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.Dd $Mdocdate: July 25 2018 $
.Dt TOP 1
.Os
.Sh NAME
.Nm top
.Nd display and update information about the top CPU processes
.Sh SYNOPSIS
.Nm top
.Bk -words
.Op Fl 1bCHIinqSu
.Op Fl d Ar count
.Op Fl g Ar string
.Op Fl o Ar field
.Op Fl p Ar pid
.Op Fl s Ar time
.Op Fl U Oo - Oc Ns Ar user
.Op Ar number
.Ek
.Sh DESCRIPTION
.Nm
displays the top processes on the system and periodically updates this
information.
If standard output is an intelligent terminal (see below) then
as many processes as will fit on the terminal screen are displayed
by default.
Otherwise, a good number of them are shown (around 20).
Raw CPU percentage is used to rank the processes.
If
.Ar number
is given, then the top
.Ar number
processes will be displayed instead of the default.
.Pp
.Nm
makes a distinction between terminals that support advanced capabilities
and those that do not.
This distinction affects the choice of defaults for certain options.
In the remainder of this document, an
.Em intelligent
terminal is one that supports cursor addressing, clear screen, and clear
to end of line.
Conversely, a
.Em dumb
terminal is one that does not support such features.
If the output of
.Nm
is redirected to a file, it acts as if it were being run on a dumb
terminal.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl 1
Display combined CPU statistics for all processors on a single line
instead of one line per CPU.
If there are more than 8 CPUs detected in the system this option
is automatically enabled.
.It Fl b
Use
.Em batch
mode.
In this mode, all input from the terminal is ignored.
Interrupt characters (such as
.Ql ^C
and
.Ql ^\e )
still have an effect.
This is the default on a dumb terminal, or when the output is not a terminal.
.It Fl C
Show command line arguments
as well as the process itself.
.It Fl d Ar count
Show only
.Ar count
displays, then exit.
A display is considered to be one update of the screen.
This option allows the user to select the number of displays
to be shown before
.Nm
automatically exits.
For intelligent terminals, no upper limit is set.
The default is 1 for dumb terminals.
.It Fl g Ar string
Display only processes that contain
.Ar string
in their command name.
If displaying of arguments is enabled, the arguments are searched too.
.It Fl H
Show process threads in the display.
Normally, only the main process is shown.
This option makes all threads visible.
.It Fl I
Do not display idle processes.
By default,
.Nm
displays both active and idle processes.
.It Fl i
Use
.Em interactive
mode.
In this mode, any input is immediately read for processing.
See the section on
.Sx INTERACTIVE MODE
for an explanation of which keys perform what functions.
After the command
is processed, the screen will immediately be updated, even if the command was
not understood.
This mode is the default when standard output is an intelligent terminal.
.It Fl n
Use
.Em non-interactive
mode.
This is identical to
.Em batch
mode.
.It Fl o Ar field
Sort the process display area using the specified
.Ar field
as the primary key.
The field name is the name of the column as seen in the output,
but in lower case.
The
.Ox
version of
.Nm
supports
.Ar cpu ,
.Ar size ,
.Ar res ,
.Ar time ,
.Ar pri ,
.Ar pid ,
and
.Ar command .
.It Fl p Ar pid
Show only the process
.Ar pid .
.It Fl q
Renice
.Nm
to \-20 so that it will run faster.
This can be used when the system is
being very sluggish to improve the possibility of discovering the problem.
This option can only be used by root.
.It Fl S
Show system processes in the display.
Normally, system processes such as the pager and the swapper are not shown.
This option makes them visible.
.It Fl s Ar time
Set the delay between screen updates to
.Ar time
seconds.
The value may be fractional, to permit delays of less than 1 second.
The default delay between updates is 5 seconds.
.It Fl U Oo - Oc Ns Ar user
Show only those processes owned by
.Ar user .
The prefix
.Sq -
hides processes owned by that user.
This option currently only accepts usernames and does not understand
UID numbers.
.It Fl u
Do not take the time to map UID numbers to usernames.
Normally,
.Nm
will read as much of the password database as is necessary to map
all the user ID numbers it encounters into login names.
This option
disables all that, while possibly decreasing execution time.
The UID numbers are displayed instead of the names.
.El
.Pp
Both
.Ar count
and
.Ar number
fields can be specified as
.Li infinite ,
indicating that they can stretch as far as possible.
This is accomplished by using any proper prefix of the keywords
.Li infinity ,
.Li maximum ,
or
.Li all .
The default for
.Ar count
on an intelligent terminal is, in fact,
.Li infinity .
.Pp
The environment variable
.Ev TOP
is examined for options before the command line is scanned.
This enables a user to set his or her own defaults.
The number of processes to display
can also be specified in the environment variable
.Ev TOP .
.Pp
The options
.Fl I ,
.Fl S ,
and
.Fl u
are actually toggles.
A second specification of any of these options
will negate the first.
Thus a user who has the environment variable
.Ev TOP
set to
.Dq -I
may use the command
.Dq top -I
to see idle processes.
.Sh INTERACTIVE MODE
When
.Nm
is running in
.Em interactive mode ,
it reads commands from the terminal and acts upon them accordingly.
In this mode, the terminal is put in
.Dv CBREAK ,
so that a character will be processed as soon as it is typed.
Almost always, a key will be pressed when
.Nm
is between displays; that is, while it is waiting for
.Ar time
seconds to elapse.
If this is the case, the command will be
processed and the display will be updated immediately thereafter
(reflecting any changes that the command may have specified).
This happens even if the command was incorrect.
If a key is pressed while
.Nm
is in the middle of updating the display, it will finish the update and
then process the command.
Some commands require additional information,
and the user will be prompted accordingly.
While typing this information
in, the user's erase and kill keys (as set up by the command
.Xr stty 1 )
are recognized, and a newline terminates the input.
.Pp
These commands are currently recognized (^L refers to control-L):
.Bl -tag -width XxXXXX
.It h | \&?
Display a summary of the commands (help screen).
.It ^L
Redraw the screen.
.It <space>
Update the screen.
.It q
Quit
.Nm .
.El
.Bl -tag -width XxXXXX
.It +
Reset any filters put in place by the
.Sq g ,
.Sq p ,
and
.Sq u
interactive commands,
or their command line equivalents,
or any process highlighting put in place by the
.Sq P
interactive command.
.It 1
Toggle the display of per CPU or combined CPU statistics.
.It C
Toggle the display of process command line arguments.
.It d Ar count
Show only
.Ar count
displays,
then exit.
.It e
Display a list of system errors (if any) generated by the last
.Li kill
or
.Li renice
command.
.It g Ar string
Display only processes that contain
.Ar string
in their command name.
If displaying of arguments is enabled, the arguments are searched too.
.Sq g+
shows all processes.
.It H
Toggle the display of process threads.
.It I | i
Toggle the display of idle processes.
.It Xo k
.Op - Ns Ar sig
.Ar pid
.Xc
Send signal
.No - Ns Ar sig
.Pf ( Dv TERM
by default) to process
.Ar pid .
This acts similarly to the command
.Xr kill 1 .
.It n\*(Ba# Ar count
Show
.Ar count
processes.
.It o Ar field
Sort the process display area using the specified
.Ar field
as the primary key.
Values are the same as for the
.Fl o
flag, as detailed above.
.It P Ar pid
Highlight a specific process, selected by
.Ar pid .
.Sq P+
removes process highlighting.
.It p Ar pid
Show only the process
.Ar pid .
.Sq p+
shows all processes.
.It r Ar count pid
Change the priority (the
.Em nice )
of a list of processes to
.Ar count
for process
.Ar pid .
This acts similarly to the command
.Xr renice 8 .
.It S
Toggle the display of system processes.
.It s Ar time
Set the delay between screen updates to
.Ar time
seconds.
.It u Oo - Oc Ns Ar user
Show only those processes owned by
.Ar user .
.Sq u+
shows processes belonging to all users.
The
.Sq -
prefix hides processes belonging to a single
.Ar user .
.El
.Sh THE DISPLAY
.\" The actual display varies depending on the specific variant of Unix
.\" that the machine is running.  This description may not exactly match
.\" what is seen by top running on this particular machine.  Differences
.\" are listed at the end of this manual entry.
.\" .Pp
The top few lines of the display show general information
about the state of the system, including
.\" the last process ID assigned to a process,
.\" (on most systems),
the three load average numbers,
the hostname,
the current time,
the number of existing processes,
the number of processes in each state
(starting, running, idle, stopped, zombie, dead, and on processor),
and a percentage of time spent in each of the processor states
(user, nice, system, spinning, interrupt, and idle).
It also includes information about physical and virtual memory allocation.
The load average numbers give the number of jobs in the run queue averaged
over 1, 5, and 15 minutes.
.Pp
The remainder of the screen displays information about individual
processes.
This display is similar in spirit to
.Xr ps 1
but it is not exactly the same.
The following fields are displayed:
.Bl -tag -width USERNAME -offset indent
.It PID
The process ID.
.It USERNAME
The name of the process's owner.
.It TID
The thread ID, used instead of USERNAME if
.Fl H
is specified.
.It UID
Used instead of USERNAME if
.Fl u
is specified.
.It PRI
The current priority of the process.
.It NICE
The nice amount (in the range \-20 to 20).
.It SIZE
The total size of the process (the text, data, and stack segments).
.It RES
The current amount of resident memory.
.It STATE
The current state (one of
.Li start ,
.Li run ,
.Li sleep ,
.Li stop ,
.Li idle ,
.Li zomb ,
.Li dead ,
or
.Li onproc ) .
On multiprocessor systems, this is followed by a slash and the CPU
number on which the process is bound.
.It WAIT
A description of the wait channel the process is sleeping on if it's
asleep.
.It TIME
The number of system and user CPU seconds that the process has used.
.It CPU
The raw percentage of CPU usage and the default field on which the
display is sorted.
.It COMMAND
The name of the command that the process is currently running.
(If the process is swapped out, this column is enclosed by angle
brackets.)
.El
.Sh ENVIRONMENT
.Bl -tag -width Ev
.It Ev TOP
User-configurable defaults for options.
.El
.Sh FILES
.Bl -tag -width "/etc/passwdXXX" -compact
.It Pa /dev/kmem
kernel memory
.It Pa /dev/mem
physical memory
.It Pa /etc/passwd
used to map user ID to user
.It Pa /bsd
kernel image
.El
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr kill 1 ,
.Xr netstat 1 ,
.Xr ps 1 ,
.Xr stty 1 ,
.Xr systat 1 ,
.Xr mem 4 ,
.Xr iostat 8 ,
.Xr pstat 8 ,
.Xr renice 8 ,
.Xr vmstat 8
.Sh AUTHORS
.An William LeFebvre ,
EECS Department, Northwestern University
.Sh CAVEATS
As with
.Xr ps 1 ,
.Nm
only provides snapshots of a constantly changing system.