PS linux command manual

PS(1)                       Linux User's Manual                        PS(1)

       ps - report process status

ps [options]

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.

-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

-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

-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
correct output.

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

/boot/'uname -r'
/lib/modules/'uname -r'/

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  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


D uninterruptible sleep (usually IO)
R runnable (on run queue)
S sleeping
T traced or stopped
W paging
X dead
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.

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


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"

%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


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

%cpu         %CPU
%mem         %MEM
alarm        ALARM
args         COMMAND
blocked      BLOCKED
bsdstart     START
bsdtime      TIME
c            C
caught       CAUGHT
cmd          CMD
comm         COMMAND
command      COMMAND
context        CONTEXT
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
ppid         PPID
pri          PRI
priority     PRI
rgid         RGID
rgroup       RGROUP
rss          RSS
rssize       RSS
rsz          RSZ
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
ucmd         CMD
ucomm        COMMAND
uid          UID
uid_hack     UID
uname        USER
user         USER
vsize        VSZ
vsz          VSZ
wchan        WCHAN

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 ( location.
    PS_SYSTEM_MAP       Default namelist ( 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)
    posix    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)
    sysv     standard
    unix     standard
    unix95   standard
    unix98   standard

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=

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, 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)