top - display and update information about the top CPU processes
top [-biInqSu] [-d count] [-o field] [-s time] [-U username]
[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 capabilities
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 redirected
to a file, it acts as if it were being run on a dumb terminal.
The options are as follows:
-b 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.
-d 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 to be shown before top
automatically
exits. For intelligent terminals, no upper limit is
set. The
default is 1 for dumb terminals.
-i 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.
-I Do not display idle processes. By default, top displays both active
and idle processes.
-n Use non-interactive mode. This is identical to
batch mode.
-o field
Sort the process display area using the specified
field as the
primary key. The field name is the name of the column as seen in
the output, but in lower case. The OpenBSD version
of top supports
cpu, size, res, time, and pri.
-q Renice top 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.
-s time
Set the delay between screen updates to time seconds. The value
may be fractional, to permit delays of less than 1
second. The
default delay between updates is 5 seconds.
-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.
-u Do not take the time to map UID numbers to usernames. Normally,
top 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.
-U username
Show only those processes owned by username. This
option currently
only accepts usernames and will not understand UID numbers.
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, infinity.
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 environment
variable TOP.
The options -I, -S, and -u are actually toggles. 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
displays; 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 accordingly.
While typing
this information in, the user's erase and kill keys (as set
up by the
command stty(1)) are recognized, and a newline terminates
the input.
These commands are currently recognized (^L refers to control-L):
^L Redraw the screen.
h or ? Display a summary of the commands (help screen).
q Quit top.
The following commands may not be available with overstrike
terminals:
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.
e Display a list of system errors (if any) generated
by the last
kill or renice command.
i or I Toggle the display of idle processes.
k Send a signal (TERM by default) to a list of processes. This
acts similarly to the command kill(1).
n or # Change the number of processes to display (prompt
for new number).
o Change the sorting order of the processes (prompt
for order).
Values are the same as for the -o flag, as detailed
above.
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).
S Toggle the display of system processes.
u Display only processes owned by a specific username
(prompt for
username). If the username specified is simply
``+'', then processes
belonging to all users will be displayed.
The top few lines of the display show general information
about the state
of the system, including the three load average numbers, the
current
time, the number of existing processes, the number of processes in each
state (sleeping, running, starting, zombies, and stopped),
and a percentage
of time spent in each of the processor states (user,
nice, system,
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.
The remainder of the screen displays information about individual processes.
This display is similar in spirit to ps(1) but it
is not exactly
the same. PID is the process ID, USERNAME is the name of
the process's
owner (if -u is specified, a UID column will be substituted
for USERNAME),
PRI is the current priority of the process, NICE is
the nice
amount (in the range -20 to 20), SIZE is the total size of
the process
(text, data, and stack), RES is the current amount of resident memory
(both SIZE and RES are given in kilobytes), STATE is the
current state
(one of sleep, WAIT, run, idl, zomb, or stop), TIME is the
number of system
and user CPU seconds that the process has used, WCPU,
when displayed,
is the weighted CPU percentage (this is the same value that
ps(1) displays
as CPU), CPU is the raw percentage and is the field
that is sorted
to determine the order of the processes, and COMMAND is the
name of the
command that the process is currently running (if the process is swapped
out, this column is marked <swapped>).
The ABANDONED state (known in the kernel as SWAIT) was abandoned, thus
the name. A process should never end up in this state.
TOP User-configurable defaults for options.
/dev/kmem kernel memory
/dev/mem physical memory
/bsd kernel image
kill(1), ps(1), stty(1), systat(1), mem(4), renice(8)
William LeFebvre, EECS Department, Northwestern University
The command name for swapped processes should be tracked
down, but this
would make the program run slower.
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 reality.
OpenBSD 3.6 August 14, 1997
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