LINFO > man

PS

Section: Linux User's Manual (1)
Updated: March 11, 1999
Index

NAME

ps - report process status

SYNOPSIS

ps [options]

DESCRIPTION

ps gives a snapshot of the current processes. If you want a repetitive update of this status, use top. This man page documents the /proc-based version of ps, or tries to.

COMMAND-LINE OPTIONS

This version of ps accepts several kinds of options.

: Unix98 options may be grouped and must be preceeded by a dash.
BSD options may be grouped and must not be used with a dash.
GNU long options are preceeded by two dashes.

Options of different types may be freely mixed.

Set the I_WANT_A_BROKEN_PS environment variable to force BSD syntax even when options are preceeded by a dash. The PS_PERSONALITY environment variable (described below) provides more detailed control of ps behavior.

SIMPLE PROCESS SELECTION

Switch	Description
-A	select all processes
-N	negate selection
-a	select all with a tty except session leaders
-d	select all, but omit session leaders
-e	select all processes
T	select all processes on this terminal
a	select all processes on a terminal, including those of other users
g	really all, even group leaders (does nothing w/o SunOS settings)
r	restrict output to running processes
x	select processes without controlling ttys
--deselect	negate selection

PROCESS SELECTION BY LIST

Switch	Description
-C	select by command name
-G	select by RGID (supports names)
-U	select by RUID (supports names)
-g	select by session leader OR by group name
-p	select by PID
-s	select processes belonging to the sessions given
-t	select by tty
-u	select by effective user ID (supports names)
U	select processes for specified users
p	select by process ID
t	select by tty
--Group	select by real group name or ID
--User	select by real user name or ID
--group	select by effective group name or ID
--pid	select by process ID
--sid	select by session ID
--tty	select by terminal
--user	select by effective user name or ID
-123	implied --sid
123	implied --pid

OUTPUT FORMAT CONTROL

Switch	Description
-O	is preloaded "-o"
-c	different scheduler info for -l option
-f	does full listing
-j	jobs format
-l	long format
-o	user-defined format
-y	do not show flags; show rss in place of addr
O	is preloaded "o" (overloaded)
X	old Linux i386 register format
j	job control format
l	display long format
o	specify user-defined format
s	display signal format
u	display user-oriented format
v	display virtual memory format
--format	user-defined format

OUTPUT MODIFIERS

Switch	Description
-H	show process hierarchy (forest)
-m	show all threads
-n	set namelist file
-w	wide output
C	use raw CPU time for %CPU instead of decaying average
N	specify namelist file
O	sorting order (overloaded)
S	include some dead child process data (as a sum with the parent)
c	true command name
e	show environment after the command
f	ASCII-art process hierarchy (forest)
h	do not print header lines (repeat header lines in BSD personality)
m	all threads
n	numeric output for WCHAN and USER
w	wide output
--cols	set screen width
--columns	set screen width
--cumulative	include some dead child process data (as a sum with the parent)
--forest	ASCII art process tree
--html	HTML escaped output
--headers	repeat header lines
--no-headers	print no header line at all
--lines	set screen height
--nul	unjustified output with NULs
--null	unjustified output with NULs
--rows	set screen height
--sort	specify sorting order
--width	set screen width
--zero	unjustified output with NULs

INFORMATION

Switch	Description
-V	print version
L	list all format specifiers
V	show version info
--help	print help message
--info	print debugging info
--version	print version

OBSOLETE

Switch	Description
A	increase the argument space (DecUnix)
M	use alternate core (try -n or N instead)
W	get swap info from ... not /dev/drum (try -n or N instead)
k	use /vmcore as c-dumpfile (try -n or N instead)

NOTES

The "-g" option can select by session leader OR by group name. Selection by session leader is specified by many standards, but selection by group is the logical behavior that several other operating systems use. This ps will select by session leader when the list is completely numeric (as sessions are). Group ID numbers will work only when some group names are also specified.

The "m" option should not be used. Use "-m" or "-o" with a list. ("m" displays memory info, shows threads, or sorts by memory use)

The "h" option is problematic. Standard BSD ps uses the option to print a header on each page of output, but older Linux ps uses the option to totally disable the header. This version of ps follows the Linux usage of not printing the header unless the BSD personality has been selected, in which case it prints a header on each page of output. Regardless of the current personality, you can use the long options --headers and --no-headers to enable printing headers each page and disable headers entirely, respectively.

Terminals (ttys, or screens of text output) can be specified in several forms: /dev/ttyS1, ttyS1, S1. Obsolete "ps t" (your own terminal) and "ps t?" (processes without a terminal) syntax is supported, but modern options ("T", "-t" with list, "x", "t" with list) should be used instead.

The BSD "O" option can act like "-O" (user-defined output format with some common fields predefined) or can be used to specify sort order. Heuristics are used to determine the behavior of this option. To ensure that the desired behavior is obtained, specify the other option (sorting or formatting) in some other way.

For sorting, BSD "O" option syntax is O[+|-]k1[,[+|-]k2[,...]] Order the process listing according to the multilevel sort specified by the sequence of short keys from SORT KEYS, k1, k2, ... The `+' is quite optional, merely re-iterating the default direction on a key. `-' reverses direction only on the key it precedes. The O option must be the last option in a single command argument, but specifications in successive arguments are catenated.

GNU sorting syntax is --sortX[+|-]key[,[+|-]key[,...]] Choose a multi-letter key from the SORT KEYS section. X may be any convenient separator character. To be GNU-ish use `='. The `+' is really optional since default direction is increasing numerical or lexicographic order. For example, ps jax --sort=uid,-ppid,+pid

This ps works by reading the virtual files in /proc. This ps does not need to be suid kmem or have any privileges to run. Do not give this ps any special permissions.

This ps needs access to a namelist file for proper WCHAN display. The namelist file must match the current Linux kernel exactly for correct output.

To produce the WCHAN field, ps needs to read the System.map file created when the kernel is compiled. The search path is:

: $PS_SYSTEM_MAP
/boot/System.map-`uname -r`
/boot/System.map
/lib/modules/`uname -r`/System.map
/usr/src/linux/System.map
/System.map

The member used_math of task_struct is not shown, since crt0.s checks to see if math is present. This causes the math flag to be set for all processes, and so it is worthless. (Somebody fix libc or the kernel please.)

Programs swapped out to disk will be shown without command line arguments, and unless the c option is given, in brackets.

%CPU shows the cputime/realtime percentage. It will not add up to 100% unless you are lucky. It is time used divided by the time the process has been running.

The SIZE and RSS fields don't count the page tables and the task_struct of a proc; this is at least 12k of memory that is always resident. SIZE is the virtual size of the proc (code+data+stack).

Processes marked <defunct> are dead processes (so-called "zombies") that remain because their parent has not destroyed them properly. These processes will be destroyed by init(8) if the parent process exits.

PROCESS FLAGS

FORKNOEXEC	1	forked but didn't exec
SUPERPRIV	2	used super-user privileges
DUMPCORE	4	dumped core

PROCESS STATE CODES

D	uninterruptible sleep (usually IO)
R	runnable (on run queue)
S	sleeping
T	traced or stopped
Z	a defunct ("zombie") process

For BSD formats and when the "stat" keyword is used, additional letters may be displayed:

W	has no resident pages
<	high-priority process
N	low-priority task
L	has pages locked into memory (for real-time and custom IO)

SORT KEYS

Note that the values used in sorting are the internal values ps uses and not the `cooked' values used in some of the output format fields. Pipe ps output into the sort(1) command if you want to sort the cooked values.

KEY	LONG	DESCRIPTION
c	cmd	simple name of executable
C	cmdline	full command line
f	flags	flags as in long format F field
g	pgrp	process group ID
G	tpgid	controlling tty process group ID
j	cutime	cumulative user time
J	cstime	cumulative system time
k	utime	user time
K	stime	system time
m	min_flt	number of minor page faults
M	maj_flt	number of major page faults
n	cmin_flt	cumulative minor page faults
N	cmaj_flt	cumulative major page faults
o	session	session ID
p	pid	process ID
P	ppid	parent process ID
r	rss	resident set size
R	resident	resident pages
s	size	memory size in kilobytes
S	share	amount of shared pages
t	tty	the minor device number of tty
T	start_time	time process was started
U	uid	user ID number
u	user	user name
v	vsize	total VM size in bytes
y	priority	kernel scheduling priority

AIX FORMAT DESCRIPTORS

This ps supports AIX format descriptors, which work somewhat like the formatting codes of printf(1) and printf(3). For example, the normal default output can be produced with this: ps -eo "%p %y %x %c"

CODE	NORMAL	HEADER
%C	pcpu	%CPU
%G	group	GROUP
%P	ppid	PPID
%U	user	USER
%a	args	COMMAND
%c	comm	COMMAND
%g	rgroup	RGROUP
%n	nice	NI
%p	pid	PID
%r	pgid	PGID
%t	etime	ELAPSED
%u	ruser	RUSER
%x	time	TIME
%y	tty	TTY
%z	vsz	VSZ

STANDARD FORMAT SPECIFIERS

These may be used to control both output format and sorting.
For example: ps -eo pid,user,args --sort user

CODE	HEADER
%cpu	%CPU
%mem	%MEM
alarm	ALARM
args	COMMAND
blocked	BLOCKED
bsdstart	START
bsdtime	TIME
c	C
caught	CAUGHT
cp	CP
cpu	CPU
cmd	CMD
comm	COMMAND
command	COMMAND
cputime	TIME
drs	DRS
dsiz	DSIZ
egid	EGID
egroup	EGROUP
eip	EIP
esp	ESP
etime	ELAPSED
euid	EUID
euser	EUSER
f	F
fgid	FGID
fgroup	FGROUP
flag	F
flags	F
fname	COMMAND
fsgid	FSGID
fsgroup	FSGROUP
fsuid	FSUID
fsuser	FSUSER
fuid	FUID
fuser	FUSER
gid	GID
group	GROUP
ignored	IGNORED
intpri	PRI
lim	LIM
longtname	TTY
lstart	STARTED
m_drs	DRS
m_trs	TRS
maj_flt	MAJFL
majflt	MAJFLT
min_flt	MINFL
minflt	MINFLT
ni	NI
nice	NI
nwchan	WCHAN
opri	PRI
pagein	PAGEIN
pcpu	%CPU
pending	PENDING
pgid	PGID
pgrp	PGRP
pid	PID
pmem	%MEM
policy	POL
ppid	PPID
pri	PRI
rgid	RGID
rgroup	RGROUP
rss	RSS
rssize	RSS
rsz	RSZ
rtprio	RTPRIO
ruid	RUID
ruser	RUSER
s	S
sess	SESS
session	SESS
sgi_p	P
sgi_rss	RSS
sgid	SGID
sgroup	SGROUP
sid	SID
sig	PENDING
sig_block	BLOCKED
sig_catch	CATCHED
sig_ignore	IGNORED
sig_pend	SIGNAL
sigcatch	CAUGHT
sigignore	IGNORED
sigmask	BLOCKED
stackp	STACKP
start	STARTED
start_stack	STACKP
start_time	START
stat	STAT
state	S
stime	STIME
suid	SUID
suser	SUSER
svgid	SVGID
svgroup	SVGROUP
svuid	SVUID
svuser	SVUSER
sz	SZ
time	TIME
timeout	TMOUT
tmout	TMOUT
tname	TTY
tpgid	TPGID
trs	TRS
trss	TRSS
tsiz	TSIZ
tt	TT
tty	TT
tty4	TTY
tty8	TTY
ucomm	COMMAND
uid	UID
uid_hack	UID
uname	USER
user	USER
vsize	VSZ
vsz	VSZ
wchan	WCHAN

ENVIRONMENT VARIABLES

The following environment variables could affect ps:

COLUMNS	Override default display width
LINES	Override default display height
PS_PERSONALITY	Set to one of posix,old,linux,bsd,sun,digital
CMD_ENV	Set to one of posix,old,linux,bsd,sun,digital
I_WANT_A_BROKEN_PS	Force obsolete command line interpretation
LC_TIME	Date format
PS_FORMAT	Default output format override
PS_SYSMAP	Default namelist (System.map) location
PS_SYSTEM_MAP	Default namelist (System.map) location
POSIXLY_CORRECT	Don't find excuses to ignore bad "features"
UNIX95	Don't find excuses to ignore bad "features"
_XPG	Cancel CMD_ENV=irix non-standard behavior

In general, it is a bad idea to set these variables. The two exceptions are CMD_ENV (or PS_PERSONALITY), to set the desired default personality, and POSIXLY_CORRECT (or UNIX95), which should be set for Unix98 standard compliance.

PS_PERSONALITY	Description
none	"Do the right thing"
aix	like AIX ps
bsd	like FreeBSD ps
compaq	like Digital Unix ps
debian	like the old Debian ps
digital	like Digital Unix ps
gnu	like the old Debian ps
hp	like HP-UX ps
hpux	like HP-UX ps
irix	like Irix ps
linux	deviate from Unix98 for convenience only
old	like the original Linux ps
posix	standard
sco	like SCO ps
sgi	like Irix ps
sun	like SunOS 4 ps
sunos	like SunOS 4 ps
sysv	standard
unix	standard
unix95	standard
unix98	standard

EXAMPLES

To see every process on the system using standard syntax:

: ps -e

To see every process on the system using BSD syntax:

: ps ax

To see every process except those running as root (real & effective ID)

: ps -U root -u root -N

To see every process with a user-defined format:

: ps -eo pid,tt,user,fname,tmout,f,wchan

Odd display with AIX field descriptors:

: ps -o "%u : %U : %p : %a"

Print only the process IDs of syslogd:

: ps -C syslogd -o pid=

STANDARDS

This ps can be set to conform to version 2 of the Single Unix Specification.

AUTHOR

ps was originally written by Branko Lankester <lankeste@fwi.uva.nl>.
Michael K. Johnson <johnsonm@redhat.com> re-wrote it significantly to use the proc filesystem, changing a few things in the process.
Michael Shields <shields@msrl.com> added the pid-list feature.
Charles Blake <cblake@bbn.com> added multi-level sorting, the dirent-style library, the device name-to-number mmaped database, the approximate binary search directly on System.map, and many code and documentation cleanups.
David Mosberger-Tang wrote the generic BFD support for psupdate.
Albert Cahalan <acahalan@cs.uml.edu> rewrote ps for full Unix98 and BSD support, along with some ugly hacks for obsolete and foreign syntax.

Michael K. Johnson <johnsonm@redhat.com> is the current maintainer.

Please send bug reports to <procps-list@redhat.com>

Index

NAME

SYNOPSIS

DESCRIPTION

COMMAND-LINE OPTIONS

SIMPLE PROCESS SELECTION
PROCESS SELECTION BY LIST
OUTPUT FORMAT CONTROL
OUTPUT MODIFIERS
INFORMATION
OBSOLETE

NOTES

PROCESS FLAGS
PROCESS STATE CODES
SORT KEYS
AIX FORMAT DESCRIPTORS
STANDARD FORMAT SPECIFIERS
ENVIRONMENT VARIABLES

Created from the Linux Online Manual Pages
August 23, 2005 by The Linux Information Project