TOP(1)

TOP(1) | General Commands Manual | TOP(1)

# 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 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 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.
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.

# 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/

November 5, 2018 | 4th Berkeley Distribution