PS(1) User Commands December 2011

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ps - report a snapshot of the current processes.

NAME

ps - report a snapshot of the current processes.

SYNOPSIS

ps [options]

DESCRIPTION

ps

displays information about a selection of the active processes. If you want a repetitive update of the selection and the displayed information, use

top(1)

instead.

This version of

ps

accepts several kinds of options:

Options of different types may be freely mixed, but conflicts can appear. There are some synonymous options, which are functionally identical, due to the many standards and

ps

implementations that this

ps

is compatible with.

Note that "ps -aux" is distinct from "psaux". The POSIX and UNIX standards require that "ps-aux" print all processes owned by a user named "x", as well as printing all processes that would be selected by the

-a

option. If the user named "x" does not exist, this

ps

may interpret the command as "psaux" instead and print a warning. This behavior is intended to aid in transitioning old scripts and habits. It is fragile, subject to change, and thus should not be relied upon.

By default,

ps

selects all processes with the same effective user ID (euid=EUID) as the current user and associated with the same terminal as the invoker. It displays the process ID (pid=PID), the terminal associated with the process (tname=TTY), the cumulated CPU time in [DD-]hh:mm:ss format (time=TIME), and the executable name (ucmd=CMD). Output is unsorted by default.

The use of BSD-style options will add process state (stat=STAT) to the default display and show the command args (args=COMMAND) instead of the executable name. You can override this with the

PS_FORMAT

environment variable. The use of BSD-style options will also change the process selection to include processes on other terminals (TTYs) that are owned by you; alternately, this may be described as setting the selection to be the set of all processes filtered to exclude processes owned by other users or not on a terminal. These effects are not considered when options are described as being "identical" below, so

-M

will be considered identical to Z and so on.

Except as described below, process selection options are additive. The default selection is discarded, and then the selected processes are added to the set of processes to be displayed. A process will thus be shown if it meets any of the given selection criteria.

EXAMPLES

To see every process on the system using standard syntax:

ps-e


ps-ef


ps-eF


ps-ely

To see every process on the system using BSD syntax:

psax


psaxu

To print a process tree:

ps-ejH


psaxjf

To get info about threads:

ps-eLf


psaxms

To get security info:

ps-eo euser,ruser,suser,fuser,f,comm,label


psaxZ


ps-eM

To see every process running as root (real&effectiveID) in user format:

ps-Uroot-urootu

To see every process with a user-defined format:

ps-eopid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm


psaxostat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm


ps-Aopid,tt,user,fname,tmout,f,wchan

Print only the process IDs of syslogd:

ps-Csyslogd-opid=

Print only the name of PID 42:

ps-p42-ocomm=

SIMPLE PROCESS SELECTION

a
Lift the BSD-style "only yourself" restriction, which is imposed upon the set of all processes when some BSD-style (without "-") options are used or when the

ps

personality setting is BSD-like. The set of processes selected in this manner is in addition to the set of processes selected by other means. An alternate description is that this option causes

ps

to list all processes with a terminal (tty), or to list all processes when used together with the

x

option.
-A
Select all processes. Identical to

-e.

-a
Select all processes except both session leaders (see

getsid(2))

and processes not associated with a terminal.
-d
Select all processes except session leaders.
--deselect
Select all processes except those that fulfill the specified conditions (negates the selection). Identical to

-N.

-e
Select all processes. Identical to

-A.

g
Really all, even session leaders. This flag is obsolete and may be discontinued in a future release. It is normally implied by the

a

flag, and is only useful when operating in the sunos4 personality.
-N
Select all processes except those that fulfill the specified conditions (negates the selection). Identical to

--deselect.

T
Select all processes associated with this terminal. Identical to the

t

option without any argument.
r
Restrict the selection to only running processes.
x
Lift the BSD-style "must have a tty" restriction, which is imposed upon the set of all processes when some BSD-style (without "-") options are used or when the

ps

personality setting is BSD-like. The set of processes selected in this manner is in addition to the set of processes selected by other means. An alternate description is that this option causes

ps

to list all processes owned by you (same EUID as

ps),

or to list all processes when used together with the

a

option.

PROCESS SELECTION BY LIST

These options accept a single argument in the form of a blank-separated or comma-separated list. They can be used multiple times. For example: ps-p"12"-p3,4
-123
Identical to --pid123.
123
Identical to --pid123.
-Ccmdlist
Select by command name. This selects the processes whose executable name is given in

cmdlist.

-Ggrplist
Select by real group ID (RGID) or name. This selects the processes whose real group name or ID is in the

grplist

list. The real group ID identifies the group of the user who created the process, see

getgid(2).

-ggrplist
Select by session OR by effective group name. Selection by session is specified by many standards, but selection by effective group is the logical behavior that several other operating systems use. This

ps

will select by session when the list is completely numeric (assessions are). Group ID numbers will work only when some group names are also specified. See the

-s

and

--group

options.
--Groupgrplist
Select by real group ID (RGID) or name. Identical to

-G.

--groupgrplist
Select by effective group ID (EGID) or name. This selects the processes whose effective group name or ID is in

grouplist.

The effective group ID describes the group whose file access permissions are used by the process (see

getegid(2)).

The

-g

option is often an alternative to

--group.

ppidlist
Select by process ID. Identical to

-p

and

--pid.

-ppidlist
Select by PID. This selects the processes whose process ID numbers appear in

pidlist.

Identical to

p

and

--pid.

--pid pidlist
Select by processID. Identical to

-p

and

p.

--ppidpidlist
Select by parent process ID. This selects the processes with a parent processID in

pidlist.

That is, it selects processes that are children of those listed in

pidlist.

-ssesslist
Select by session ID. This selects the processes with a session ID specified in

sesslist.

--sidsesslist
Select by sessionID. Identical to

-s.

tttylist
Select by tty. Nearly identical to

-t

and

--tty,

but can also be used with an empty

ttylist

to indicate the terminal associated with

ps.

Using the

T

option is considered cleaner than using

t

with an empty

ttylist.

-tttylist
Select by tty. This selects the processes associated with the terminals given in

ttylist.

Terminals (ttys, or screens for text output) can be specified in several forms: /dev/ttyS1, ttyS1, S1. A plain "-" may be used to select processes not attached to any terminal.
--ttyttylist
Select by terminal. Identical to

-t

and

t.

Uuserlist
Select by effective user ID (EUID) or name. This selects the processes whose effective user name or ID is in

userlist.

The effective user ID describes the user whose file access permissions are used by the process (see

geteuid (2)).

Identical to

-u

and

--user.

-Uuserlist
Select by real user ID (RUID) or name. It selects the processes whose real user name or ID is in the

userlist

list. The real user ID identifies the user who created the process, see

getuid(2).

-uuserlist
Select by effective user ID (EUID) or name. This selects the processes whose effective user name or ID is in

userlist.

The effective user ID describes the user whose file access permissions are used by the process (see

geteuid(2)).

Identical to

U

and

--user.

--Useruserlist
Select by real user ID (RUID) or name. Identical to

-U.

--useruserlist
Select by effective user ID (EUID) or name. Identical to

-u

and

U.

OUTPUT FORMAT CONTROL

These options are used to choose the information displayed by

ps.

The output may differ by personality.

-c
Show different scheduler information for the

-l

option.
--context
Display security context format (for SE Linux).
-f
Do full-format listing. This option can be combined with many other UNIX-style options to add additional columns. It also causes the command arguments to be printed. When used with

-L,

the NLWP (number of threads) and LWP (thread ID) columns will be added. See the

c

option, the format keyword

args,

and the format keyword

comm.

-F
Extra full format. See the

-f

option, which

-F

implies.
--formatformat
user-defined format. Identical to

-o

and

o.

j
BSD job control format.
-j
Jobs format.
l
Display BSD long format.
-l
Long format. The

-y

option is often useful with this.
-M
Add a column of security data. Identical to

Z

(for SE Linux).
Oformat
is preloaded

o

(overloaded). 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 (sorting or formatting), specify the option in some other way (e.g. with

-O

or

--sort).

When used as a formatting option, it is identical to

-O,

with the BSD personality.
-Oformat
Like

-o,

but preloaded with some default columns. Identical to -opid,:format,:state,:tname,:time,:command or -opid,:format,:tname,:time,:cmd, see

-o

below.
oformat
Specify user-defined format. Identical to

-o

and

--format.

-oformat
User-defined format.

format

is a single argument in the form of a blank-separated or comma-separated list, which offers a way to specify individual output columns. The recognized keywords are described in the

STANDARD FORMAT SPECIFIERS

section below. 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.
s
Display signal format.
u
Display user-oriented format.
v
Display virtual memory format.
X
Register format.
-y
Do not show flags; show rss in place of addr. This option can only be used with

-l.

Z
Add a column of security data. Identical to

-M

(for SE Linux).

OUTPUT MODIFIERS

c
Show the true command name. This is derived from the name of the executable file, rather than from the argv value. Command arguments and any modifications to them are thus not shown. This option effectively turns the

args

format keyword into the

comm

format keyword; it is useful with the

-f

format option and with the various BSD-style format options, which all normally display the command arguments. See the

-f

option, the format keyword

args,

and the format keyword

comm.

--colsn
Set screen width.
--columnsn
Set screen width.
--cumulative
Include some dead child process data (as a sum with the parent).
e
Show the environment after the command.
f
ASCII art process hierarchy (forest).
--forest
ASCII art process tree.
h
No header. (or, one header per screen in the BSD personality). The

h

option is problematic. Standard BSD

ps

uses this option to print a header on each page of output, but older Linux

ps

uses this 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 or disable headers entirely, respectively.
-H
Show process hierarchy (forest).
--headers
Repeat header lines, one per page of output.
kspec
Specify sorting order. Sorting syntax is [+|-]key[,[+|-]key[,...]]. Choose a multi-letter key from the

STANDARD FORMAT SPECIFIERS

section. The "+" is optional since default direction is increasing numerical or lexicographic order. Identical to

--sort.

  • Examples:

    ps jaxkuid,-ppid,+pid


    ps axk comm o comm,args


    ps kstart_time -ef

--linesn
Set screen height.
-nnamelist
Set namelist file. Identical to

N.

The namelist file is needed for a proper WCHAN display, and must match the current Linux kernel exactly for correct output. Without this option, the default search path for the namelist is:
  • $PS_SYSMAP
    $PS_SYSTEM_MAP
    /proc/*/wchan
    /boot/System.map-$(uname-r)
    /boot/System.map
    /lib/modules/$(uname-r)/System.map
    /usr/src/linux/System.map
    /System.map
n
Numeric output for WCHAN and USER (including all types of UID and GID).
Nnamelist
Specify namelist file. Identical to

-n,

see

-n

above.
--no-headers
Print no header line at all.

--no-heading

is an alias for this option.
Oorder
Sorting order (overloaded). 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 (sorting or formatting), specify the option in some other way (e.g. with

-O

or

--sort).

  • For sorting, obsolete BSD

    O

    option syntax is O[+|-]k1[,[+|-]k2[,...]]. It orders the processes listing according to the multilevel sort specified by the sequence of one-letter short keys

    k1,k2, ...

    described in the

    OBSOLETE SORT KEYS

    section below. The"+" is currently optional, merely re-iterating the default direction on a key, but may help to distinguish an

    O

    sort from an

    O

    format. The "-" reverses direction only on the key it precedes.
--rowsn
Set screen height.
S
Sum up some information, such as CPU usage, from dead child processes into their parent. This is useful for examining a system where a parent process repeatedly forks off short-lived children to do work.
--sortspec
Specify sorting order. Sorting syntax is [+|-]key[,[+|-]key[,...]]. Choose a multi-letter key from the

STANDARD FORMAT SPECIFIERS

section. The "+" is optional since default direction is increasing numerical or lexicographic order. Identical to

k.

For example:

ps jax --sort=:uid,:-ppid,:+pid

w
Wide output. Use this option twice for unlimited width.
-w
Wide output. Use this option twice for unlimited width.
--widthn
Set screen width.

THREAD DISPLAY

H
Show threads as if they were processes.
-L
Show threads, possibly with LWP and NLWP columns.
m
Show threads after processes.
-m
Show threads after processes.
-T
Show threads, possibly with SPID column.

OTHER INFORMATION

--helpsection
Print a help message. The section argument can be one of simple, list, output, threads, misc or all. The argument can be shortened to one of the underlined letters as in: s|l|o|t|m|a.
--info
Print debugging info.
L
List all format specifiers.
V
Print the procps-ng version.
-V
Print the procps-ng version.
--version
Print the procps-ng version.

NOTES

This

ps

works by reading the virtual files in /proc. This

ps

does not need to be setuid kmem or have any privileges to run. Do not give this

ps

any special permissions.

This

ps

needs access to namelist data for proper WCHAN display. For kernels prior to 2.6, the System.map file must be installed.

CPU usage is currently expressed as the percentage of time spent running during the entire lifetime of a process. This is not ideal, andit does not conform to the standards that

ps

otherwise conforms to. CPU usage is unlikely to add up to exactly 100%.

The SIZE and RSS fields don't count some parts of a process including the page tables, kernel stack, struct thread_info, and struct task_struct. This is usually at least 20 KiB of memory that is always resident. SIZE is the virtual size of the process (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.

If the length of the username is greater than the length of the display column, the numeric user ID is displayed instead.

PROCESS FLAGS

The sum of these values is displayed in the "F" column, which is provided by the

flags

output specifier:
1
forked but didn't exec
4
used super-user privileges

PROCESS STATE CODES

Here are the different values that the

s,statandstate

output specifiers (header "STAT" or "S") will display to describe the state of a process:
D
uninterruptible sleep (usually IO)
R
running or runnable (on run queue)
S
interruptible sleep (waiting for an event to complete)
T
stopped, either by a job control signal or because it is being traced
W
paging (not valid since the 2.6.xx kernel)
X
dead (should never be seen)
Z
defunct ("zombie") process, terminated but not reaped by its parent

For BSD formats and when the

stat

keyword is used, additional characters may be displayed:

<
high-priority (not nice to other users)
N
low-priority (nice to other users)
L
has pages locked into memory (for real-time and custom IO)
s
is a session leader
l
is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+
is in the foreground process group

OBSOLETE SORT KEYS

These keys are used by the BSD

O

option (when it is used for sorting). The GNU

--sort

option doesn't use these keys, but the specifiers described below in the

STANDARD FORMAT SPECIFIERS

section. 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 (e.g. sorting on tty will sort into device number, not according to the terminal name displayed). Pipe

ps

output into the

sort(1)

command if you want to sort the cooked values.

.TS

l l lw(3i). KEY LONG DESCRIPTION c cmd simple name of executable C pcpu cpu utilization 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 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 device number of the controlling tty T start_time time process was started U uid user ID number u user user name v vsize total VM size in KiB y priority kernel scheduling priority

.TE

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". The

NORMAL

codes are described in the next section.

.TS

l l l. 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

.TE

STANDARD FORMAT SPECIFIERS

Here are the different keywords that may be used to control the output format (e.g. with option

-o)

or to sort the selected processes with the GNU-style

--sort

option.

For example:

ps -eo pid,:user,:args --sort user

This version of

ps

tries to recognize most of the keywords used in other implementations of

ps.

The following user-defined format specifiers may contain spaces:

args,cmd,comm,command,fname,ucmd,ucomm,

lstart,bsdstart,start.

Some keywords may not be available for sorting.

.TS

expand; lB1 lB1 lBw(n[ColSize]n) lB1 l1 l. CODE HEADER DESCRIPTION

%cpu %CPU T{ cpu utilization of the process in "##.#" format. Currently, it is the CPU time used divided by the time the process has been running (cputime/realtime ratio), expressed as a percentage. It will not add up to 100% unless you are lucky. (alias

pcpu).

T}

%mem %MEM T{ ratio of the process's resident set size to the physical memory on the machine, expressed as a percentage. (alias

pmem).

T}

args COMMAND T{ command with all its arguments as a string. Modifications to the arguments may be shown. The output in this column may contain spaces. A process marked <defunct> is partly dead, waiting to be fully destroyed by its parent. Sometimes the process args will be unavailable; when this happens,

ps

will instead print the executable name in brackets. (alias

cmd,command).

See also the

comm

format keyword, the

-f

option, and the

c

option.
When specified last, this column will extend to the edge of the display. If

ps

can not determine display width, as when output is redirected (piped) into a file or another command, the output width is undefined (it may be 80, unlimited, determined by the

TERM

variable, and so on). The

COLUMNS

environment variable or

--cols

option may be used to exactly determine the width in this case. The

w

or

-w

option may be also be used to adjust width. T}

blocked BLOCKED T{ mask of the blocked signals, see

signal(7).

According to the width of the field, a 32 or 64-bit mask in hexadecimal format is displayed. (alias

sig_block,sigmask).

T}

bsdstart START T{ time the command started. If the process was started less than 24 hours ago, the output format is "HH:MM", else it is " Mmm:SS" (where Mmm is the three letters of the month). See also

lstart,start,start_time, and stime.

T}

bsdtime TIME T{ accumulated cpu time, user + system. The display format is usually "MMM:SS", but can be shifted to the right if the process used more than 999 minutes of cpu time. T}

c C T{ processor utilization. Currently, this is the integer value of the percent usage over the lifetime of the process. (see

%cpu).

T}

caught CAUGHT T{ mask of the caught signals, see

signal(7).

According to the width of the field, a 32 or 64 bits mask in hexadecimal format is displayed. (alias

sig_catch,sigcatch).

T}

cgroup CGROUP T{ display control groups to which the process belongs. T}

class CLS T{ scheduling class of the process. (alias

policy,cls).

Field's possible values are:

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... (see section

PERSONALITY

below).
CMD_ENV
Set to one of posix, old, linux, bsd, sun, digital... (see section

PERSONALITY

below).
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. You may set this to a format string of the type used for the

-o

option. The

DefSysV

and

DefBSD

values are particularly useful.
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".
POSIX2
When set to "on", acts as

POSIXLY_CORRECT.

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.

PERSONALITY

.TS

l l. 390 like the OS/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 Tru64 (was DigitalUnix, was OSF/1) 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) os390 like OS/390 Open Edition ps posix standard s390 like OS/390 Open Edition ps sco like SCO ps sgi like Irix ps solaris2 like Solaris 2+ (SunOS 5) ps sunos4 like SunOS 4 (Solaris 1) ps (totally non-standard) svr4 standard sysv standard tru64 like Tru64 (was Digital Unix, was OSF/1) ps unix standard unix95 standard unix98 standard

.TE

SEE ALSO

pgrep(1),

pstree(1),

top(1),

proc(5).

STANDARDS

This

ps

conforms to:

AUTHOR

ps

was originally written by

.UR [email protected]\:fwi.\:uva.\:nl

Branko Lankester

.UE .

.UR [email protected]\:redhat.\:com

Michael K. Johnson

.UE

re-wrote it significantly to use the proc filesystem, changing a few things in the process.

.UR [email protected]\:nyx.\:cs.\:du.\:edu

Michael Shields

.UE

added the pid-list feature.

.UR [email protected]\:bbn.\:com

Charles Blake

.UE

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.

.UR [email protected]\:users.\:sf.\:net

Albert Cahalan

.UE

rewrote ps for full Unix98 and BSD support, along with some ugly hacks for obsolete and foreign syntax.

Please send bug reports to

.UR [email protected]\:freelists.\:org

.UE .

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