NAME

ps − Displays current process status

SYNOPSIS

ps [−aAdejflm] [−oO specifier][=header],...  [−g glist] [−p plist] [−s slist] [−t tlist]
[−u ulist] [-U ulist] [-n nlist]

BSD Compatible Syntax

ps [aAeghjlLmsSTuvwx] [oO specifier][=header],...  [t tty] [process_number]

The ps command displays the current process status. 

DESCRIPTION

While ps is a fairly accurate snapshot of the system, ps cannot begin and finish a snapshot as fast as some processes change state.  At times there may be minor discrepancies. 

The ps command can be used on multiprocessing systems and for querying the system state of realtime applications for their POSIX priority and scheduling policy. 

Output formats for each process include the process ID (pid), control terminal of the process (tname), CPU time used by the process (cputime) (this includes both user and system time), the state of the process (state), and an indication of the command that is running (command). The abbreviation tty indicates a terminal. 

The state is given by a sequence of letters, for example, RWN.  The first letter indicates the status of the process:

RRunnable process. 

UUninterruptible sleeping process. 

SProcess sleeping for less than about 20 seconds. 

IIdle (sleeping longer than about 20 seconds) process. 

TStopped process. 

HHalted process. 

Additional characters after these, if any, indicate additional state information:

WProcess is swapped out (shows a blank space if the process is loaded (in-core)). 

>Process has specified a soft limit on memory requirements and is exceeding that limit; such a process is (necessarily) not swapped. 

An additional letter may indicate whether a process is running with altered CPU scheduling priority (nice):

NProcess priority is reduced. 

<Process priority has been artificially raised. 

+Process is a process group leader with a controlling tty. 

Format Specifiers

The following list contains all format specifiers that can be used with ps:

Specifier	Header	Meaning
command	COMMAND	Command arguments (and environment with BSD e flag)
ucomm	COMMAND	Command name for accounting
logname	LOGNAME	User’s login name
flag	F	Process flags
status	STATUS	Process status
uid	UID	Process user ID (effective UID)
ruid	RUID	Process user ID (real UID)
svuid	SVUID	Saved process user ID
rgid	RGID	Process group (real GID)
svgid	SVGID	Saved process group ID
pid	PID	Process ID
ppid	PPID	Parent process ID
cp	CP	Short-term CPU utilization factor (used in scheduling)
wchan	WCHAN	Address of event on which a process is waiting (an address in the system).  A symbol is chosen that classifies the address, if available, from the system; otherwise, it is printed numerically.
nwchan	WCHAN	In this case, the initial part of the address is trimmed off and is printed hexadecimally, for example, 0x80004000 prints as 4000.
cursig	CURSIG	Current signal
sig	PENDING	Signals pending to this process
sigmask	BLOCKED	Current signal mask
sigignore	IGNORED	Signals being ignored
sigcatch	CAUGHT	Signals being caught
user	USER	Username
ruser	RUSER	User ID
group	GROUP	Group name
rgroup	RGROUP	Real group name
pgid	PGID	Process group ID
jobc	JOBC	Current count of processes qualifying PGID for job control
sess	SESS	Session ID
tdev	TDEV	Major/minor device for controlling tty
tname	TT	Controlling tty device name
longtname	TT	Long controlling tty device name
tpgid	TPGID	Foreground process group associated with tty
tsession	TSESS	Session associated with tty
state	S	Symbolic process status
pri	PRI	Process priority
psxpri	PPR	POSIX scheduling priority
usrpri	UPR	Base scheduling priority
nice	NI	Process scheduling increment (see the setpriority() call).
vsize	VSZ	Process virtual address size
rssize	RSS	Real memory (resident set) size of the process (in 1024 byte units)
u_procp	UPROCP	Address of process in user area
umask	UMASK	Process umask
acflag	ACFLG	Process accounting flag
start	STARTED	Start time of process.  If start time was more than 24 hours ago, gives the date.
lstart	STARTED	Start time and date of process
cputime	TIME	Current CPU time used
usertime	USER	Time spent in user space
systime	SYSTEM	Time spent in system
pcpu	%CPU	Percent CPU usage.  This is a decaying average of up to a minute of previous (real) time.  Since the time base over which this is computed varies (since processes may be very young), it is possible for the sum of all %CPU fields to exceed 100%.
pmem	%MEM	Percent real memory usage
sl	SL	Sleep time
pagein	PAGEIN	Number of disk I/Os resulting from references by the process to pages not loaded in core.
minflt	MINFLT	Page reclaims
majflt	MAJFLT	Page faults
nswap	NSWAP	Swaps
inblock	INBLK	Block input operations
oublock	OUBLK	Block output operations
msgsnd	MSGSND	Messages sent
msgrcv	MSGRCV	Messages received
nsignals	NSIGS	Signals received
nvcsw	VCSW	Voluntary context switches
nivcsw	IVCSW	Involuntary context switches
scount	SCNT	Suspend count
psr	PSR	Current processor (~ means bound)
pset	PSET	Current processor set (^ means bound)
policy	POL	Current scheduling policy

Compound format specifiers are made up of groups of individual format specifiers, as follows:

Specifier	Meaning
RUSAGE	minflt, majflt, nswap, inblock, oublock, msgsnd, msgrcv, nsigs, nvcsw, nivcsw
THREAD	user, %cpu, pri, scnt, wchan, usertime, systime
DFMT (default printing format)	pid, tname, state, cputime, command
LFMT (BSD l format)	uid, pid, ppid, cp, pri, nice, vsz, rss, wchan, state, tname, cputime, command
JFMT (j format)	user, pid, ppid, pgid, sess, jobc, state, tname, cputime, command
SFMT (BSD s format)	uid, pid, cursig, sig, sigmask, sigignore, sigcatch, stat, tname, command
VFMT (BSD v format)	pid, tt, state, time, sl, pagein, vsz, rss, %cpu, %mem, command
UFMT (BSD u format)	uname, pid, %cpu, %mem, vsz, rss, tt, state, start, time, command
F5FMT (f format)	uname, pid, ppid, %cpu, start, tt, time, command
L5FMT (l format)	f, state, uid, pid, ppid, %cpu, pri, nice, rss, wchan, tt, time, ucomm
FL5FMT (lf format)	f, state, uid, pid, ppid, %cpu, pri, nice, rss, wchan, start, time, command
process_flags	Flags associated with process as in <sys/proc.h>
SCHED	user %cpu pri usrpri nice psxpri psr policy pset

The flags associated with process as in <sys/proc.h> (see process_flags in the preceding table) are as follows:

Symbolic Constant	Flag Value (Hex)	Meaning
SLOAD	0x00000001	In core
SSYS	0x00000002	Swapper or pager process
STRC	0x00000010	Process is being traced
SOMASK	0x00000200	Restore old mask after taking signal
SWEXIT	0x00000400	Working on exiting
SPHYSIO	0x00000800	Doing physical I/O
SPAGV	0x00008000	Init data space on demand, from vnode
SSEQL	0x00010000	User warned of sequential vm behavior
SUANOM	0x00020000	User warned of random vm behavior
STIMO	0x00040000	Timing out during sleep
SOWEUPC	0x00200000	Owe process an addupc() call
SCTTY	0x00800000	Has a controlling terminal
SXONLY	0x02000000	Process image read-protected
SNOCLDSTOP	0x40000000	No SIGCHLD when children stop
SNOCLDWAIT	0X20000000	No zombies when children exist
SEXEC	0x80000000	Process called exec

<defunct>
A process that has exited but whose parent process has not waited for it is marked <defunct>. 

<errorA process for which user area information could not be obtained due to a shortage of system memory. 

<exiting>
A process that is blocked trying to exit is marked <exiting>. 

The ps program examines memory to get the filename and arguments given when the process was created.  The method is inherently somewhat unreliable because a process can destroy this information, so the names cannot be counted on too much. 

FLAGS

The following flags can be used with ps:

−aPrints information to standard output about all processes, except the session leaders and processes not associated with a terminal. 

−AWrites information for all processes. 

−dPrints information to standard output about all processes, except the session leaders. 

−ePrints information to standard output about all processes.  Equivalent to -A. 

−fGenerates a full listing. 

−g glistPrints only information about processes that are in the process groups listed in glist.  The glist is a list of process-group identifiers enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces (or tabs), or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists.  or more spaces (or tabs), or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

-G glistWrites information for processes whose real group ID numbers or names are given in glist.  The glist is a list of process-group identifiers enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces (or tabs), or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

−jProduces job control information, with fields specified for user, pid, ppid, pgid, sess, jobc, state, tname, time and command. 

−lGenerates a long listing. 

−mPrints all threads in a task, if the task has more than one. 

−o specifier[=header],...
Specifies a list of format specifiers to describe the output format.

−O specifier[=header],...
Same as o, except it displays the fields specified by pid, state, tname, time, and command in addition to the specifiers supplied on the command line. 

-n nlistHistorically, used to specify an alternative system file name list, nlist, in place of the default. The name list concept (see the nlist(3) reference page) does not apply to the Digital UNIX ps command; consequently, the −n flag is ignored. 

−p plistDisplays only information about processes with the process numbers specified in plist.  The plist argument is either a list of process ID numbers or a list of process ID numbers enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces (or tabs), or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

−rEnables warning messages. 

−s slistDisplays information about processes belonging to the sessions specified in slist.  The slist argument is either a list of session ID numbers or a list of session ID numbers enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces (or tabs), or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

−t tlistDisplays only information about processes associated with the terminals listed in tlist.  The tlist argument is either a list of terminal identifiers or a list of terminal identifiers enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces, or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

Terminal identifiers must be in one of two forms:

     1.The device’s filename

     2.The device’s digit identifier, if the device’s filename begins with tty

−u ulistDisplays only information about processes with the user ID numbers or login names specified in ulist.  The ulist argument is either a list of user IDs or a list of user IDs enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces, or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

In the listing, ps displays the numerical user ID unless the −f flag is used; then it displays the login name. 

-U ulistWrites information for processes whose real user ID numbers or login names are given in ulist.  The ulist argument is either a list of user IDs or a list of user IDs enclosed in " " (double quotes) and separated from one another by a comma or one or more spaces, or both.  Because of the way the shell treats spaces and tabs, you need to quote space-separated lists. 

The following BSD compatible flags can be used with ps (note that these flags are not prefixed with a − (dash) character):

aAsks for information regarding processes associated with terminals (ordinarily only one’s own processes are displayed). 

AIncreases the argument space. 

eAsks for the environment to be printed, as well as the arguments to the command. 

gAsks for all processes.  Without this flag, ps only prints interesting processes.  Processes are deemed to be uninteresting if they are process group leaders.  This normally eliminates top-level command interpreters and processes waiting for users to log in on free terminals. 

hRepeats the header after each screenful of information. 

jProduces job control information, with fields specified by user, ppid, pgid, sess, and jobc. 

lAsks for a detailed list, with fields specified by ppid, cp, pri, nice, vsize, rssize and wchan. 

LLists all available format specifiers. 

mPrints all threads in a task, if the task has more than one. 

o specifier[=header],...
Specifies a list of format specifiers to describe the output format.

O specifier[=header],...
Same as o, except it displays the fields specified by pid, state, tname, cputime, and comm in addition to the specifiers supplied on the command line. 

sGives signal states of the processes, with fields specified by uid, cursig, sig, sigmask, sigignore, and sigcatch. 

SPrints usage summaries (total usage of a command, as opposed to current usage). 

tttyLists only processes for the specified tty. 

TLists all processes on your tty. 

uProduces a user oriented output. This includes fields specified by user, pcpu, pmem, vsize, rssize, and start. 

vProduces a version of the output containing virtual memory statistics.  This includes fields specified by cputime, sl, pagein, vsize, rssize, pcpu, and pmem. 

wUses a wide output format (132 columns (bytes) rather than 80); if this flag is doubled (ww), uses an arbitrarily wide output.  This information determines how much of long commands to print. 

xAsks even about processes with no terminal. 

process_number
Restricts output to the specified process. This argument must be entered last on the command line.

NOTES

The following BSD compatible flags are not supported.  (You can reconstruct the output of these flags by using the appropriate format specifiers, however.) 

cDisplays the command name, as stored internally in the system for purposes of accounting, rather than the command arguments, which are kept in the process’s address space. 

nDisplays numeric output.  In a long listing, the wchan field is printed numerically rather than symbolically.  In a user listing, the user field is replaced by a uid field. 

RESTRICTIONS

When you enter a ps command while running an application that forks child processes, you might see some child processes listed as being in the <defunct> state after they have exited.  Processes in this state cannot be killed until the process that forked them is killed. 

The system puts exiting child processes in the <defunct> state if their parent process is still running and has not caught the SIGCHLD signal or executed a wait() system call. 

To avoid having users encounter this problem when they run your application, make sure that your program logic either catches the SIGCHLD signal or executes a wait() system call when spawning a child process. 

EXAMPLES

     1.To list all your processes, enter:

ps

     2.To list all processes, enter:

ps  −A

The BSD equivalent looks like this:

ps ax

     3.To list processes owned by specific users, enter:

ps  −f  −l  −ujim,jane,su

     4.To list processes associated with a specific tty, enter:

ps  −t console

The BSD equivalent looks like this:

ps tco

     5.To display only the pid, user, and comm information for all processes, enter:

ps −o pid,user,comm −A

     6.To display the parent process ID under the header PARENT, as well as the default headers (fields specified by pid, state, tname, time, command), enter:

ps −O ppid=PARENT

     7.The following ps command shows the use of the SCHED specifier on a two-processor system with two processor sets:

ps -O SCHED
PID USER %CPU PRI UPR NI PPR PSR POL PSET S   TTY        TIME COM
458 root  0.0  43  44  0  20   0  TS    0 I + console 0:01.34 csh
561 root  0.0  44  44  0  19   0  TS    0 I   ttyp0   0:00.42 csh
567 root  0.0  44  44  0  19   1  TS   ^2 I   ttyp0   0:00.03 runon
568 root  0.0  44  44  0  19   1  TS   ^2 I   ttyp0   0:00.03 sh
569 root  0.0  44  44  0  19   1  TS   ^2 S   ttyp0   0:00.31 csh
579 root  0.0  44  44  0  19  ~1  TS   ^2 S + ttyp0   0:00.03 runon
580 root  0.0  44  44  0  19  ~1  TS   ^2 S + ttyp0   0:00.03 sh
581 root  0.0  44  44  0  19  ~1  TS   ^2 R + ttyp0   0:00.06 ls -l

The display shows that all processes are running under the default timershare scheduling policy. Processes 458 and 561 are running unbound to processor 0 in processor set 0. Processes 567, 568, and 569, are running on processor 1 and are bound exclusively (^) to processor set 2. And processes 579, 580, and 581 are running bound to processor 1 (~) and are bound exclusively to processor set 2 (^). 

FILES

/devSearched to find tty names. 

RELATED INFORMATION

Commands: kill(1), w(1), runon(1)
Routines: sched_setscheduler(3), pthread_setscheduler(3)
File Formats: processor_sets(4)