PS linux command manual
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.
Unix 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
-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
-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
--ppid select by parent 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"
-F extra full format
-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
-Z display security context format (NSA SELinux, etc.)
--format user-defined format
--context display security context format (NSA SELinux, etc.)
-H show process hierarchy (forest)
-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 no header (or, one header per screen in the BSD personality)
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
--headers repeat header lines, one per page of output
--no-headers print no header line at all
--lines set screen height
--rows set screen height
--sort specify sorting order
--width set screen width
-L show threads, possibly with LWP and NLWP columns
-T show threads, possibly with SPID column
-m show threads after processes
H show threads as if they were processes
m show threads after processes
-V print version
L list all format specifiers
V show version info
--help print help message
--info print debugging info
--version print version
A increases 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)
User-defined format options ("o", "-o", "O", and "-O") offer
a way to specify individual output columns. Headers may be
renamed ("ps -o pid,ruser=RealUser -o comm=Command") as desired.
If all column headers are empty ("ps -o pid= -o comm=") then the
header line will not be output. Column width will increase as
needed for wide headers; this may be used to widen up columns
such as WCHAN ("ps -o pid,wchan=WIDE-WCHAN-COLUMN -o comm").
Explicit width control ("ps opid,wchan:42,cmd") is offered too.
The behavior of "ps -o pid=X,comm=Y" varies with personality;
output may be one column named "X,comm=Y" or two columns
named "X" and "Y". Use multiple -o options when in doubt.
Use the $PS_FORMAT environment variable to specify a default
as desired; DefSysV and DefBSD are macros that may be used to
choose the default UNIX or BSD columns.
The following user-defined format specifiers may contain
spaces: comm, args, cmd, comm, command, fname, ucmd, ucomm,
lstart, bsdstart, start
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 for 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, obsolete 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
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
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
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 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 4 used super-user privileges
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 kB
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_COLORS Not currently supported.
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 one exception
is CMD_ENV or PS_PERSONALITY, which could be set to Linux for normal
systems. Without that setting, ps follows the useless and bad parts
of the Unix98 standard.
390 like the S/390 OpenEdition ps
aix like AIX ps
bsd like FreeBSD ps (totally non-standard)
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 ***** RECOMMENDED *****
old like the original Linux ps (totally non-standard)
sco like SCO ps
sgi like Irix ps
sun like SunOS 4 ps (totally non-standard)
sunos like SunOS 4 ps (totally non-standard)
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) pgrep(1) pstree(1) proc(5)
This ps conforms to version 2 of the Single Unix Specification.
ps was originally written by Branko Lankester . Michael
K. Johnson re-wrote it significantly to use the proc
filesystem, changing a few things in the process. Michael Shields
added the pid-list feature. Charles Blake
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
Mossberger-Tang wrote the generic BFD support for psupdate. Albert Cahalan
rewrote ps for full Unix98 and BSD support, along with
some ugly hacks for obsolete and foreign syntax.
Please send bug reports to
Linux July 5, 1998 PS(1)