PS(1) Linux User's Manual PS(1)
ps - report process status
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.
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 environ-
ment variable (described below) provides more detailed control of ps behavior.
SIMPLE PROCESS SELECTION
-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
r restrict output to running processes
x select processes without controlling ttys
--deselect negate selection
PROCESS SELECTION BY LIST
-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
-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
-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
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
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
--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
-V print version
L list all format specifiers
V show version info
--help print help message
--info print debugging info
--version print version
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)
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 com-
pletely 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
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 sepa-
rator 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 cor-
To produce the WCHAN field, ps needs to read the System.map file created when the kernel is compiled. The search path is:
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.
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)
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)
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
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 person-
ality, and POSIXLY_CORRECT (or UNIX95), which should be set for Unix98 standard compliance.
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
sco like SCO ps
sgi like Irix ps
sun like SunOS 4 ps
sunos like SunOS 4 ps
To see every process on the system using standard syntax:
To see every process on the system using BSD syntax:
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=
top(1) pstree(1) proc(5)
This ps can be set to conform to version 2 of the Single Unix Specification.
ps was originally written by Branko Lankester <email@example.com>.
Michael K. Johnson <firstname.lastname@example.org> re-wrote it significantly to use the proc filesystem, changing a few things in the process.
Michael Shields <email@example.com> added the pid-list feature.
Charles Blake <firstname.lastname@example.org> added multi-level sorting, the dirent-style library, the device name-to-number mmaped database, the approxi-
mate binary search directly on System.map, and many code and documentation cleanups.
David Mosberger-Tang wrote the generic BFD support for psupdate.
Albert Cahalan <email@example.com> rewrote ps for full Unix98 and BSD support, along with some ugly hacks for obsolete and foreign syn-
Michael K. Johnson <firstname.lastname@example.org> is the current maintainer.
Please send bug reports to <email@example.com>