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 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.
- -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.
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 from 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 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.
- WCPU
- Weighted percentage of available cpu time used by this process.
- CPU
- Percentage of available cpu time used by this process.
- COMMAND
- 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 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.
TOP user-configurable defaults for options. TOPCOLORS color specification
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.
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/