|TOP(1)||General Commands Manual||TOP(1)|
top — display and
update information about the top CPU processes
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
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:
^C’ and ‘
^\’) still have an effect. This is the default on a dumb terminal, or when the output is not a terminal.
topautomatically exits. For intelligent terminals, no upper limit is set. The default is 1 for dumb terminals.
topdisplays both active and idle processes.
topsupports cpu, size, res, time, pri, pid, and command.
topto -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.
topwill 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.
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
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 environment variable
-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.
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
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):
TERMby default) to process pid. This acts similarly to the command kill(1).
-oflag, as detailed above.
The top few lines of the display show general information about the state of the system, including 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.
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. The following fields are displayed:
onproc). On multiprocessor systems, this is followed by a slash and the CPU number on which the process is bound.
William LeFebvre, EECS Department, Northwestern University
As with ps(1),
top only provides snapshots of a constantly changing
|January 7, 2020||OpenBSD-current|