PS(1) General Commands Manual PS(1)
ps - process status
ps [ aklx ] [ namelist ]
Ps prints certain indicia about active processes. The a option asks
for information about all processes with terminals (ordinarily only
one's own processes are displayed); x asks even about processes with no
terminal; l asks for a long listing. The short listing contains the
process ID, tty letter, the cumulative execution time of the process
and an approximation to the command line.
The long listing is columnar and contains
F Flags associated with the process. 01: in core; 02: system
process; 04: locked in core (e.g. for physical I/O); 10: being
swapped; 20: being traced by another process.
S The state of the process. 0: nonexistent; S: sleeping; W: wait-
ing; R: running; I: intermediate; Z: terminated; T: stopped.
UID The user ID of the process owner.
PID The process ID of the process; as in certain cults it is possi-
ble to kill a process if you know its true name.
PPID The process ID of the parent process.
CPU Processor utilization for scheduling.
PRI The priority of the process; high numbers mean low priority.
NICE Used in priority computation.
ADDR The core address of the process if resident, otherwise the disk
SZ The size in blocks of the core image of the process.
WCHAN The event for which the process is waiting or sleeping; if
blank, the process is running.
TTY The controlling tty for the process.
TIME The cumulative execution time for the process.
The command and its arguments.
A process that has exited and has a parent, but has not yet been waited
for by the parent is marked <defunct>. Ps makes an educated guess as
to the file name and arguments given when the process was created by
examining core memory or the swap area. The method is inherently some-
what unreliable and in any event a process is entitled to destroy this
information, so the names cannot be counted on too much.
If the k option is specified, the file /usr/sys/core is used in place
of /dev/mem. This is used for postmortem system debugging. If a sec-
ond argument is given, it is taken to be the file containing the sys-
/unix system namelist
/dev/mem core memory
/usr/sys/core alternate core file
/dev searched to find swap device and tty names
Things can change while ps is running; the picture it gives is only a
close approximation to reality.
Some data printed for defunct processes is irrelevant