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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 con-
tains 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
S The state of the process. 0: nonexistent; S: sleeping; W: waiting; 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 possible 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 address.
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
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 somewhat 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 second argument is given, it is taken to be
the file containing the system's namelist.
/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
Some data printed for defunct processes is irrelevant
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