TOP(1)TOP(1)NAMEtop - display and update information about the top cpu processes
SYNOPSIStop [ -Sbinu ] [ -dcount ] [ -stime ] [ number ]
DESCRIPTION
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.
OPTIONS-S 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.
-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.
-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.
-n Use "non-interactive" mode. This is indentical to "batch" mode.
-u 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.
-dcount
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. For intelligent terminals, no upper limit is
set. The default is 1 for dumb terminals.
-stime Set the delay between screen updates to time seconds. The
default delay between updates is 5 seconds.
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.
INTERACTIVE MODE
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.
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.
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.
n or # Change the number of processes to display (prompt for new num‐
ber).
s Change the number of seconds to delay between displays (prompt
for new number).
k Send a signal ("kill" by default) to a list of processes. This
acts similarly to the command kill(1)).
r Change the priority (the "nice") of a list of processes. This
acts similarly to the command renice(8)).
e Display a list of system errors (if any) generated by the last
kill or renice command.
THE DISPLAY
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, the three load averages, the current time, the number of
existing processes, the number of processes in each state (sleeping,
ABANDONED, 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 the amount of virtual and real memory in use
(with the amount of memory considered "active" in parentheses) and the
amount of free memory.
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. 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 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>").
NOTES
The "ABANDONED" state (known in the kernel as "SWAIT") was abandoned,
thus the name. A process should never end up in this state.
AUTHOR
William LeFebvre, Rice University graduate student
FILES
/dev/kmem kernel memory
/dev/mem physical memory
/etc/passwd used to map uid numbers to user names
/vmunix system image
BUGS
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.
SEE ALSOkill(1), ps(1), stty(1), mem(4), renice(8)4th Berkeley Distribution Local TOP(1)
