of a 'ps' command:

$ ps -eo state,pid,user,cmd
S   1            root           /sbin/init
S   5274      root           smbd -F
D   4668     postgres     postgres: wal writer process
S   7282      root           nmbd -D
S   7349      root           /usr/sbin/winbindd -F
R   11676   postfix       cleanup -z -t unix -u
S   25354   _graphi+    (wsgi:_graphite)  -k start