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TOP(1) Linux User's Manual TOP(1)
NAME
top - display Linux tasks
SYNOPSIS
<>
-hv | -bcHisS -d delay -n iterations -p pid [, pid ...]
The traditional switches '-' and whitespace are optional.
DESCRIPTION
The .ie 0 . br
program provides a dynamic real-time view of a running system. It can display system summary information as well as a
list of tasks currently being managed by the Linux kernel. The types of system summary information shown and the types,
order and size of information displayed for tasks are all user configurable and that configuration can be made persistent
across restarts.
The program provides a limited interactive interface for process manipulation as well as a much more extensive interface
for personal configuration -- encompassing every aspect of its operation. And while .ie 0 . br
is referred to throughout this document, you are free to name the program anything you wish. That new name, possibly an
alias, will then be reflected on top's display and used when reading and writing a configuration file.
OVERVIEW
Documentation
The remaining Table of Contents
1. COMMAND-LINE Options
2. FIELDS / Columns
a. DESCRIPTIONS of Fields
b. SELECTING and ORDERING Columns
3. INTERACTIVE Commands
a. GLOBAL Commands
b. SUMMARY Area Commands
c. TASK Area Commands
d. COLOR Mapping
4. ALTERNATE-DISPLAY Mode
a. WINDOWS Overview
b. COMMANDS for Windows
5. FILES
a. SYSTEM Configuration File
b. PERSONAL Configuration File
6. STUPID TRICKS Sampler
a. Kernel Magic
b. Bouncing Windows
c. The Big Bird Window
7. BUGS, 8. HISTORY Former top, 9. AUTHOR, 10. SEE ALSO
Operation
When operating top, the two most important keys are help ('h' or '?') and quit ('q') key. Alternatively, you could sim-
ply use the traditional interrupt key ('^C') when you're done.
When you start top for the first time, you'll be presented with the traditional screen elements: 1) Summary Area; 2) Mes-
sage/Prompt Line; 3) Columns Header; 4) Task Area. There will, however, be some differences when compared to the former
top.
Highlighting
Summary_Area: There is no highlighting for load/uptime and only values are highlighted for other elements.
Task_Area: Tasks running (or ready to run) will be highlighted, and bold is only one way of emphasizing such pro-
cesses.
Content/Labels
Summary_Area: The program name is shown, perhaps a symlink or alias. The Cpu(s) state label hints at other possibili-
ties. The memory stats use a lower case 'k'.
Columns_Header: Will show a new field and some changed labels. More new fields will be found as you customize your
top.
Note: the width of top's display will be limited to 512 positions. Displaying all fields requires a minimum of 160 char-
acters. The remaining width could be used for the 'Command' column.
Startup Defaults
The following startup defaults assume no configuration file, thus no user customizations. Even so, items shown with an
asterisk ('*') could be overridden through the command-line.
Global_defaults
'A' - Alt display Off (full-screen)
* 'd' - Delay time 3.0 seconds
'I' - Irix mode On (no, 'solaris' smp)
* 'p' - PID monitoring Off
* 's' - Secure mode Off (unsecured)
'B' - Bold disable Off
Summary_Area_defaults
'l' - Load Avg/Uptime On (thus program name)
't' - Task/Cpu states On (1+1 lines, see '1')
'm' - Mem/Swap usage On (2 lines worth)
'1' - Single Cpu On (thus 1 line if smp)
Task_Area_defaults
'b' - Bold hilite On (not 'reverse')
* 'c' - Command line Off (name, not cmdline)
* 'H' - Threads Off (show all threads)
* 'i' - Idle tasks On (show all tasks)
'R' - Reverse sort On (pids high-to-low)
* 'S' - Cumulative time Off (no, dead children)
'x' - Column hilite Off (no, sort field)
'y' - Row hilite On (yes, running tasks)
'z' - color/mono Off (no, colors)
1. COMMAND-LINE Options
The command-line syntax for top consists of:
-hv | -bcHisS -d delay -n iterations -p pid [,pid...]
The typically mandatory switches ('-') and even whitespace are completely optional.
-b : Batch mode operation
Starts top in 'Batch mode', which could be useful for sending output from top to other programs or to a file. In
this mode, top will not accept input and runs until the iterations limit you've set with the '-n' command-line
option or until killed.
-c : Command line/Program name toggle
Starts top with the last remembered 'c' state reversed. Thus, if top was displaying command lines, now that field
will show program names, and visa versa. See the 'c' interactive command for additional information.
-d : Delay time interval as: -d ss.tt (seconds.tenths)
Specifies the delay between screen updates, and overrides the corresponding value in one's personal configuration
file or the startup default. Later this can be changed with the 'd' or 's' interactive commands.
Fractional seconds are honored, but a negative number is not allowed. In all cases, however, such changes are pro-
hibited if top is running in 'Secure mode', except for root (unless the 's' command-line option was used). For
additional information on 'Secure mode' see topic 5a. SYSTEM Configuration File.
-h : Help
Show library version and the usage prompt, then quit.
-H : Threads toggle
Starts top with the last remembered 'H' state reversed. When this toggle is On, all individual threads will be dis-
played. Otherwise, top displays a summation of all threads in a process.
-i : Idle Processes toggle
Starts top with the last remembered 'i' state reversed. When this toggle is Off, tasks that are idled or zombied
will not be displayed.
-n : Number of iterations limit as: -n number
Specifies the maximum number of iterations, or frames, top should produce before ending.
-u : Monitor by user as: -u somebody
Monitor only processes with an effective UID or user name matching that given.
-U : Monitor by user as: -U somebody
Monitor only processes with a UID or user name matching that given. This matches real, effective, saved, and
filesystem UIDs.
-p : Monitor PIDs as: -pN1 -pN2 ... or -pN1, N2 [,...]
Monitor only processes with specified process IDs. This option can be given up to 20 times, or you can provide a
comma delimited list with up to 20 pids. Co-mingling both approaches is permitted.
This is a command-line option only. And should you wish to return to normal operation, it is not necessary to quit
and and restart top -- just issue the '=' interactive command.
-s : Secure mode operation
Starts top with secure mode forced, even for root. This mode is far better controlled through the system configura-
tion file (see topic 5. FILES).
-S : Cumulative time mode toggle
Starts top with the last remembered 'S' state reversed. When 'Cumulative mode' is On, each process is listed with
the cpu time that it and its dead children have used. See the 'S' interactive command for additional information
regarding this mode.
-v : Version
Show library version and the usage prompt, then quit.
2. FIELDS / Columns
2a. DESCRIPTIONS of Fields
Listed below are top's available fields. They are always associated with the letter shown, regardless of the position
you may have established for them with the 'o' (Order fields) interactive command.
Any field is selectable as the sort field, and you control whether they are sorted high-to-low or low-to-high. For addi-
tional information on sort provisions see topic 3c. TASK Area Commands.
a: PID -- Process Id
The task's unique process ID, which periodically wraps, though never restarting at zero.
b: PPID -- Parent Process Pid
The process ID of a task's parent.
c: RUSER -- Real User Name
The real user name of the task's owner.
d: UID -- User Id
The effective user ID of the task's owner.
e: USER -- User Name
The effective user name of the task's owner.
f: GROUP -- Group Name
The effective group name of the task's owner.
g: TTY -- Controlling Tty
The name of the controlling terminal. This is usually the device (serial port, pty, etc.) from which the process was
started, and which it uses for input or output. However, a task need not be associated with a terminal, in which case
you'll see '?' displayed.
h: PR -- Priority
The priority of the task.
i: NI -- Nice value
The nice value of the task. A negative nice value means higher priority, whereas a positive nice value means lower
priority. Zero in this field simply means priority will not be adjusted in determining a task's dispatchability.
j: P -- Last used CPU (SMP)
A number representing the last used processor. In a true SMP environment this will likely change frequently since the
kernel intentionally uses weak affinity. Also, the very act of running top may break this weak affinity and cause
more processes to change CPUs more often (because of the extra demand for cpu time).
k: %CPU -- CPU usage
The task's share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time.
In a true SMP environment, if 'Irix mode' is Off, top will operate in 'Solaris mode' where a task's cpu usage will be
divided by the total number of CPUs. You toggle 'Irix/Solaris' modes with the 'I' interactive command.
l: TIME -- CPU Time
Total CPU time the task has used since it started. When 'Cumulative mode' is On, each process is listed with the cpu
time that it and its dead children has used. You toggle 'Cumulative mode' with 'S', which is a command-line option
and an interactive command. See the 'S' interactive command for additional information regarding this mode.
m: TIME+ -- CPU Time, hundredths
The same as 'TIME', but reflecting more granularity through hundredths of a second.
n: %MEM -- Memory usage (RES)
A task's currently used share of available physical memory.
o: VIRT -- Virtual Image (kb)
The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that
have been swapped out. (Note: you can define the STATSIZE=1 environment variable and the VIRT will be calculated from
the /proc/#/state VmSize field.)
VIRT = SWAP + RES.
p: SWAP -- Swapped size (kb)
The swapped out portion of a task's total virtual memory image.
q: RES -- Resident size (kb)
The non-swapped physical memory a task has used.
RES = CODE + DATA.
r: CODE -- Code size (kb)
The amount of physical memory devoted to executable code, also known as the 'text resident set' size or TRS.
s: DATA -- Data+Stack size (kb)
The amount of physical memory devoted to other than executable code, also known as the 'data resident set' size or
DRS.
t: SHR -- Shared Mem size (kb)
The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other
processes.
u: nFLT -- Page Fault count
The number of major page faults that have occurred for a task. A page fault occurs when a process attempts to read
from or write to a virtual page that is not currently present in its address space. A major page fault is when disk
access is involved in making that page available.
v: nDRT -- Dirty Pages count
The number of pages that have been modified since they were last written to disk. Dirty pages must be written to disk
before the corresponding physical memory location can be used for some other virtual page.
w: S -- Process Status
The status of the task which can be one of:
'D' = uninterruptible sleep
'R' = running
'S' = sleeping
'T' = traced or stopped
'Z' = zombie
Tasks shown as running should be more properly thought of as 'ready to run' -- their task_struct is simply repre-
sented on the Linux run-queue. Even without a true SMP machine, you may see numerous tasks in this state depending on
top's delay interval and nice value.
x: Command -- Command line or Program name
Display the command line used to start a task or the name of the associated program. You toggle between command line
and name with 'c', which is both a command-line option and an interactive command.
When you've chosen to display command lines, processes without a command line (like kernel threads) will be shown with
only the program name in parentheses, as in this example:
( mdrecoveryd )
Either form of display is subject to potential truncation if it's too long to fit in this field's current width. That
width depends upon other fields selected, their order and the current screen width.
Note: The 'Command' field/column is unique, in that it is not fixed-width. When displayed, this column will be allo-
cated all remaining screen width (up to the maximum 512 characters) to provide for the potential growth of program
names into command lines.
y: WCHAN -- Sleeping in Function
Depending on the availability of the kernel link map ('System.map'), this field will show the name or the address of
the kernel function in which the task is currently sleeping. Running tasks will display a dash ('-') in this column.
Note: By displaying this field, top's own working set will be increased by over 700Kb. Your only means of reducing
that overhead will be to stop and restart top.
z: Flags -- Task Flags
This column represents the task's current scheduling flags which are expressed in hexadecimal notation and with zeros
suppressed. These flags are officially documented in <linux/sched.h>. Less formal documentation can also be found on
the 'Fields select' and 'Order fields' screens.
2b. SELECTING and ORDERING Columns
After pressing the interactive commands 'f' (Fields select) or 'o' (Order fields) you will be shown a screen containing
the current fields string followed by names and descriptions for all fields.
Here is a sample fields string from one of top's four windows/field groups and an explanation of the conventions used:
- Sample fields string:
ANOPQRSTUVXbcdefgjlmyzWHIK
- The order of displayed fields corresponds to the order of the letters in that string.
- If the letter is upper case the corresponding field itself will then be shown as part of the task display (screen
width permitting). This will also be indicated by a leading asterisk ('*'), as in this excerpt:
...
* K: %CPU = CPU usage
l: TIME = CPU Time
m: TIME+ = CPU Time, hundredths
* N: %MEM = Memory usage (RES)
* O: VIRT = Virtual Image (kb)
...
Fields select screen -- the 'f' interactive command
You toggle the display of a field by simply pressing the corresponding letter.
Order fields screen -- the 'o' interactive command
You move a field to the left by pressing the corresponding upper case letter and to the right with the lower case let-
ter.
2c. SUMMARY Area Fields
The summary area fields describing CPU statistics are abbreviated. They provide information about times spent in:
us = user mode
sy = system mode
ni = low priority user mode (nice)
id = idle task
wa = I/O waiting
hi = servicing IRQs
si = servicing soft IRQs
st = steal (time given to other DomU instances)
3. INTERACTIVE Commands
Listed below is a brief index of commands within categories. Some commands appear more than once -- their meaning or
scope may vary depending on the context in which they are issued.
3a. GLOBAL_Commands
<Ret/Sp> ?, =, A, B, d, G, h, I, k, q, r, s, W, Z
3b. SUMMARY_Area_Commands
l, m, t, 1
3c. TASK_Area_Commands
Appearance: b, x, y, z
Content: c, f, H, o, S, u
Size: #, i, n
Sorting: <, >, F, O, R
3d. COLOR_Mapping
<Ret>, a, B, b, H, M, q, S, T, w, z, 0 - 7
4b. COMMANDS_for_Windows
-, _, =, +, A, a, G, g, w
3a. GLOBAL Commands
The global interactive commands are always available in both full-screen mode and alternate-display mode. However, some
of these interactive commands are not available when running in 'Secure mode'.
If you wish to know in advance whether or not your top has been secured, simply ask for help and view the system summary
on the second line.
<Enter> or <Space> :Refresh_Display
These commands do nothing, they are simply ignored. However, they will awaken top and following receipt of any
input the entire display will be repainted.
Use either of these keys if you have a large delay interval and wish to see current status,
'?' or 'h' :Help
There are two help levels available. The first will provide a reminder of all the basic interactive commands. If
top is secured, that screen will be abbreviated.
Typing 'h' or '?' on that help screen will take you to help for those interactive commands applicable to alter-
nate-display mode.
'=' :Exit_Task_Limits
Removes restrictions on which tasks are shown. This command will reverse any 'i' (idle tasks) and 'n' (max tasks)
commands that might be active. It also provides for an 'exit' from PID monitoring. See the '-p' command-line
option for a discussion of PID monitoring.
When operating in alternate-display mode this command has a slightly broader meaning.
'A' :Alternate_Display_Mode_toggle
This command will switch between full-screen mode and alternate-display mode. See topic 4. ALTERNATE-DISPLAY Mode
and the 'G' interactive command for insight into 'current' windows and field groups.
'B' :Bold_Disable/Enable_toggle
This command will influence use of the 'bold' terminfo capability and alters both the summary area and task area
for the 'current' window. While it is intended primarily for use with dumb terminals, it can be applied anytime.
Note: When this toggle is On and top is operating in monochrome mode, the entire display will appear as normal
text. Thus, unless the 'x' and/or 'y' toggles are using reverse for emphasis, there will be no visual confirma-
tion that they are even on.
* 'd' or 's' :Change_Delay_Time_interval
You will be prompted to enter the delay time, in seconds, between display updates.
Fractional seconds are honored, but a negative number is not allowed. Entering 0 causes (nearly) continuous
updates, with an unsatisfactory display as the system and tty driver try to keep up with top's demands. The delay
value is inversely proportional to system loading, so set it with care.
If at any time you wish to know the current delay time, simply ask for help and view the system summary on the
second line.
'G' :Choose_Another_Window/Field_Group
You will be prompted to enter a number between 1 and 4 designating the window/field group which should be made the
'current' window. You will soon grow comfortable with these 4 windows, especially after experimenting with alter-
nate-display mode.
'I' :Irix/Solaris_Mode_toggle
When operating in 'Solaris mode' ('I' toggled Off), a task's cpu usage will be divided by the total number of
CPUs. After issuing this command, you'll be informed of the new state of this toggle.
'u' :select a user
You will be prompted for a UID or username. Only processes belonging to the selected user will be displayed. This
option matches on the effective UID.
'U' :select a user
You will be prompted for a UID or username. Only processes belonging to the selected user will be displayed. This
option matches on the real, effective, saved, and filesystem UID.
* 'k' :Kill_a_task
You will be prompted for a PID and then the signal to send. The default signal, as reflected in the prompt, is
SIGTERM. However, you can send any signal, via number or name.
If you wish to abort the kill process, do one of the following depending on your progress:
1) at the pid prompt, just press <Enter>
2) at the signal prompt, type 0
'q' :Quit
* 'r' :Renice_a_Task
You will be prompted for a PID and then the value to nice it to. Entering a positive value will cause a process
to lose priority. Conversely, a negative value will cause a process to be viewed more favorably by the kernel.
'W' :Write_the_Configuration_File
This will save all of your options and toggles plus the current display mode and delay time. By issuing this com-
mand just before quitting top, you will be able restart later in exactly that same state.
'Z' :Change_Color_Mapping
This key will take you to a separate screen where you can change the colors for the 'current' window, or for all
windows. For details regarding this interactive command see topic 3d. COLOR Mapping.
* The commands shown with an asterisk ('*') are not available in 'Secure mode', nor will they be shown on the level-1
help screen.
3b. SUMMARY Area Commands
The summary area interactive commands are always available in both full-screen mode and alternate-display mode. They
affect the beginning lines of your display and will determine the position of messages and prompts.
These commands always impact just the 'current' window/field group. See topic 4. ALTERNATE-DISPLAY Mode and the 'G'
interactive command for insight into 'current' windows and field groups.
'l' :Toggle_Load_Average/Uptime -- On/Off
This is also the line containing the program name (possibly an alias) when operating in full-screen mode or the
'current' window name when operating in alternate-display mode.
'm' :Toggle_Memory/Swap_Usage -- On/Off
This command affects two summary area lines.
't' :Toggle_Task/Cpu_States -- On/Off
This command affects from 2 to many summary area lines, depending on the state of the '1' toggle and whether or
not top is running under true SMP.
'1' :Toggle_Single/Separate_Cpu_States -- On/Off
This command affects how the 't' command's Cpu States portion is shown. Although this toggle exists primarily to
serve massively-parallel SMP machines, it is not restricted to solely SMP environments.
When you see 'Cpu(s):' in the summary area, the '1' toggle is On and all cpu information is gathered in a single
line. Otherwise, each cpu is displayed separately as: 'Cpu0, Cpu1, ...'
Note: If the entire summary area has been toggled Off for any window, you would be left with just the message line. In
that way, you will have maximized available task rows but (temporarily) sacrificed the program name in full-screen mode
or the 'current' window name when in alternate-display mode.
3c. TASK Area Commands
The task area interactive commands are always available in full-screen mode.
The task area interactive commands are never available in alternate-display mode if the 'current' window's task display
has been toggled Off (see topic 4. ALTERNATE-DISPLAY Mode).
APPEARANCE of task window
The following commands will also be influenced by the state of the global 'B' (bold disable) toggle.
'b' :Bold/Reverse_toggle
This command will impact how the 'x' and 'y' toggles are displayed. Further, it will only be available when at
least one of those toggles is On.
'x' :Column_Highlight_toggle
Changes highlighting for the current sort field. You probably don't need a constant visual reminder of the sort
field and top hopes that you always run with 'column highlight' Off, due to the cost in path-length.
If you forget which field is being sorted this command can serve as a quick visual reminder.
'y' :Row_Highlight_toggle
Changes highlighting for "running" tasks. For additional insight into this task state, see topic 2a. DESCRIPTIONS
of Fields, Process Status.
Use of this provision provides important insight into your system's health. The only costs will be a few addi-
tional tty escape sequences.
'z' :Color/Monochrome_toggle
Switches the 'current' window between your last used color scheme and the older form of black-on-white or white-
on-black. This command will alter both the summary area and task area but does not affect the state of the 'x',
'y' or 'b' toggles.
CONTENT of task window
'c' :Command_Line/Program_Name_toggle
This command will be honored whether or not the 'Command' column is currently visible. Later, should that field
come into view, the change you applied will be seen.
'f' and 'o' :Fields_select or Order_fields
These keys display separate screens where you can change which fields are displayed and their order. For addi-
tional information on these interactive commands see topic 2b. SELECTING and ORDERING Columns.
'H' :Threads_toggle
When this toggle is On, all individual threads will be displayed. Otherwise, top displays a summation of all
threads in a process.
'S' :Cumulative_Time_Mode_toggle
When 'Cumulative mode' is On, each process is listed with the cpu time that it and its dead children have used.
When Off, programs that fork into many separate tasks will appear less demanding. For programs like 'init' or a
shell this is appropriate but for others, like compilers, perhaps not. Experiment with two task windows sharing
the same sort field but with different 'S' states and see which representation you prefer.
After issuing this command, you'll be informed of the new state of this toggle. If you wish to know in advance
whether or not 'Cumulative mode' is in effect, simply ask for help and view the window summary on the second line.
'u' :Show_Specific_User_Only
You will be prompted to enter the name of the user to display. Thereafter, in that task window only matching User
ID's will be shown, or possibly no tasks will be shown.
Later, if you wish to monitor all tasks again, re-issue this command but just press <Enter> at the prompt, without
providing a name.
SIZE of task window
'i' :Idle_Processes_toggle
Displays all tasks or just active tasks. When this toggle is Off, idled or zombied processes will not be dis-
played.
If this command is applied to the last task display when in alternate-display mode, then it will not affect the
window's size, as all prior task displays will have already been painted.
'n' or '#' :Set_Maximum_Tasks
You will be prompted to enter the number of tasks to display. The lessor of your number and available screen rows
will be used.
When used in alternate-display mode, this is the command that gives you precise control over the size of each cur-
rently visible task display, except for the very last. It will not affect the last window's size, as all prior
task displays will have already been painted.
Note: If you wish to increase the size of the last visible task display when in alternate-display mode, simply
decrease the size of the task display(s) above it.
SORTING of task window
For compatibility, this top supports most of the former top sort keys. Since this is primarily a service to former top
users, these commands do not appear on any help screen.
command sorted field supported
A start time (non-display) No
M %MEM Yes
N PID Yes
P %CPU Yes
T TIME+ Yes
Before using any of the following sort provisions, top suggests that you temporarily turn on column highlighting using
the 'x' interactive command. That will help ensure that the actual sort environment matches your intent.
The following interactive commands will only be honored when the current sort field is visible. The sort field might
not be visible because:
1) there is insufficient Screen Width
2) the 'f' interactive command turned it Off
'<' :Move_Sort_Field_Left
Moves the sort column to the left unless the current sort field is the first field being displayed.
'>' :Move_Sort_Field_Right
Moves the sort column to the right unless the current sort field is the last field being displayed.
The following interactive commands will always be honored whether or not the current sort field is visible.
'F' or 'O' :Select_Sort_Field
These keys display a separate screen where you can change which field is used as the sort column.
If a field is selected which was not previously being displayed, it will be forced On when you return to the top
display. However, depending upon your screen width and the order of your fields, this sort field may not be dis-
playable.
This interactive command can be a convenient way to simply verify the current sort field, when running top with
column highlighting turned Off.
'R' :Reverse/Normal_Sort_Field_toggle
Using this interactive command you can alternate between high-to-low and low-to-high sorts.
Note: Field sorting uses internal values, not those in column display. Thus, the TTY and WCHAN fields will violate
strict ASCII collating sequence.
3d. COLOR Mapping
When you issue the 'Z' interactive command, you will be presented with a separate screen. That screen can be used to
change the colors in just the 'current' window or in all four windows before returning to the top display.
Available interactive commands
4 upper case letters to select a target
8 numbers to select a color
normal toggles available
'B' :bold disable/enable
'b' :running tasks "bold"/reverse
'z' :color/mono
other commands available
'a'/'w' :apply, then go to next/prior
<Enter> :apply and exit
'q' :abandon current changes and exit
If your use 'a' or 'w' to cycle the targeted window, you will have applied the color scheme that was displayed when you
left that window. You can, of course, easily return to any window and reapply different colors or turn colors Off com-
pletely with the 'z' toggle.
The Color Mapping screen can also be used to change the 'current' window/field group in either full-screen mode or alter-
nate-display mode. Whatever was targeted when 'q' or <Enter> was pressed will be made current as you return to the top
display.
4. ALTERNATE-DISPLAY Mode
4a. WINDOWS Overview
Field Groups/Windows:
In full-screen mode there is a single window represented by the entire screen. That single window can still be
changed to display 1 of 4 different field groups (see the 'G' interactive command, repeated below). Each of the 4
field groups has a unique separately configurable summary area and its own configurable task area.
In alternate-display mode, those 4 underlying field groups can now be made visible simultaneously, or can be
turned Off individually at your command.
The summary area will always exist, even if it's only the message line. At any given time only one summary area
can be displayed. However, depending on your commands, there could be from zero to four separate task displays
currently showing on the screen.
Current Window:
The 'current' window is the window associated with the summary area and the window to which task related commands
are always directed. Since in alternate-display mode you can toggle the task display Off, some commands might be
restricted for the 'current' window.
A further complication arises when you have toggled the first summary area line Off. With the loss of the window
name (the 'l' toggled line), you'll not easily know what window is the 'current' window.
4b. COMMANDS for Windows
'-' and '_' :Show/Hide_Window(s)_toggles
The '-' key turns the 'current' window's task display On and Off. When On, that task area will show a minimum of
the columns header you've established with the 'f' and 'o' commands. It will also reflect any other task area
options/toggles you've applied yielding zero or more tasks.
The '_' key does the same for all task displays. In other words, it switches between the currently visible task
display(s) and any task display(s) you had toggled Off. If all 4 task displays are currently visible, this inter-
active command will leave the summary area as the only display element.
* '=' and '+' :Equalize_(re-balance)_Window(s)
The '=' key forces the 'current' window's task display to be visible. It also reverses any 'i' (idle tasks) and
'n' (max tasks) commands that might be active.
The '+' key does the same for all windows. The four task displays will reappear, evenly balanced. They will also
have retained any customizations you had previously applied, except for the 'i' (idle tasks) and 'n' (max tasks)
commands.
* 'A' :Alternate_Display_Mode_toggle
This command will switch between full-screen mode and alternate-display mode.
The first time you issue this command, all four task displays will be shown. Thereafter when you switch modes,
you will see only the task display(s) you've chosen to make visible.
* 'a' and 'w' :Next_Window_Forward/Backward
This will change the 'current' window, which in turn changes the window to which commands are directed. These
keys act in a circular fashion so you can reach any desired 'current' window using either key.
Assuming the window name is visible (you have not toggled 'l' Off), whenever the 'current' window name loses its
emphasis/color, that's a reminder the task display is Off and many commands will be restricted.
* 'G' :Choose_Another_Window/Field_Group
You will be prompted to enter a number between 1 and 4 designating the window/field group which should be made the
'current' window.
In full-screen mode, this command is necessary to alter the 'current' window. In alternate-display mode, it is
simply a less convenient alternative to the 'a' and 'w' commands.
'g' :Change_Window/Field_Group_Name
You will be prompted for a new name to be applied to the 'current' window. It does not require that the window
name be visible (the 'l' toggle to be On).
* The interactive commands shown with an asterisk ('*') have use beyond alternate-display mode.
'=', 'A', 'G' are always available
'a', 'w' act the same when color mapping
5. FILES
5a. SYSTEM Configuration File
The presence of this file will influence which version of the 'help' screen is shown to an ordinary user. More impor-
tantly, it will limit what ordinary users are allowed to do when top is running. They will not be able to issue the fol-
lowing commands.
k Kill a task
r Renice a task
d or s Change delay/sleep interval
The system configuration file is not created by top. Rather, you create this file manually and place it in the /etc
directory. Its name must be 'toprc' and must have no leading '.' (period). It must have only two lines.
Here is an example of the contents of /etc/toprc:
s # line 1: 'secure' mode switch
5.0 # line 2: 'delay' interval in seconds
5b. PERSONAL Configuration File
This file is written as '$HOME/.your-name-4-top' + 'rc'. Use the 'W' interactive command to create it or update it.
Here is the general layout:
global # line 1: the program name/alias notation
" # line 2: id,altscr,irixps,delay,curwin
per ea # line a: winname,fieldscur
window # line b: winflags,sortindx,maxtasks
" # line c: summclr,msgsclr,headclr,taskclr
If the $HOME variable is not present, top will try to write the personal configuration file to the current directory,
subject to permissions.
6. STUPID TRICKS Sampler
Many of these 'tricks' work best when you give top a scheduling boost. So plan on starting him with a nice value of -10,
assuming you've got the authority.
6a. Kernel Magic
For these stupid tricks, top needs full-screen mode.
-*- The user interface, through prompts and help, intentionally implies that the delay interval is limited to tenths of
a second. However, you're free to set any desired delay. If you want to see Linux at his scheduling best, try a
delay of .09 seconds or less.
For this experiment, under x-windows open an xterm and maximize it. Then do the following:
. provide a scheduling boost and tiny delay via:
nice -n -10 top -d.09
. keep sorted column highlighting Off to minimize
path length
. turn On reverse row highlighting for emphasis
. try various sort columns (TIME/MEM work well),
and normal or reverse sorts to bring the most
active processes into view
What you'll see is a very busy Linux doing what he's always done for you, but there was no program available to
illustrate this.
-*- Under an xterm using 'white-on-black' colors, try setting top's task color to black and be sure that task highlight-
ing is set to bold, not reverse. Then set the delay interval to around .3 seconds.
After bringing the most active processes into view, what you'll see are the ghostly images of just the currently
running tasks.
-*- Delete the existing rcfile, or create a new symlink. Start this new version then type 'T' (a secret key, see topic
3c. TASK Area Commands, Sorting) followed by 'W' and 'q'. Finally, restart the program with -d0 (zero delay).
Your display will be refreshed at three times the rate of the former top, a 300% speed advantage. As top climbs the
TIME ladder, be as patient as you can while speculating on whether or not top will ever reach the top.
6b. Bouncing Windows
For these stupid tricks, top needs alternate-display mode.
-*- With 3 or 4 task displays visible, pick any window other than the last and turn idle processes Off. Depending on
where you applied 'i', sometimes several task displays are bouncing and sometimes it's like an accordion, as top
tries his best to allocate space.
-*- Set each window's summary lines differently: one with no memory; another with no states; maybe one with nothing at
all, just the message line. Then hold down 'a' or 'w' and watch a variation on bouncing windows -- hopping win-
dows.
-*- Display all 4 windows and for each, in turn, set idle processes to Off. You've just entered the "extreme bounce"
zone.
6c. The Big Bird Window
This stupid trick also requires alternate-display mode.
-*- Display all 4 windows and make sure that 1:Def is the 'current' window. Then, keep increasing window size until the
all the other task displays are "pushed out of the nest".
When they've all been displaced, toggle between all visible/invisible windows. Then ponder this:
is top fibbing or telling honestly your imposed truth?
7. BUGS
Send bug reports to:
Albert D. Cahalan, <albertATusers.net>
The top command calculates Cpu(s) by looking at the change in CPU time values between samples. When you first run it, it
has no previous sample to compare to, so these initial values are the percentages since boot. It means you need at least
two loops or you have to ignore summary output from the first loop. This is problem for example for batch mode. There is
a possible workaround if you define the CPULOOP=1 environment variable. The top command will be run one extra hidden loop
for CPU data before standard output.
8. HISTORY Former top
The original top was written by Roger Binns, based on Branko Lankester's <lankesteATfwi.nl> ps program.
Robert Nation <nationATrocket.com> adapted it for the proc file system.
Helmut Geyer <Helmut.GeyerATiwr.de> added support for configurable fields.
Plus many other individuals contributed over the years.
9. AUTHOR
This entirely new and enhanced replacement was written by:
Jim / James C. Warner, <warnerjcATworldnet.net>
With invaluable help from:
Albert D. Cahalan, <albertATusers.net>
Craig Small, <csmallATsmall.au>
10. SEE ALSO
free(1), ps(1), uptime(1), atop(1), slabtop(1), vmstat(8), w(1).
Linux September 2002 TOP(1)
