From "man ps":

R = Running or Runnable
S = interruptable Sleep
T = sTopped
Z = Zombie

D = uninterruptible sleep (usually IO)

Where does this D come from?

  • 1
    "D"ormant comes to mind
    – MelBurslan
    Mar 3, 2016 at 20:51
  • 3
    _D_isk, I believe
    – Jeff Schaller
    Mar 3, 2016 at 20:56
  • 1
    @JeffSchaller with all due respect, not all I/O is "disk" bound.
    – MelBurslan
    Mar 3, 2016 at 20:59
  • @Mel - granted; Disk is just my mnemonic for it. This Q might benefit from a 'history' tag, as it may have just been down to the most reasonable remaining choice by the 'ps' programmer.
    – Jeff Schaller
    Mar 3, 2016 at 21:40
  • 2
    @MelBurslan Nonetheless, that's where it comes from. (“Device” would be more technically accurate but not historically correct). Mar 3, 2016 at 23:44

1 Answer 1


From the 4BSD ps man page:

The state is given by a sequence of four letters, e.g. ``RWNA''. The first letter indicates the runnability of the process: R for runnable processes, T for stopped processes, P for processes in page wait, D for those in disk (or other short term) waits, S for those sleeping for less than about 20 seconds, and I for idle (sleeping longer than about 20 seconds) processes.

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