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top(1) - phpMan
TOP(1) User Commands TOP(1)
NAME
top - display Linux processes
SYNOPSIS
top -hv|-bcHiOSs -d secs -n max -u|U user -p pid -o fld -w [cols]
The traditional switches '-' and whitespace are optional.
DESCRIPTION
The top program provides a dynamic real-time view of a running system. It can display
system summary information as well as a list of processes or threads currently being man‐
aged by the Linux kernel. The types of system summary information shown and the types,
order and size of information displayed for processes 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 top 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. SUMMARY Display
a. UPTIME and LOAD Averages
b. TASK and CPU States
c. MEMORY Usage
3. FIELDS / Columns Display
a. DESCRIPTIONS of Fields
b. MANAGING Fields
4. INTERACTIVE Commands
a. GLOBAL Commands
b. SUMMARY AREA Commands
c. TASK AREA Commands
1. Appearance
2. Content
3. Size
4. Sorting
d. COLOR Mapping
5. ALTERNATE-DISPLAY Provisions
a. WINDOWS Overview
b. COMMANDS for Windows
c. SCROLLING a Window
d. SEARCHING in a Window
e. FILTERING in a Window
6. FILES
a. SYSTEM Configuration File
b. PERSONAL Configuration File
c. ADDING INSPECT Entries
7. STUPID TRICKS Sampler
a. Kernel Magic
b. Bouncing Windows
c. The Big Bird Window
d. The Ol' Switcheroo
8. BUGS, 9. HISTORY Former top, 10. AUTHOR, 11. SEE Also
Operation
When operating top, the two most important keys are the help ('h' or '?') key and quit
('q') key. Alternatively, you could simply use the traditional interrupt key ('^C') when
you're done.
When started for the first time, you'll be presented with these traditional elements on
the main top screen: 1) Summary Area; 2) Fields/Columns Header; 3) Task Area. Each of
these will be explored in the sections that follow. There is also an Input/Message line
between the Summary Area and Columns Header which needs no further explanation.
The main top screen is generally quite adaptive to changes in terminal dimensions under X-
Windows. Other top screens may be less so, especially those with static text. It ulti‐
mately depends, however, on your particular window manager and terminal emulator. There
may be occasions when their view of terminal size and current contents differs from top's
view, which is always based on operating system calls.
Following any re-size operation, if a top screen is corrupted, appears incomplete or dis‐
ordered, simply typing something innocuous like a punctuation character or cursor motion
key will usually restore it. In extreme cases, the following sequence almost certainly
will:
key/cmd objective
^Z suspend top
fg resume top
<Left> force a screen redraw (if necessary)
But if the display is still corrupted, there is one more step you could try. Insert this
command after top has been suspended but before resuming it.
key/cmd objective
reset restore your terminal settings
Note: the width of top's display will be limited to 512 positions. Displaying all fields
requires approximately 250 characters. Remaining screen width is usually allocated to any
variable width columns currently visible. The variable width columns, such as COMMAND,
are noted in topic 3a. DESCRIPTIONS of Fields. Actual output width may also be influenced
by the -w switch, which is discussed in topic 1. COMMAND-LINE Options.
Lastly, some of top's screens or functions require the use of cursor motion keys like the
standard arrow keys plus the Home, End, PgUp and PgDn keys. If your terminal or emulator
does not provide those keys, the following combinations are accepted as alternatives:
key equivalent-key-combinations
Up alt + \ or alt + k
Down alt + / or alt + j
Left alt + < or alt + h
Right alt + > or alt + l (lower case L)
PgUp alt + Up or alt + ctrl + k
PgDn alt + Down or alt + ctrl + j
Home alt + Left or alt + ctrl + h
End alt + Right or alt + ctrl + l
The Up and Down arrow keys have special significance when prompted for line input termi‐
nated with the <Enter> key. Those keys, or their aliases, can be used to retrieve previ‐
ous input lines which can then be edited and re-input. And there are four additional keys
available with line oriented input.
key special-significance
Up recall older strings for re-editing
Down recall newer strings or erase entire line
Insert toggle between insert and overtype modes
Delete character removed at cursor, moving others left
Home jump to beginning of input line
End jump to end of input line
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.
All are explained in detail in the sections that follow.
Global-defaults
'A' - Alt display Off (full-screen)
* 'd' - Delay time 3.0 seconds
* 'H' - Threads mode Off (summarize as tasks)
'I' - Irix mode On (no, 'solaris' smp)
* 'p' - PID monitoring Off (show all processes)
* 's' - Secure mode Off (unsecured)
'B' - Bold enable On (yes, bold globally)
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)
* 'i' - Idle tasks On (show all tasks)
'J' - Num align right On (not left justify)
'j' - Str align right Off (not right justify)
'R' - Reverse sort On (pids high-to-low)
* 'S' - Cumulative time Off (no, dead children)
* 'u' - User filter Off (show euid only)
* 'U' - User filter Off (show any uid)
'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|-bcHiOSs -d secs -n max -u|U user -p pid -o fld -w [cols]
The typically mandatory switches ('-') and even whitespace are completely optional.
-h | -v :Help/Version
Show library version and the usage prompt, then quit.
-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.t (secs.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 prohibited 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 6a. SYSTEM Configuration File.
-H :Threads-mode operation
Instructs top to display individual threads. Without this command-line option a sum‐
mation of all threads in each process is shown. Later this can be changed with the
'H' interactive command.
-i :Idle-process toggle
Starts top with the last remembered 'i' state reversed. When this toggle is Off,
tasks that have not used any CPU since the last update will not be displayed. For
additional information regarding this toggle see topic 4c. TASK AREA Commands, SIZE.
-n :Number-of-iterations limit as: -n number
Specifies the maximum number of iterations, or frames, top should produce before end‐
ing.
-o :Override-sort-field as: -o fieldname
Specifies the name of the field on which tasks will be sorted, independent of what is
reflected in the configuration file. You can prepend a '+' or '-' to the field name
to also override the sort direction. A leading '+' will force sorting high to low,
whereas a '-' will ensure a low to high ordering.
This option exists primarily to support automated/scripted batch mode operation.
-O :Output-field-names
This option acts as a form of help for the above -o option. It will cause top to
print each of the available field names on a separate line, then quit. Such names
are subject to nls translation.
-p :Monitor-PIDs mode as: -pN1 -pN2 ... or -pN1,N2,N3 ...
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.
A pid value of zero will be treated as the process id of the top program itself once
it is running.
This is a command-line option only and should you wish to return to normal operation,
it is not necessary to quit and restart top -- just issue any of these interactive
commands: '=', 'u' or 'U'.
The 'p', 'u' and 'U' command-line options are mutually exclusive.
-s :Secure-mode operation
Starts top with secure mode forced, even for root. This mode is far better con‐
trolled through the system configuration file (see topic 6. FILES).
-S :Cumulative-time toggle
Starts top with the last remembered 'S' state reversed. When 'Cumulative time' 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.
-u | -U :User-filter-mode as: -u | -U number or name
Display only processes with a user id or user name matching that given. The '-u'
option matches on effective user whereas the '-U' option matches on any user (real,
effective, saved, or filesystem).
Prepending an exclamation point ('!') to the user id or name instructs top to display
only processes with users not matching the one provided.
The 'p', 'u' and 'U' command-line options are mutually exclusive.
-w :Output-width-override as: -w [ number ]
In 'Batch' mode, when used without an argument top will format output using the COL‐
UMNS= and LINES= environment variables, if set. Otherwise, width will be fixed at
the maximum 512 columns. With an argument, output width can be decreased or
increased (up to 512) but the number of rows is considered unlimited.
In normal display mode, when used without an argument top will attempt to format out‐
put using the COLUMNS= and LINES= environment variables, if set. With an argument,
output width can only be decreased, not increased. Whether using environment vari‐
ables or an argument with -w, when not in 'Batch' mode actual terminal dimensions can
never be exceeded.
Note: Without the use of this command-line option, output width is always based on
the terminal at which top was invoked whether or not in 'Batch' mode.
2. SUMMARY Display
Each of the following three areas are individually controlled through one or more interac‐
tive commands. See topic 4b. SUMMARY AREA Commands for additional information regarding
these provisions.
2a. UPTIME and LOAD Averages
This portion consists of a single line containing:
program or window name, depending on display mode
current time and length of time since last boot
total number of users
system load avg over the last 1, 5 and 15 minutes
2b. TASK and CPU States
This portion consists of a minimum of two lines. In an SMP environment, additional lines
can reflect individual CPU state percentages.
Line 1 shows total tasks or threads, depending on the state of the Threads-mode toggle.
That total is further classified as:
running; sleeping; stopped; zombie
Line 2 shows CPU state percentages based on the interval since the last refresh. Where
two labels are shown below, those for more recent kernel versions are shown first.
us, user : time running un-niced user processes
sy, system : time running kernel processes
ni, nice : time running niced user processes
wa, IO-wait : time waiting for I/O completion
hi : time spent servicing hardware interrupts
si : time spent servicing software interrupts
st : time stolen from this vm by the hypervisor
2c. MEMORY Usage
This portion consists of two lines which may express values in kibibytes (KiB) through
exbibytes (EiB) depending on the scaling factor enforced with the 'E' interactive command.
Line 1 reflects physical memory, classified as:
total, used, free and buffers
Line 2 reflects mostly virtual memory, classified as:
total, used, free and cached (which is physical memory)
This table may help in interpreting the scaled values displayed:
KiB = kibibyte = 1024 bytes
MiB = mebibyte = 1024 KiB = 1,048,576 bytes
GiB = gibibyte = 1024 MiB = 1,073,741,824 bytes
TiB = tebibyte = 1024 GiB = 1,099,511,627,776 bytes
PiB = pebibyte = 1024 TiB = 1,125,899,906,842,624 bytes
EiB = exbibyte = 1024 PiB = 1,152,921,504,606,846,976 bytes
3. FIELDS / Columns
3a. DESCRIPTIONS of Fields
Listed below are top's available process fields (columns). They are shown in strict ascii
alphabetical order. You may customize their position and whether or not they are dis‐
playable with the 'f' or 'F' (Fields Management) interactive commands.
Any field is selectable as the sort field, and you control whether they are sorted high-
to-low or low-to-high. For additional information on sort provisions see topic 4c. TASK
AREA Commands, SORTING.
The fields related to physical memory or virtual memory reference '(KiB)' as the default,
unsuffixed display mode. Such fields can, however, be scaled differently via the 'e'
interactive command.
1. %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 a process is multi-threaded and top is not operating in
Threads mode, amounts greater than 100% may be reported. You toggle Threads mode with
the 'H' interactive command.
Also for multi-processor environments, 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.
2. %MEM -- Memory Usage (RES)
A task's currently used share of available physical memory.
3. CGROUPS -- Control Groups
The names of the control group(s) to which a process belongs, or '-' if not applicable
for that process.
Control Groups provide for allocating resources (cpu, memory, network bandwidth, etc.)
among installation-defined groups of processes. They enable fine-grained control over
allocating, denying, prioritizing, managing and monitoring those resources.
Many different hierarchies of cgroups can exist simultaneously on a system and each
hierarchy is attached to one or more subsystems. A subsystem represents a single
resource.
Note: The 'CGROUPS' field, unlike most columns, is not fixed-width. When displayed,
it plus any other variable width columns will be allocated all remaining screen width
(up to the maximum 512 characters). Even so, such variable width fields could still
suffer truncation. See topic 5c. SCROLLING a Window for additional information on
accessing any truncated data.
4. CODE -- Code Size (KiB)
The amount of physical memory devoted to executable code, also known as the 'text res‐
ident set' size or TRS.
5. COMMAND -- Command Name or Command Line
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 brackets, as in this exam‐
ple:
[kthreadd]
This field may also be impacted by the 'forest view' display mode. See the 'V' inter‐
active command for additional information regarding that mode.
Note: The 'COMMAND' field, unlike most columns, is not fixed-width. When displayed,
it plus any other variable width columns will be allocated all remaining screen width
(up to the maximum 512 characters). Even so, such variable width fields could still
suffer truncation. This is especially true for this field when command lines are
being displayed (the 'c' interactive command.) See topic 5c. SCROLLING a Window for
additional information on accessing any truncated data.
6. DATA -- Data + Stack Size (KiB)
The amount of physical memory devoted to other than executable code, also known as the
'data resident set' size or DRS.
7. ENVIRON -- Environment variables
Display all of the environment variables, if any, as seen by the respective processes.
These variables will be displayed in their raw native order, not the sorted order you
are accustomed to seeing with an unqualified 'set'.
Note: The 'ENVIRON' field, unlike most columns, is not fixed-width. When displayed,
it plus any other variable width columns will be allocated all remaining screen width
(up to the maximum 512 characters). Even so, such variable width fields could still
suffer truncation. This is especially true for this field. See topic 5c. SCROLLING a
Window for additional information on accessing any truncated data.
8. 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>.
9. GID -- Group Id
The effective group ID.
10. GROUP -- Group Name
The effective group name.
11. 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 dispatch-ability.
12. 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).
13. PGRP -- Process Group Id
Every process is member of a unique process group which is used for distribution of
signals and by terminals to arbitrate requests for their input and output. When a
process is created (forked), it becomes a member of the process group of its parent.
By convention, this value equals the process ID (see PID) of the first member of a
process group, called the process group leader.
14. PID -- Process Id
The task's unique process ID, which periodically wraps, though never restarting at
zero. In kernel terms, it is a dispatchable entity defined by a 'task_struct'.
This value may also be used as: a process group ID (see PGRP); a session ID for the
session leader (see SID); a thread group ID for the thread group leader (see TGID);
and a TTY process group ID for the process group leader (see TPGID).
15. PPID -- Parent Process Id
The process ID (pid) of a task's parent.
16. PR -- Priority
The scheduling priority of the task. If you see 'rt' in this field, it means the task
is running under 'real time' scheduling priority.
Under linux, real time priority is somewhat misleading since traditionally the operat‐
ing itself was not preemptible. And while the 2.6 kernel can be made mostly pre‐
emptible, it is not always so.
17. RES -- Resident Memory Size (KiB)
The non-swapped physical memory a task has used.
18. RUID -- Real User Id
The real user ID.
19. RUSER -- Real User Name
The real user name.
20. 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 represented 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.
21. SHR -- Shared Memory Size (KiB)
The amount of shared memory available to a task, not all of which is typically resi‐
dent. It simply reflects memory that could be potentially shared with other pro‐
cesses.
22. SID -- Session Id
A session is a collection of process groups (see PGRP), usually established by the
login shell. A newly forked process joins the session of its creator. By convention,
this value equals the process ID (see PID) of the first member of the session, called
the session leader, which is usually the login shell.
23. SUID -- Saved User Id
The saved user ID.
24. SUPGIDS -- Supplementary Group IDs
The IDs of any supplementary group(s) established at login or inherited from a task's
parent. They are displayed in a comma delimited list.
Note: The 'SUPGIDS' field, unlike most columns, is not fixed-width. When displayed,
it plus any other variable width columns will be allocated all remaining screen width
(up to the maximum 512 characters). Even so, such variable width fields could still
suffer truncation. See topic 5c. SCROLLING a Window for additional information on
accessing any truncated data.
25. SUPGRPS -- Supplementary Group Names
The names of any supplementary group(s) established at login or inherited from a
task's parent. They are displayed in a comma delimited list.
Note: The 'SUPGRPS' field, unlike most columns, is not fixed-width. When displayed,
it plus any other variable width columns will be allocated all remaining screen width
(up to the maximum 512 characters). Even so, such variable width fields could still
suffer truncation. See topic 5c. SCROLLING a Window for additional information on
accessing any truncated data.
26. SUSER -- Saved User Name
The saved user name.
27. SWAP -- Swapped Size (KiB)
The non-resident portion of a task's address space.
28. TGID -- Thread Group Id
The ID of the thread group to which a task belongs. It is the PID of the thread group
leader. In kernel terms, it represents those tasks that share an 'mm_struct'.
29. 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 have used. You tog‐
gle 'Cumulative mode' with 'S', which is both a command-line option and an interactive
command. See the 'S' interactive command for additional information regarding this
mode.
30. TIME+ -- CPU Time, hundredths
The same as 'TIME', but reflecting more granularity through hundredths of a second.
31. TPGID -- Tty Process Group Id
The process group ID of the foreground process for the connected tty, or -1 if a
process is not connected to a terminal. By convention, this value equals the process
ID (see PID) of the process group leader (see PGRP).
32. 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. How‐
ever, a task need not be associated with a terminal, in which case you'll see '?' dis‐
played.
33. UID -- User Id
The effective user ID of the task's owner.
34. USED -- Memory in Use (KiB)
This field represents the non-swapped physical memory a task has used (RES) plus the
non-resident portion of its address space (SWAP).
35. USER -- User Name
The effective user name of the task's owner.
36. VIRT -- Virtual Memory Size (KiB)
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 and pages that have been mapped
but not used.
37. 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.
By displaying this field, top's own working set could be increased by over 700Kb,
depending on the kernel version. Should that occur, your only means of reducing that
overhead will be to stop and restart top.
38. nDRT -- Dirty Pages Count
The number of pages that have been modified since they were last written to auxiliary
storage. Dirty pages must be written to auxiliary storage before the corresponding
physical memory location can be used for some other virtual page.
39. nMaj -- Major 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 auxiliary storage access is
involved in making that page available.
40. nMin -- Minor Page Fault count
The number of minor 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 minor page fault does not involve auxiliary storage
access in making that page available.
41. nTH -- Number of Threads
The number of threads associated with a process.
42. nsIPC -- IPC namespace
The Inode of the namespace used to isolate interprocess communication (IPC) resources
such as System V IPC objects and POSIX message queues.
43. nsMNT -- MNT namespace
The Inode of the namespace used to isolate filesystem mount points thus offering dif‐
ferent views of the filesystem hierarchy.
44. nsNET -- NET namespace
The Inode of the namespace used to isolate resources such as network devices, IP
addresses, IP routing, port numbers, etc.
45. nsPID -- PID namespace
The Inode of the namespace used to isolate process ID numbers meaning they need not
remain unique. Thus, each such namespace could have its own 'init' (PID #1) to manage
various initialization tasks and reap orphaned child processes.
46. nsUSER -- USER namespace
The Inode of the namespace used to isolate the user and group ID numbers. Thus, a
process could have a normal unprivileged user ID outside a user namespace while having
a user ID of 0, with full root privileges, inside that namespace.
47. nsUTS -- UTS namespace
The Inode of the namespace used to isolate hostname and NIS domain name. UTS simply
means "UNIX Time-sharing System".
48. vMj -- Major Page Fault Count Delta
The number of major page faults that have occurred since the last update (see nMaj).
49. vMn -- Minor Page Fault Count Delta
The number of minor page faults that have occurred since the last update (see nMin).
3b. MANAGING Fields
After pressing the interactive command 'f' or 'F' (Fields Management) you will be pre‐
sented with a screen showing: 1) the ´current´ window name; 2) the designated sort field;
3) all fields in their current order along with descriptions. Entries marked with an
asterisk are the currently displayed fields, screen width permitting.
o As the on screen instructions indicate, you navigate among the fields with the Up
and Down arrow keys. The PgUp, PgDn, Home and End keys can also be used to quickly
reach the first or last available field.
o The Right arrow key selects a field for repositioning and the Left arrow key or the
<Enter> key commits that field's placement.
o The 'd' key or the <Space> bar toggles a field's display status, and thus the pres‐
ence or absence of the asterisk.
o The 's' key designates a field as the sort field. See topic 4c. TASK AREA Com‐
mands, SORTING for additional information regarding your selection of a sort field.
o The 'a' and 'w' keys can be used to cycle through all available windows and the 'q'
or <Esc> keys exit Fields Management.
The Fields Management screen can also be used to change the ´current´ window/field group
in either full-screen mode or alternate-display mode. Whatever was targeted when 'q' or
<Esc> was pressed will be made current as you return to the top display. See topic 5.
ALTERNATE-DISPLAY Provisions and the 'g' interactive command for insight into ´current´
windows and field groups.
Note: Any window that has been scrolled horizontally will be reset if any field changes
are made via the Fields Management screen. Any vertical scrolled position, however, will
not be affected. See topic 5c. SCROLLING a Window for additional information regarding
vertical and horizontal scrolling.
4. 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.
4a. Global-Commands
<Ent/Sp> ?, =, 0,
A, B, d, E, e, g, h, H, I, k, q, r, s, W, X, Y, Z
4b. Summary-Area-Commands
C, l, t, m, 1, 2, 3
4c. Task-Area-Commands
Appearance: b, J, j, x, y, z
Content: c, f, F, o, O, S, u, U, V
Size: #, i, n
Sorting: <, >, f, F, R
4d. Color-Mapping
<Ret>, a, B, b, H, M, q, S, T, w, z, 0 - 7
5b. Commands-for-Windows
-, _, =, +, A, a, g, G, w
5c. Scrolling-a-Window
C, Up, Dn, Left, Right, PgUp, PgDn, Home, End
5d. Searching-in-a-Window
L, &
4a. GLOBAL Commands
The global interactive commands are always available in both full-screen mode and alter‐
nate-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 awaken top and following receipt of any input the entire display
will be repainted. They also force an update of any hotplugged cpu or physical
memory changes.
Use either of these keys if you have a large delay interval and wish to see current
status,
? | 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 alternate-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, 'user' filtering and 'other' filtering. See the
'-p' command-line option for a discussion of PID monitoring, the 'U' or 'u' inter‐
active commands for user filtering and the 'O' or 'o' interactive commands for
'other' filtering.
Additionally, any window that has been scrolled will be reset with this command.
See topic 5c. SCROLLING a Window for additional information regarding vertical and
horizontal scrolling.
When operating in alternate-display mode this command has a broader meaning.
0 :Zero-Suppress toggle
This command determines whether zeros are shown or suppressed for many of the
fields in a task window. Fields like UID, GID, NI, PR or P are not affected by
this toggle.
A :Alternate-Display-Mode toggle
This command will switch between full-screen mode and alternate-display mode. See
topic 5. ALTERNATE-DISPLAY Provisions 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 pri‐
marily 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 confirmation that they are even
on.
* d | 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.
E :Extend-Memory-Scale in Summary Area
With this command you can cycle through the available summary area memory scaling
which ranges from KiB (kibibytes or 1,024 bytes) through EiB (exbibytes or
1,152,921,504,606,846,976 bytes).
If you see a '+' between a displayed number and the following label, it means that
top was forced to truncate some portion of that number. By raising the scaling
factor, such truncation can be avoided.
e :Extend-Memory-Scale in Task Windows
With this command you can cycle through the available task window memory scaling
which ranges from KiB (kibibytes or 1,024 bytes) through PiB (pebibytes or
1,125,899,906,842,624 bytes).
While top will try to honor the selected target range, additional scaling might
still be necessary in order to accommodate current values. If you wish to see a
more homogeneous result in the memory columns, raising the scaling range will usu‐
ally accomplish that goal. Raising it too high, however, is likely to produce an
all zero result which cannot be suppressed with the '0' interactive command.
g :Choose-Another-Window/Field-Group
You will be prompted to enter a number between 1 and 4 designating the field group
which should be made the ´current´ window. You will soon grow comfortable with
these 4 windows, especially after experimenting with alternate-display mode.
H :Threads-mode toggle
When this toggle is On, individual threads will be displayed for all processes in
all visible task windows. Otherwise, top displays a summation of all threads in
each process.
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 told
the new state of this toggle.
* k :Kill-a-task
You will be prompted for a PID and then the signal to send.
Entering no PID or a negative number will be interpreted as the default shown in
the prompt (the first task displayed). A PID value of zero means the top program
itself.
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, type an invalid number
2) at the signal prompt, type 0 (or any invalid signal)
q :Quit
* r :Renice-a-Task
You will be prompted for a PID and then the value to nice it to.
Entering no PID or a negative number will be interpreted as the default shown in
the prompt (the first task displayed). A PID value of zero means the top program
itself.
A positive nice value will cause a process to lose priority. Conversely, a nega‐
tive nice value will cause a process to be viewed more favorably by the kernel. As
a general rule, ordinary users can only increase the nice value and are prevented
from lowering it.
If you wish to abort the renice process, do one of the following depending on your
progress:
1) at the pid prompt, type an invalid number
2) at the nice prompt, type <Enter> with no input
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 command just before quitting top, you will be able
restart later in exactly that same state.
X :Extra-Fixed-Width
Some fields are fixed width and not scalable. As such, they are subject to trunca‐
tion which would be indicated by a '+' in the last position.
This interactive command can be used to alter the widths of the following fields:
field default field default field default
GID 5 GROUP 8 WCHAN 10
RUID 5 RUSER 8 nsIPC 10
SUID 5 SUSER 8 nsMNT 10
UID 5 USER 8 nsNET 10
TTY 8 nsPID 10
nsUSR 10
nsUTS 10
You will be prompted for the amount to be added to the default widths shown above.
Entering zero forces a return to those defaults.
If you enter a negative number, top will automatically increase the column size as
needed until there is no more truncated data. You can accelerate this process by
reducing the delay interval or holding down the <Space> bar.
Note: Whether explicitly or automatically increased, the widths for these fields
are never decreased by top. To narrow them you must specify a smaller number or
restore the defaults.
Y :Inspect-Other-Output
After issuing the 'Y' interactive command, you will be prompted for a target PID.
Typing a value or accepting the default results in a separate screen. That screen
can be used to view a variety of files or piped command output while the normal top
iterative display is paused.
Note: This interactive command is only fully realized when supporting entries have
been manually added to the end of the top configuration file. For details on cre‐
ating those entries, see topic 6c. ADDING INSPECT Entries.
Most of the keys used to navigate the Inspect feature are reflected in its header
prologue. There are, however, additional keys available once you have selected a
particular file or command. They are familiar to anyone who has used the pager
'less' and are summarized here for future reference.
key function
'=' alternate status-line, file or pipeline
'/' find, equivalent to 'L' locate
'n' find next, equivalent to '&' locate next
<Space> scroll down, equivalent to <PgDn>
'b' scroll up, equivalent to <PgUp>
'g' first line, equivalent to <Home>
'G' last line, equivalent to <End>
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 com‐
mand see topic 4d. 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.
4b. 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 deter‐
mine the position of messages and prompts.
These commands always impact just the ´current´ window/field group. See topic 5. ALTER‐
NATE-DISPLAY Provisions and the 'g' interactive command for insight into ´current´ windows
and field groups.
C :Show-scroll-coordinates toggle
Toggle an informational message which is displayed whenever the message line is not
otherwise being used. For additional information see topic 5c. SCROLLING a Window.
l :Load-Average/Uptime toggle
This is also the line containing the program name (possibly an alias) when operat‐
ing in full-screen mode or the ´current´ window name when operating in alter‐
nate-display mode.
t :Task/Cpu-States toggle
This command affects from 2 to many summary area lines, depending on the state of
the '1', '2' or '3' command toggles and whether or not top is running under true
SMP.
This portion of the summary area is also influenced by the 'H' interactive command
toggle, as reflected in the total label which shows either 'Tasks' or 'Threads'.
m :Memory/Swap-Usage toggle
This command affects the two summary area lines dealing with physical and virtual
memory.
1 :Single/Separate-Cpu-States toggle
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 sepa‐
rately as: '%Cpu0, %Cpu1, ...' up to available screen height.
2 :NUMA-Nodes/Cpu-Summary toggle
This command toggles between the '1' command cpu summary display (only) or a sum‐
mary display plus the cpu usage statistics for each NUMA Node. It is only avail‐
able if a system has the requisite NUMA support.
3 :Expand-NUMA-Node
You will be invited to enter a number representing a NUMA Node. Thereafter, a node
summary plus the statistics for each cpu in that node will be shown until either
the '1' or '2' command toggle is pressed. This interactive command is only avail‐
able if a system has the requisite NUMA support.
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.
4c. 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 5. ALTERNATE-DISPLAY Pro‐
visions).
APPEARANCE of task window
J :Justify-Numeric-Columns toggle
Alternates between right-justified (the default) and left-justified numeric data.
If the numeric data completely fills the available column, this command toggle may
impact the column header only.
j :Justify-Character-Columns toggle
Alternates between left-justified (the default) and right-justified character data.
If the character data completely fills the available column, this command toggle
may impact the column header only.
The following commands will also be influenced by the state of the global 'B' (bold
enable) 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. If you forget which field is
being sorted this command can serve as a quick visual reminder, providing the sort
field is being displayed. The sort field might not be visible because:
1) there is insufficient Screen Width
2) the 'f' interactive command turned it Off
Note: Whenever 'Searching' and/or 'Other Filtering' is active in a window, column
highlighting is temporarily disabled. See the notes at the end of topics 5d.
SEARCHING and 5e. FILTERING for an explanation why.
y :Row-Highlight toggle
Changes highlighting for "running" tasks. For additional insight into this task
state, see topic 3a. DESCRIPTIONS of Fields, the 'S' field (Process Status).
Use of this provision provides important insight into your system's health. The
only costs will be a few additional 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 visi‐
ble. Later, should that field come into view, the change you applied will be seen.
f | F :Fields-Management
These keys display a separate screen where you can change which fields are dis‐
played, their order and also designate the sort field. For additional information
on these interactive commands see topic 3b. MANAGING Fields.
o | O :Other-Filtering
You will be prompted for the selection criteria which then determines which tasks
will be shown in the ´current´ window. Your criteria can be made case sensitive or
case can be ignored. And you determine if top should include or exclude matching
tasks.
See topic 5e. FILTERING in a window for details on these and additional related
interactive commands.
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 com‐
pilers, 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 | U :Show-Specific-User-Only
You will be prompted for the uid or name of the user to display. The '-u' option
matches on effective user whereas the '-U' option matches on any user (real,
effective, saved, or filesystem).
Thereafter, in that task window only matching users will be shown, or possibly no
processes will be shown. Prepending an exclamation point ('!') to the user id or
name instructs top to display only processes with users not matching the one pro‐
vided.
Different task windows can be used to filter different users. Later, if you wish
to monitor all users again in the ´current´ window, re-issue this command but just
press <Enter> at the prompt.
V :Forest-View-Mode toggle
In this mode, processes are reordered according to their parents and the layout of
the COMMAND column resembles that of a tree. In forest view mode it is still pos‐
sible to toggle between program name and command line (see the 'c' interactive com‐
mand) or between processes and threads (see the 'H' interactive command).
Note: Typing any key affecting the sort order will exit forest view mode in the
´current´ window. See topic 4c. TASK AREA Commands, SORTING for information on
those keys.
SIZE of task window
i :Idle-Process toggle
Displays all tasks or just active tasks. When this toggle is Off, tasks that have
not used any CPU since the last update will not be displayed. However, due to the
granularity of the %CPU and TIME+ fields, some processes may still be displayed
that appear to have used no CPU.
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 | # :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 currently 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 | F :Fields-Management
These keys display a separate screen where you can change which field is used as
the sort column, among other functions. This 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.
4d. 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.
The following interactive commands are available.
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 you 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 completely 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 alternate-display mode. Whatever was targeted when 'q' or
<Enter> was pressed will be made current as you return to the top display.
5. ALTERNATE-DISPLAY Provisions
5a. 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 sep‐
arately 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.
5b. COMMANDS for Windows
- | _ :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'
interactive command. 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 tog‐
gled Off. If all 4 task displays are currently visible, this interactive command
will leave the summary area as the only display element.
* = | + :Equalize-(reinitialize)-Window(s)
The '=' key forces the ´current´ window's task display to be visible. It also
reverses any 'i' (idle tasks), 'n' (max tasks), 'u'/'U' (user filter) and 'o'/'O'
(other filter) commands that might be active. Also, if the window had been
scrolled, it will be reset with this command. See topic 5c. SCROLLING a Window for
additional information regarding vertical and horizontal scrolling.
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 previ‐
ously applied, except for the 'i' (idle tasks), 'n' (max tasks), 'u'/'U' (user fil‐
ter), 'o'/'O' (other filter) and scrolling interactive 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 cho‐
sen to make visible.
* a | 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 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 with color mapping
and fields management
5c. SCROLLING a Window
Typically a task window is a partial view into a systems's total tasks/threads which shows
only some of the available fields/columns. With these scrolling keys, you can move that
view vertically or horizontally to reveal any desired task or column.
Up,PgUp :Scroll-Tasks
Move the view up toward the first task row, until the first task is displayed at the
top of the ´current´ window. The Up arrow key moves a single line while PgUp scrolls
the entire window.
Down,PgDn :Scroll-Tasks
Move the view down toward the last task row, until the last task is the only task dis‐
played at the top of the ´current´ window. The Down arrow key moves a single line
while PgDn scrolls the entire window.
Left,Right :Scroll-Columns
Move the view of displayable fields horizontally one column at a time.
Note: As a reminder, some fields/columns are not fixed-width but allocated all remain‐
ing screen width when visible. When scrolling right or left, that feature may produce
some unexpected results initially.
Additionally, there are special provisions for any variable width field when posi‐
tioned as the last displayed field. Once that field is reached via the right arrow
key, and is thus the only column shown, you can continue scrolling horizontally within
such a field. See the 'C' interactive command below for additional information.
Home :Jump-to-Home-Position
Reposition the display to the un-scrolled coordinates.
End :Jump-to-End-Position
Reposition the display so that the rightmost column reflects the last displayable
field and the bottom task row represents the last task.
Note: From this position it is still possible to scroll down and right using the arrow
keys. This is true until a single column and a single task is left as the only dis‐
play element.
C :Show-scroll-coordinates toggle
Toggle an informational message which is displayed whenever the message line is not
otherwise being used. That message will take one of two forms depending on whether or
not a variable width column has also been scrolled.
scroll coordinates: y = n/n (tasks), x = n/n (fields)
scroll coordinates: y = n/n (tasks), x = n/n (fields) + nn
The coordinates shown as n/n are relative to the upper left corner of the ´current´
window. The additional '+ nn' represents the displacement into a variable width col‐
umn when it has been scrolled horizontally. Such displacement occurs in normal 8
character tab stop amounts via the right and left arrow keys.
y = n/n (tasks)
The first n represents the topmost visible task and is controlled by scrolling
keys. The second n is updated automatically to reflect total tasks.
x = n/n (fields)
The first n represents the leftmost displayed column and is controlled by
scrolling keys. The second n is the total number of displayable fields and is
established with the 'f' interactive command.
The above interactive commands are always available in full-screen mode but never avail‐
able in alternate-display mode if the ´current´ window's task display has been toggled
Off.
Note: When any form of filtering is active, you can expect some slight aberrations when
scrolling since not all tasks will be visible. This is particularly apparent when using
the Up/Down arrow keys.
5d. SEARCHING in a Window
You can use these interactive commands to locate a task row containing a particular value.
L :Locate-a-string
You will be prompted for the case-sensitive string to locate starting from the current
window coordinates. There are no restrictions on search string content.
Searches are not limited to values from a single field or column. All of the values
displayed in a task row are allowed in a search string. You may include spaces, num‐
bers, symbols and even forest view artwork.
Keying <Enter> with no input will effectively disable the '&' key until a new search
string is entered.
& :Locate-next
Assuming a search string has been established, top will attempt to locate the next
occurrence.
When a match is found, the current window is repositioned vertically so the task row con‐
taining that string is first. The scroll coordinates message can provide confirmation of
such vertical repositioning (see the 'C' interactive command). Horizontal scrolling, how‐
ever, is never altered via searching.
The availability of a matching string will be influenced by the following factors.
a. Which fields are displayable from the total available,
see topic 3b. MANAGING Fields.
b. Scrolling a window vertically and/or horizontally,
see topic 5c. SCROLLING a Window.
c. The state of the command/command-line toggle,
see the 'c' interactive command.
d. The stability of the chosen sort column,
for example PID is good but %CPU bad.
If a search fails, restoring the ´current´ window home (unscrolled) position, scrolling
horizontally, displaying command-lines or choosing a more stable sort field could yet pro‐
duce a successful '&' search.
The above interactive commands are always available in full-screen mode but never avail‐
able in alternate-display mode if the ´current´ window's task display has been toggled
Off.
Note: Whenever a search key is typed, top will turn column highlighting Off to prevent
false matches on internal non-display escape sequences. Such highlighting will be
restored when a window's search string is empty. See the 'x' interactive command for
additional information on sort column highlighting.
5e. FILTERING in a Window
You can use the 'Other Filter' feature to establish selection criteria which will then
determine which tasks are shown in the ´current´ window.
Establishing a filter requires: 1) a field name; 2) an operator; and 3) a selection value,
as a minimum. This is the most complex of top's user input requirements so, when you make
a mistake, command recall will be your friend. Remember the Up/Down arrow keys or their
aliases when prompted for input.
Filter Basics
. field names are case sensitive and spelled as in the header
. selection values need not comprise the full displayed field
. a selection is either case insensitive or sensitive to case
. the default is inclusion, prepending '!' denotes exclusions
. multiple selection criteria can be applied to a task window
. inclusion and exclusion criteria can be used simultaneously
. the 1 equality and 2 relational filters can be freely mixed
. separate unique filters are maintained for each task window
If a field is not turned on or is not currently in view, then your selection criteria will
not affect the display. Later, should a filtered field become visible, the selection cri‐
teria will then be applied.
Keyboard Summary
o :Other-Filter (lower case)
You will be prompted to establish a filter that ignores case when matching.
O :Other-Filter (upper case)
You will be prompted to establish a case sensitive filter.
^O :Show-Active-Filters (Ctrl key + 'o')
This can serve as a reminder of which filters are active in the ´current´ window. A
summary will be shown on the message line until you press the <Enter> key.
= :Reset-Filtering in current window
This clears all of your selection criteria in the ´current´ window. It also has
additional impact so please see topic 4a. GLOBAL Commands.
+ :Reset-Filtering in all windows
This clears the selection criteria in all windows, assuming you are in alter‐
nate-display mode. As with the '=' interactive command, it too has additional con‐
sequences so you might wish to see topic 5b. COMMANDS for Windows.
Input Requirements
When prompted for selection criteria, the data you provide must take one of two forms.
There are 3 required pieces of information, with a 4th as optional. These examples use
spaces for clarity but your input generally would not.
#1 #2 #3 ( required )
Field-Name ? include-if-value
! Field-Name ? exclude-if-value
#4 ( optional )
Items #1, #3 and #4 should be self-explanatory. Item #2 represents both a required
delimiter and the operator which must be one of either equality ('=') or relation ('<'
or '>').
The '=' equality operator requires only a partial match and that can reduce your
'if-value' input requirements. The '>' or '<' relational operators always employ
string comparisons, even with numeric fields. They are designed to work with a field's
default justification and with homogeneous data. When some field's numeric amounts
have been subjected to scaling while others have not, that data is no longer homoge‐
neous.
If you establish a relational filter and you have changed the default 'Numeric' or
'Character' justification, that filter is likely to fail. When a relational filter is
applied to a memory field and you have not changed the scaling, it may produce mislead‐
ing results. This happens, for example, because '100.0m' (MiB) would appear greater
than '1.000g' (GiB) when compared as strings.
If your filtered results appear suspect, simply altering justification or scaling may
yet achieve the desired objective. See the 'j', 'J' and 'e' interactive commands for
additional information.
Potential Problems
These GROUP filters could produce the exact same results or the second one might not
display anything at all, just a blank task window.
GROUP=root ( only the same results when )
GROUP=ROOT ( invoked via lower case 'o' )
Either of these RES filters might yield inconsistent and/or misleading results, depend‐
ing on the current memory scaling factor. Or both filters could produce the exact same
results.
RES>9999 ( only the same results when )
!RES<10000 ( memory scaling is at 'KiB' )
This nMin filter illustrates a problem unique to scalable fields. This particular
field can display a maximum of 4 digits, beyond which values are automatically scaled
to KiB or above. So while amounts greater than 9999 exist, they will appear as 2.6m,
197k, etc.
nMin>9999 ( always a blank task window )
Potential Solutions
These examples illustrate how 'Other Filtering' can be creatively applied to achieve
almost any desired result. Single quotes are sometimes shown to delimit the spaces
which are part of a filter or to represent a request for status (^O) accurately. But
if you used them with if-values in real life, no matches would be found.
Assuming field nTH is displayed, the first filter will result in only multi-threaded
processes being shown. It also reminds us that a trailing space is part of every dis‐
played field. The second filter achieves the exact same results with less typing.
!nTH=' 1 ' ( ' for clarity only )
nTH>1 ( same with less i/p )
With Forest View mode active and the COMMAND column in view, this filter effectively
collapses child processes so that just 3 levels are shown.
!COMMAND=' `- ' ( ' for clarity only )
The final two filters appear as in response to the status request key (^O). In real‐
ity, each filter would have required separate input. The PR example shows the two con‐
current filters necessary to display tasks with priorities of 20 or more, since some
might be negative. Then by exploiting trailing spaces, the nMin series of filters
could achieve the failed '9999' objective discussed above.
'PR>20' + '!PR=-' ( 2 for right result )
'!nMin=0 ' + '!nMin=1 ' + '!nMin=2 ' + '!nMin=3 ' ...
Note: When 'Other Filtering' is active, top turns column highlighting Off to prevent false
matches on internal non-display escape sequences. Such highlighting will be restored when
a window is no longer subject to filtering. See the 'x' interactive command for addi‐
tional information on sort column highlighting.
6. FILES
6a. SYSTEM Configuration File
The presence of this file will influence which version of the 'help' screen is shown to an
ordinary user. More importantly, it will limit what ordinary users are allowed to do when
top is running. They will not be able to issue the following 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 manu‐
ally and place it in the /etc directory. Its name must be 'toprc' and must have no lead‐
ing '.' (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
6b. 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
global # line 15: fixed-width incr
" # any remaining lines are devoted to the
" # generalized 'inspect' provisions
" # discussed below
If the $HOME variable is not present, top will try to write the personal configuration
file to the current directory, subject to permissions.
6c. ADDING INSPECT Entries
To exploit the 'Y' interactive command, you must add entries at the end of the top per‐
sonal configuration file. Such entries simply reflect a file to be read or command/pipe‐
line to be executed whose results will then be displayed in a separate scrollable, search‐
able window.
If you don't know the location or name of your top rcfile, use the 'W' interactive command
to rewrite it and note those details.
Inspect entries can be added with a redirected echo or by editing the configuration file.
Redirecting an echo risks overwriting the rcfile should it replace (>) rather than append
(>>) to that file. Conversely, when using an editor care must be taken not to corrupt
existing lines, some of which will contain unprintable data or unusual characters.
Those Inspect entries beginning with a '#' character are ignored, regardless of content.
Otherwise they consist of the following 3 elements, each of which must be separated by a
tab character (thus 2 '\t' total):
.type: literal 'file' or 'pipe'
.name: selection shown on the Inspect screen
.fmts: string representing a path or command
The two types of Inspect entries are not interchangeable. Those designated 'file' will be
accessed using fopen and must reference a single file in the '.fmts' element. Entries
specifying 'pipe' will employ popen, their '.fmts' element could contain many pipelined
commands and, none can be interactive.
If the file or pipeline represented in your '.fmts' deals with the specific PID input or
accepted when prompted, then the format string must also contain the '%d' specifier, as
these examples illustrate.
.fmts= /proc/%d/numa_maps
.fmts= lsof -P -p %d
For 'pipe' type entries only, you may also wish to redirect stderr to stdout for a more
comprehensive result. Thus the format string becomes:
.fmts= pmap -x %d 2>&1
Here are examples of both types of Inspect entries as they might appear in the rcfile.
The first entry will be ignored due to the initial '#' character. For clarity, the pseudo
tab depictions (^I) are surrounded by an extra space but the actual tabs would not be.
# pipe ^I Sockets ^I lsof -n -P -i 2>&1
pipe ^I Open Files ^I lsof -P -p %d 2>&1
file ^I NUMA Info ^I /proc/%d/numa_maps
pipe ^I Log ^I tail -n100 /var/log/syslog | sort -Mr
Except for the commented entry above, these next examples show what could be echoed to
achieve similar results, assuming the rcfile name was '.toprc'. However, due to the
embedded tab characters, each of these lines should be preceded by '/bin/echo -e', not
just a simple an 'echo', to enable backslash interpretation regardless of which shell you
use.
"pipe\tOpen Files\tlsof -P -p %d 2>&1" >> ~/.toprc
"file\tNUMA Info\t/proc/%d/numa_maps" >> ~/.toprc
"pipe\tLog\ttail -n200 /var/log/syslog | sort -Mr" >> ~/.toprc
Caution: If any inspect entry you create produces output with unprintable characters they
will be displayed in either the ^C notation or hexadecimal <FF> form, depending on their
value. This applies to tab characters as well, which will show as '^I'. If you want a
truer representation, any embedded tabs should be expanded.
# next would have contained '\t' ...
# file ^I <your_name> ^I /proc/%d/status
# but this will eliminate embedded '\t' ...
pipe ^I <your_name> ^I cat /proc/%d/status | expand -
The above example takes what could have been a 'file' entry but employs a 'pipe' instead
so as to expand the embedded tabs.
Note: While 'pipe' type entries have been discussed in terms of pipelines and commands,
there is nothing to prevent you from including shell scripts as well. Perhaps even newly
created scripts designed specifically for the 'Y' interactive command.
Lastly, as the number of your Inspect entries grows over time, the 'Options:' row will be
truncated when screen width is exceeded. That does not affect operation other than to
make some selections invisible.
However, if some choices are lost to truncation but you want to see more options, there is
an easy solution hinted at below.
Inspection Pause at pid ...
Use: left/right then <Enter> ...
Options: help 1 2 3 4 5 6 7 8 9 10 11 ...
The entries in the top rcfile would have a number for the '.name' element and the 'help'
entry would identify a shell script you've written explaining what those numbered selec‐
tions actually mean. In that way, many more choices can be made visible.
7. STUPID TRICKS Sampler
Many of these 'tricks' work best when you give top a scheduling boost. So plan on start‐
ing him with a nice value of -10, assuming you've got the authority.
7a. Kernel Magic
For these stupid tricks, top needs full-screen mode.
o 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 fol‐
lowing:
. provide a scheduling boost and tiny delay via:
nice -n -10 top -d.09
. keep sorted column highlighting Off so as 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.
o Under an xterm using 'white-on-black' colors, on top's Color Mapping screen set the
task color to black and be sure that task highlighting 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.
o Delete the existing rcfile, or create a new symlink. Start this new version then type
'T' (a secret key, see topic 4c. 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.
7b. Bouncing Windows
For these stupid tricks, top needs alternate-display mode.
o With 3 or 4 task displays visible, pick any window other than the last and turn idle
processes Off using the 'i' command toggle. Depending on where you applied 'i', some‐
times several task displays are bouncing and sometimes it's like an accordion, as top
tries his best to allocate space.
o Set each window's summary lines differently: one with no memory ('m'); another with no
states ('t'); maybe one with nothing at all, just the message line. Then hold down 'a'
or 'w' and watch a variation on bouncing windows -- hopping windows.
o Display all 4 windows and for each, in turn, set idle processes to Off using the 'i'
command toggle. You've just entered the "extreme bounce" zone.
7c. The Big Bird Window
This stupid trick also requires alternate-display mode.
o Display all 4 windows and make sure that 1:Def is the ´current´ window. Then, keep
increasing window size with the 'n' interactive command until all the other task dis‐
plays are "pushed out of the nest".
When they've all been displaced, toggle between all visible/invisible windows using the
'_' command toggle. Then ponder this:
is top fibbing or telling honestly your imposed truth?
7d. The Ol' Switcheroo
This stupid trick works best without alternate-display mode, since justification is active
on a per window basis.
o Start top and make COMMAND the last (rightmost) column displayed. If necessary, use
the 'c' command toggle to display command lines and ensure that forest view mode is
active with the 'V' command toggle.
Then use the up/down arrow keys to position the display so that some truncated command
lines are shown ('+' in last position). You may have to resize your xterm to produce
truncation.
Lastly, use the 'j' command toggle to make the COMMAND column right justified.
Now use the right arrow key to reach the COMMAND column. Continuing with the right
arrow key, watch closely the direction of travel for the command lines being shown.
some lines travel left, while others travel right
eventually all lines will Switcheroo, and move right
8. BUGS
To report bugs, follow the instructions at:
http://www.debian.org/Bugs/Reporting
9. HISTORY Former top
The original top was written by Roger Binns, based on Branko Lankester's
<lankeste AT fwi.nl> ps program.
Robert Nation <nation AT rocket.com> adapted it for the proc file system.
Helmut Geyer <Helmut.Geyer AT iwr.de> added support for configurable fields.
Plus many other individuals contributed over the years.
10. AUTHOR
This entirely new and enhanced replacement was written by:
Jim Warner, <james.warner AT comcast.net>
With invaluable help from:
Craig Small, <csmall AT enc.au>
Albert Cahalan, <albert AT users.net>
11. SEE Also
free(1), ps(1), uptime(1), atop(1), slabtop(1), vmstat(8), w(1).
procps-ng November 2013 TOP(1)
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