NAME
top - display and update information about the top cpu processes
SYNOPSIS
top [
-1CISTabcinqtuv ] [
-dcount ] [
-mmode ] [
-ofield ] [
-ppid ] [
-stime ] [
-Uusername ] [
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
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.
OPTIONS
- -1, --percpustates
- Display per-cpu states on a multi-processor machine.
- -C, --color
- Turn off the use of color in the display.
- -I, --idle-procs
- Do not display idle processes. By default, top displays
both active and idle processes.
- -S, --system-procs
- Show system processes in the display. Normally, system
processes such as the pager and the swapper are not shown. This option
makes them visible.
- -T, --tag-names
- List all available color tags and the current set of tests
used for color highlighting, then exit.
- -a, --all
- Show all processes for as long as possible. This is
shorthand for "-d all all". This option is especially handy in
batch mode.
- -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.
- -c, --full-commands
- Show the full command line for each process. Default is to
show just the command name. This option is not supported on all
platforms.
- -i, --interactive
- 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.
- -q, --quick
- 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.
- -t, --threads
- Show individual threads on separate lines. By default, on
systems 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.
- -u, --uids
- 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 execution
time. The uid numbers are displayed instead of the names.
- -v, --version
- Write version number information to stderr then exit
immediately. 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
automatically 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 information.
The value mode is a number indicating which mode to display. 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 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
-C,
-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.
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
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) are recognized, and a newline terminates the input. Note
that a control-L (^L) always redraws the current screen and a space forces an
immediate update to the screen using new data.
These commands are currently recognized:
- h or ?
- Display a summary of the commands (help screen). Version
information 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 command 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 platforms.
- 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
provide multiple display modes for the process display which shows
different information. This command toggles between the available 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
number).
- 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 are displayed.
- 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
processes belonging to all users will be displayed.
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.
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
kernel-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 processes.
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 displayed:
- PID
- The process id.
- USERNAME
- Username of the process's owner (if -u is specified,
a UID column will be substituted for USERNAME).
- THR
- The number of threads in the processes (this column may
also be labeled NLWP).
- 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
kilobytes.
- 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", or
"stop").
- TIME
- Number of system and user cpu seconds that the process has
used.
- CPU
- Percentage of available cpu time used by this process.
- COMMAND
- Name of the command that the process is currently
running.
COLOR
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 terminals that understand and process ANSI color escape sequences.
The environment variable is a sequence of color specifications, separated 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.
AUTHOR
William LeFebvre
ENVIRONMENT
TOP user-configurable defaults for options. TOPCOLORS color specification
BUGS
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 ALSO
kill(1), ps(1), stty(1), mem(4), renice(8)
COPYRIGHT
Copyright (C) 1984-2007 William LeFebvre. For additional licensing information,
see http://www.unixtop.org/license/