- NetBSD Manual Pages
Powered by man-cgi (2021-06-01).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
top - display and update information about the top cpu processes
top [ -1CISTabcinqtuv ] [ -dcount ] [ -mmode ] [ -ofield ] [ -ppid ] [
-stime ] [ -Uusername ] [ number ]
Top 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
number is given, then the top number processes will be displayed
instead of the default.
Top makes a distinction between terminals that support advanced capa-
bilities and those that do not. This distinction affects the choice of
defaults for certain options. In the remainder of this document, an
"intelligent" terminal is one that supports cursor addressing, clear
screen, and clear to end of line. Conversely, a "dumb" terminal is one
that does not support such features. If the output of top is redi-
rected to a file, it acts as if it were being run on a dumb terminal.
Display per-cpu states on a multi-processor machine.
Turn off the use of color in the display.
Do not display idle processes. By default, top displays both
active and idle processes.
Show system processes in the display. Normally, system pro-
cesses such as the pager and the swapper are not shown. This
option makes them visible.
List all available color tags and the current set of tests used
for color highlighting, then exit.
Show all processes for as long as possible. This is shorthand
for "-d all all". This option is especially handy in batch
-b, -n, --batch
Use "batch" mode. In this mode, all input from the terminal is
ignored. Interrupt characters (such as ^C and ^\) still have an
effect. This is the default on a dumb terminal, or when the
output is not a terminal.
Show the full command line for each process. Default is to show
just the command name. This option is not supported on all
Use "interactive" mode. In this mode, any input is immediately
read for processing. See the section on "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.
Renice top to -20 so that it will run faster. This can be used
when the system is being very sluggish to improve the possibil-
ity of discovering the problem. This option can only be used by
Show individual threads on separate lines. By default, on sys-
tems which support threading, each process is shown with a count
of the number of threads. This option shows each thread on a
separate line. This option is not supported on all platforms.
Do not take the time to map uid numbers to usernames. Normally,
top will read as much of the file "/etc/passwd" as is necessary
to map all the user id numbers it encounters into login names.
This option disables all that, while possibly decreasing execu-
tion time. The uid numbers are displayed instead of the names.
Write version number information to stderr then exit immedi-
ately. No other processing takes place when this option is
used. To see current revision information while top is running,
use the help command "?".
-d count, --displays count
Show only 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 he wants to see before top auto-
matically exits. Any proper prefix of the words "infinity",
"maximum", or "all" can be used to indicate an infinite number
of displays. The default for intelligent terminals is infinity.
The default for dumb terminals is 1.
-m mode, --mode=mode
Start the display in an alternate mode. Some platforms support
multiple process displays to show additional process informa-
tion. The value mode is a number indicating which mode to dis-
play. The default is 0. On platforms that do not have multiple
display modes this option has no effect.
-o field, --sort-order=field
Sort the process display area on the specified field. The field
name is the name of the column as seen in the output, but in
lower case. Likely values are "cpu", "size", "res", and "time",
but may vary on different operating systems. Note that not all
operating systems support this option.
-p pid, --pid=pid
Only display the specified pid.
-s time, --delay=time
Set the delay between screen updates to time seconds. The
default delay between updates is 5 seconds.
-U username, --user=username
Show only those processes owned by username. This option cur-
rently only accepts usernames and will not understand uid num-
Both count and number fields can be specified as "infinite", indicating
that they can stretch as far as possible. This is accomplished by
using any proper prefix of the keywords "infinity", "maximum", or
"all". The default for count on an intelligent terminal is, in fact,
The environment variable 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 envi-
ronment variable TOP. The options -C, -I, -S, and -u are actually tog-
gles. A second specification of any of these options will negate the
first. Thus a user who has the environment variable TOP set to "-I"
may use the command "top -I" to see idle processes.
When top is running in "interactive mode", it reads commands from the
terminal and acts upon them accordingly. In this mode, the terminal is
put in "CBREAK", so that a character will be processed as soon as it is
typed. Almost always, a key will be pressed when top is between dis-
plays; that is, while it is waiting for 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 top 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 accord-
ingly. While typing this information in, the user's erase and kill
keys (as set up by the command stty) are recognized, and a newline ter-
minates the input. Note that a control-L (^L) always redraws the cur-
rent screen and a space forces an immediate update to the screen using
These commands are currently recognized:
h or ? Display a summary of the commands (help screen). Version infor-
mation is included in this display.
1 Toggle the display of per-cpu states.
C Toggle the use of color in the display.
c Display only processes whose commands match the specified
string. An empty string will display all processes. This com-
mand is not supported on all platforms.
d Change the number of displays to show (prompt for new number).
Remember that the next display counts as one, so typing d1 will
make top show one final display and then immediately exit.
f Toggle the display of the full command line.
H Toggle the display of threads on separate lines. By default, on
systems which support threading, each process is shown with a
count of the number of threads. This command shows each thread
on a separate line. This command is not supported on all plat-
i (or I) Toggle the display of idle processes.
k Send a signal ("kill" by default) to a list of processes. This
acts similarly to the command kill(1)).
M Sort display by memory usage. Shorthand for "o size".
m Change to a different process display mode. Some systems pro-
vide multiple display modes for the process display which shows
different information. This command toggles between the avail-
able modes. This command is not supported on all platforms.
N Sort by process id. Shorthand for "o pid".
n or # Change the number of processes to display (prompt for new num-
o Change the order in which the display is sorted. This command
is not available on all systems. The sort key names vary fron
system to system but usually include: "cpu", "res", "size",
"time". The default is cpu.
P Sort by CPU usage. Shorthand for "o cpu".
p Display only process with the specified pid (prompt for process
id). If the pid specified is simply "-1", then all processes
q Quit top.
r Change the priority (the "nice") of a list of processes. This
acts similarly to the command renice(8)).
s Change the number of seconds to delay between displays (prompt
for new number).
T Sort by CPU time. Shorthand for "o time".
U Toggle between displaying usernames and uids.
u Display only processes owned by a specific username (prompt for
username). If the username specified is simply "+", then pro-
cesses belonging to all users will be displayed.
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.
The top lines of the display show general information about the state
of the system. The first line shows (on some systems) the last process
id assigned to a process, the three load averages, the system uptime,
and the current time. The second line displays the total number of
processes followed by a breakdown of processes per state. Examples of
states common to Unix systems are sleeping, running, starting, stopped,
and zombie. The next line displays a percentage of time spent in each
of the processor states (typically user, nice, system, idle, and
iowait). These percentages show the processor activity during the time
since the last update. For multi-processor systems, this information
is a summation of time across all processors. The next line shows ker-
nel-related activity (not available on all systems). The numbers shown
on this line are per-second rates sampled since the last update. The
exact information displayed varies between systems, but some examples
are: context switches, interrupts, traps, forks, and page faults. The
last one or two lines show a summary of memory and swap activity.
These lines vary between systems.
The remainder of the screen displays information about individual pro-
cesses. This display is similar in spirit to ps(1) but it is not
exactly the same. The columns displayed by top will differ slightly
between operating systems. Generally, the following fields are dis-
PID The process id.
Username of the process's owner (if -u is specified, a UID col-
umn will be substituted for USERNAME).
THR The number of threads in the processes (this column may also be
PRI Current priority of the process.
NICE Nice amount in the range -20 to 20, as established by the use of
the command nice.
SIZE Total size of the process (text, data, and stack) given in kilo-
RES Resident memory: current amount of process memory that resides
in physical memory, given in kilobytes.
STATE Current state (typically one of "sleep", "run", "idl", "zomb",
TIME Number of system and user cpu seconds that the process has used.
CPU Percentage of available cpu time used by this process.
Name of the command that the process is currently running.
Top supports the use of ANSI color in its output. By default, color is
available but not used. The environment variable TOPCOLORS specifies
colors to use and conditions for which they should be used. At the
present time, only numbers in the summary display area can be colored.
In a future version it will be possible to highlight numbers in the
process display area as well. The environment variable is the only way
to specify color: there is no equivalent command line option. Note
that the environment variable TOPCOLOURS is also understood. The
British spelling takes precedence. The use of color only works on ter-
minals that understand and process ANSI color escape sequences.
The environment variable is a sequence of color specifications, sepa-
rated by colons. Each specification takes the form tag=min,max#code
where tag is the name of the value to check, min and max specify a
range for the value, and code is an ANSI color code. Multiple color
codes can be listed and separated with semi-colons. A missing min
implies the lowest possible value (usually 0) and a missing max implies
infinity. The comma must always be present. When specifying numbers for
load averages, they should be multiplied by 100. For example, the
specification 1min=500,1000#31 indicates that a 1 minute load average
between 5 and 10 should be displayed in red. Color attributes can be
combined. For example, the specification 5min=1000,#37;41 indicates
that a 5 minute load average higher than 10 should be displayed with
white characters on a red background. A special tag named header is
used to control the color of the header for process display. It should
be specified with no lower and upper limits, specifically header=,#
followed by the ANSI color code.
You can see a list of color codes recognized by this installation of
top with the -T option. This will also show the current set of tests
used for color highlighting, as specified in the environment.
TOP user-configurable defaults for options. TOPCOLORS color
As with ps(1), things can change while top is collecting information
for an update. The picture it gives is only a close approximation to
kill(1), ps(1), stty(1), mem(4), renice(8)
Copyright (C) 1984-2007 William LeFebvre. For additional licensing
information, see http://www.unixtop.org/license/
4th Berkeley Distribution December 28, 2016 TOP(1)