top命令

命令用途

top 命令是 Linux 系统中用于实时监控系统进程和资源使用情况的动态工具，可查看 CPU、内存、任务负载等信息，并按需排序或过滤进程。
常用用法示例

默认启动，实时监控系统状态
1
2
top
（输出包含进程列表、CPU/内存使用率、负载等动态信息）
默认界面每3秒刷新一次，展示所有进程的资源占用情况。
按 CPU 使用率排序进程
1
2
3
top
（进入界面后按大写 P）
（进程列表按 CPU% 从高到低排序）
通过交互命令 P 快速定位高 CPU 消耗的进程。
按内存使用率排序进程
1
2
3
top
（进入界面后按大写 M）
（进程列表按 MEM% 从高到低排序）
通过交互命令 M 快速定位高内存占用的进程。
仅监控指定用户的进程
1
2
top -u www-data
（仅显示用户 www-data 的进程）
过滤特定用户的进程，便于针对性分析。
设置刷新间隔为2秒
1
2
top -d 2
（界面刷新间隔调整为2秒）
通过 -d 参数自定义刷新频率。
显示完整命令路径
1
2
top -c
（COMMAND 列显示进程的完整启动命令）
查看进程的完整执行路径，方便排查问题。
批处理模式输出
1 2	top -n 3 -b > top_log.txt （将3次刷新结果输出到文件，适合脚本处理）
结合 -n 和 -b 参数实现非交互式记录。
监控指定进程ID
1
2
top -p 1234,5678
（仅显示 PID 为1234和5678的进程）
精准监控特定进程的资源使用情况。
常用参数选项

-d <秒>, –delay=<秒>
设置刷新间隔时间（默认3秒），如 top -d 5。
-p <PID1,PID2,…>, –pid=<PID1,PID2,…>
仅监控指定的进程ID，多个PID用逗号分隔。
-u <用户名>, –user=<用户名>
仅显示指定用户的进程。
-c, –command
显示进程的完整命令路径而非仅命令名称。
-b, –batch
以批处理模式运行，适用于输出重定向到文件。
-n <次数>, –iterations=<次数>
设置刷新次数后自动退出，如 top -n 5。
-H, –threads
显示线程信息而非进程汇总（需在界面中按 H 切换）。
-i, –idle
隐藏空闲（idle）进程，仅显示活跃进程。
原厂文档

NAME

       top - display Linux processes

SYNOPSIS

       top [option ...]

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 managed 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

           OVERVIEW
              Operation
              Linux Memory Types
           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. BOTTOM WINDOW Commands
              e. 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. PERSONAL Configuration File
              b. ADDING INSPECT Entries
              c. SYSTEM Configuration File
              d. SYSTEM Restrictions File
           7. ENVIRONMENT VARIABLE(S)
           8. STUPID TRICKS Sampler
              a. Kernel Magic
              b. Bouncing Windows
              c. The Big Bird Window
              d. The Ol' Switcheroo
           9. BUGS, 10. 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 ultimately
       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 disordered, 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-keys
              Left     alt + h
              Down     alt + j
              Up       alt + k
              Right    alt + l
              Home     alt + ctrl + h
              PgDn     alt + ctrl + j
              PgUp     alt + ctrl + k
              End      alt + ctrl + l

       The Up and Down arrow keys have special significance when prompted
       for line input terminated with the <Enter> key.  Those keys, or
       their aliases, can be used to retrieve previous 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

   Linux Memory Types
       For our purposes there are three types of memory, and one is
       optional.  First is physical memory, a limited resource where code
       and data must reside when executed or referenced.  Next is the
       optional swap file, where modified (dirty) memory can be saved and
       later retrieved if too many demands are made on physical memory.
       Lastly we have virtual memory, a nearly unlimited resource serving
       the following goals:

          1. abstraction, free from physical memory addresses/limits
          2. isolation, every process in a separate address space
          3. sharing, a single mapping can serve multiple needs
          4. flexibility, assign a virtual address to a file

       Regardless of which of these forms memory may take, all are
       managed as pages (typically 4096 bytes) but expressed by default
       in top as KiB (kibibyte).  The memory discussed under topic ‘2c.
       MEMORY Usage’ deals with physical memory and the swap file for the
       system as a whole.  The memory reviewed in topic ‘3. FIELDS /
       Columns Display’ embraces all three memory types, but for
       individual processes.

       For each such process, every memory page is restricted to a single
       quadrant from the table below.  Both physical memory and virtual
       memory can include any of the four, while the swap file only
       includes #1 through #3.  The memory in quadrant #4, when modified,
       acts as its own dedicated swap file.

                                     Private | Shared
                                 1           |          2
            Anonymous  . stack               |
                       . malloc()            |
                       . brk()/sbrk()        | . POSIX shm*
                       . mmap(PRIVATE, ANON) | . mmap(SHARED, ANON)
                      -----------------------+----------------------
                       . mmap(PRIVATE, fd)   | . mmap(SHARED, fd)
          File-backed  . pgms/shared libs    |
                                 3           |          4

       The following may help in interpreting process level memory values
       displayed as scalable columns and discussed under topic ‘3a.
       DESCRIPTIONS of Fields’.

          %MEM - simply RES divided by total physical memory
          CODE - the ‘pgms’ portion of quadrant 3
          DATA - the entire quadrant 1 portion of VIRT plus all
                 explicit mmap file-backed pages of quadrant 3
          RES  - anything occupying physical memory which, beginning with
                 Linux-4.5, is the sum of the following three fields:
                 RSan - quadrant 1 pages, which include any
                        former quadrant 3 pages if modified
                 RSfd - quadrant 3 and quadrant 4 pages
                 RSsh - quadrant 2 pages
          RSlk - subset of RES which cannot be swapped out (any quadrant)
          SHR  - subset of RES (excludes 1, includes all 2 & 4, some 3)
          SWAP - potentially any quadrant except 4
          USED - simply the sum of RES and SWAP
          VIRT - everything in-use and/or reserved (all quadrants)

       Note: Even though program images and shared libraries are
       considered private to a process, they will be accounted for as
       shared (SHR) by the kernel.

1. COMMAND-LINE Options

       Mandatory arguments to long options are mandatory for short
       options too.

       Although not required, the equals sign can be used with either
       option form and whitespace before and/or after the ‘=’ is
       permitted.

       -A, --apply-defaults
          Run top with build defaults only, ignoring all configuration
          files except /etc/toprc.  This option, when specified, must be
          the only command line option present.

       -b, --batch
          Starts top in Batch mode, which could be useful for sending
          output from top to other programs or to a file.  In this mode,
  will not accept input and runs until the iterations limit
          you've set with the ‘-n’ command-line option or until killed.

       -c, --cmdline-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 vice versa.  See the ‘c’ interactive command
          for additional information.

       -d, --delay = 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
  is running in Secure mode, except for root (unless the ‘s’
          command-line option was used).  For additional information on
          Secure mode see topic 6d. SYSTEM Restrictions File.

       -E, --scale-summary-mem = k | m | g | t | p | e
          Instructs top to force summary area memory to be scaled as:
             k - kibibytes
             m - mebibytes
             g - gibibytes
             t - tebibytes
             p - pebibytes
             e - exbibytes

          Later this can be changed with the ‘E’ command toggle.

       -e, --scale-task-mem = k | m | g | t | p
          Instructs top to force task area memory to be scaled as:
             k - kibibytes
             m - mebibytes
             g - gibibytes
             t - tebibytes
             p - pebibytes

          Later this can be changed with the ‘e’ command toggle.

       -H, --threads-show
          Instructs top to display individual threads.  Without this
          command-line option a summation of all threads in each process
          is shown.  Later this can be changed with the ‘H’ interactive
          command.

       -h, --help
          Display usage help text, then quit.

       -i, --idle-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, --iterations = NUMBER
          Specifies the maximum number of iterations, or frames, top
          should produce before ending.

       -O, --list-fields
          This option acts as a form of help for the -o option shown
          below.  It will cause top to print each of the available field
          names on a separate line, then quit.  Such names are subject to
          NLS (National Language Support) translation.

       -o, --sort-override = 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.

       -p, --pid = PIDLIST (as: 1,2,3, ... or
          -p1 -p2 -p3 ...)  Monitor only processes with specified process
          IDs.  However, when combined with Threads mode (‘H’), all
          processes in the thread group (see TGID) of each monitored PID
          will also be shown.

          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
  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, --accum-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.

       -s, --secure-mode
          Starts top with secure mode forced, even for root.  This mode
          is far better controlled through a system configuration file
          (see topic 6. FILES).

       -U, --filter-any-user = USER (as: number or name)
          Display only processes with a user id or user name matching
          that given.  This 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.

       -u, --filter-only-euser = USER (as: number or name)
          Display only processes with a user id or user name matching
          that given.  This option matches on the effective user id only.

          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.

       -V, --version
          Display version information, then quit.

       -w, --width [=COLUMNS]
          In Batch mode, when used without an argument top will format
          output using the COLUMNS= 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 output using the COLUMNS= and LINES=
          environment variables, if set.  With an argument, output width
          can only be decreased, not increased.  Whether using
          environment variables 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.

       -1, --single-cpu-toggle
          Starts top with the last remembered Cpu States portion of the
          summary area reversed.  Either all cpu information will be
          displayed in a single line or each cpu will be displayed
          separately, depending on the state of the NUMA Node command
          toggle (‘2’).

          See the ‘1’ and ‘2’ interactive commands for additional
          information.

2. SUMMARY Display

       Each of the following three areas are individually controlled
       through one or more interactive 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 according
       to task state as follows:
           displayed       process status (‘S’)
           ---------       --------------------
           running         R
           sleep           S + any remaining
           d-sleep         D
           stopped         T + t
           zombie          Z

       Line 2 shows CPU state percentages based on the interval since the
       last refresh.

       As a default, percentages for these individual categories are
       displayed.  Depending on your kernel version, the st field may not
       be shown.
           us : time running un-niced user processes
           sy : time running kernel processes
           ni : time running niced user processes
           id : time spent in the kernel idle handler
           wa : 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

       Beyond the first tasks/threads line, there are alternate CPU
       display modes available via the 4-way ‘t’ command toggle.  They
       show an abbreviated summary consisting of these elements:
                      a    b     c    d
           %Cpu(s):  75.0/25.0  100[ ... ]

       Where: a) is the ‘user’ (us + ni) percentage; b) is the ‘system’
       (sy + hi + si + guests) percentage; c) is the total percentage;
       and d) is one of two visual graphs of those representations.  Such
       graphs also reflect separate ‘user’ and ‘system’ portions.

       If the ‘4’ command toggle is used to yield more than two cpus per
       line, results will be further abridged eliminating the a) and b)
       elements.  However, that information is still reflected in the
       graph itself assuming color is active or, if not, bars vs. blocks
       are being shown.

       See topic 4b. SUMMARY AREA Commands for additional information on
       the ‘t’ and ‘4’ command toggles.

   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. The
       /proc/meminfo source fields are shown in parenthesis.

       Line 1 reflects physical memory, classified as:
           total          ( MemTotal )
           free           ( MemFree )
           used           ( MemTotal - MemAvailable )
           buff/cache     ( Buffers + Cached + SReclaimable )

       Line 2 reflects mostly virtual memory, classified as:
           total          ( SwapTotal )
           free           ( SwapFree )
           used           ( SwapTotal - SwapFree )
           avail          ( MemAvailable, which is physical memory )

       The avail number on line 2 is an estimation of physical memory
       available for starting new applications, without swapping.  Unlike
       the free field, it attempts to account for readily reclaimable
       page cache and memory slabs.  It is available on kernels 3.14,
       emulated on kernels 2.6.27+, otherwise the same as free.

       In the alternate memory display modes, two abbreviated summary
       lines are shown consisting of these elements:
                      a    b          c
           GiB Mem : 18.7/15.738   [ ... ]
           GiB Swap:  0.0/7.999    [ ... ]

       Where: a) is the percentage used; b) is the total available; and
       c) is one of two visual graphs of those representations.

       In the case of physical memory, the percentage represents the
       total minus the estimated avail noted above.  The ‘Mem’ graph
       itself is divided between the non-cached portion of used and any
       remaining memory not otherwise accounted for by avail.  See topic
       4b. SUMMARY AREA Commands and the ‘m’ command for additional
       information on that special 4-way toggle.

       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 displayable with the
       ‘f’ (Fields Management) 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 additional
       information on sort provisions see topic 4c. TASK AREA Commands,
       SORTING.

       The fields related to physical memory or virtual memory reference
       ‘(KiB)’ which is the unsuffixed display mode.  Such fields may,
       however, be scaled from KiB through PiB.  That scaling is
       influenced via the ‘e’ interactive command or established for
       startup through a build option.

       %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
   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,
   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.

           Note: When running in forest view mode (‘V’) with children
           collapsed (‘v’), this field will also include the CPU time of
           those unseen children.  See topic 4c. TASK AREA Commands,
           CONTENT for more information regarding the ‘V’ and ‘v’
           toggles.

       %CUC  --  CPU Utilization
           This field is identical to %CUU below, except the percentage
           also reflects reaped child processes.

       %CUU  --  CPU Utilization
           A task's total CPU usage divided by its elapsed running time,
           expressed as a percentage.

           If a process currently displays high CPU usage, this field can
           help determine if such behavior is normal.  Conversely, if a
           process has low CPU usage currently, %CUU may reflect
           historically higher demands over its lifetime.

       %MEM  --  Memory Usage (RES)
           A task's currently resident share of available physical
           memory.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       AGID  --  Autogroup Identifier
           The autogroup identifier associated with a process.  This
           feature operates in conjunction with the CFS scheduler to
           improve interactive desktop performance.

           When /proc/sys/kernel/sched_autogroup_enabled is set, a new
           autogroup is created with each new session (see SID).  All
           subsequently forked processes in that session inherit
           membership in this autogroup.  The kernel then attempts to
           equalize distribution of CPU cycles across such groups.  Thus,
           an autogroup with many CPU intensive processes (e.g make -j)
           will not dominate an autogroup with only one or two processes.

           When -1 is displayed it means this information is not
           available.

       AGNI  --  Autogroup Nice Value
           The autogroup nice value which affects scheduling of all
           processes in that group.  A negative nice value means higher
           priority, whereas a positive nice value means lower priority.

       CGNAME  --  Control Group Name
           The name of the control group to which a process belongs, or
           ‘-’ if not applicable for that process.

           Available with cgroup v1 only, this will typically be the last
           entry in the full list of control groups as displayed under
           the CGROUPS heading.  And as is true there, this field is also
           variable width.

       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.

       CLS  --  Scheduling Class
           The task's current scheduling policy which can be one of:
               -   = not reported
               TS  = SCHED_OTHER
               FF  = SCHED_FIFO
               RR  = SCHED_RR
               B   = SCHED_BATCH
               ISO = SCHED_ISO
               IDL = SCHED_IDLE
               DLN = SCHED_DEADLINE
               ?   = unknown value

       CODE  --  Code Size (KiB)
           The amount of physical memory currently devoted to executable
           code, also known as the Text Resident Set size or TRS.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       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 example:
               [kthreadd]

           This field may also be impacted by the forest view display
           mode.  See the ‘V’ interactive 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.

       DATA  --  Data + Stack Size (KiB)
           The amount of private memory reserved by a process.  It is
           also known as the Data Resident Set or DRS.  Such memory may
           not yet be mapped to physical memory (RES) but will always be
           included in the virtual memory (VIRT) amount.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       Docker --  Docker Container ID
           The identity (abbreviated hash) of the docker container within
           which a task is running.  If a process is not running inside a
           container, a dash (‘-’) will be shown.

       ELAPSED  --  Elapsed Running Time
           The length of time since a process was started.  Thus, the
           most recently started task will display the smallest time
           interval.

           The value will be expressed as ‘HH,MM’ (hours,minutes) but is
           subject to additional scaling if the interval becomes too
           great to fit column width.  At that point it will be scaled to
           ‘DD+HH’ (days+hours) and possibly beyond.

       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.

       EXE  --  Executable Path
           Where available, this is the full path to the executable,
           including the program name.

           Note: The EXE 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).

       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>.

       GID  --  Group Id
           The effective group ID.

       GROUP  --  Group Name
           The effective group name.

       LOGID  --  Login User Id
           The user ID used at login.  When -1 is displayed it means this
           information is not available.

       LXC  --  Lxc Container Name
           The name of the lxc container within which a task is running.
           If a process is not running inside a container, a dash (‘-’)
           will be shown.

       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.

           Note: This value only affects scheduling priority relative to
           other processes in the same autogroup.  See the ‘AGID’ and
           ‘AGNI’ fields for additional information on autogroups.

       NU  --  Last known NUMA node
           A number representing the NUMA node associated with the last
           used processor (‘P’).  When -1 is displayed it means that NUMA
           information is not available.

           See the ‘2’ and ‘3’ interactive commands for additional NUMA
           provisions affecting the summary area.

       OOMa  --  Out of Memory Adjustment Factor
           The value, ranging from -1000 to +1000, added to the current
           out of memory score (OOMs) which is then used to determine
           which task to kill when memory is exhausted.

       OOMs  --  Out of Memory Score
           The value, ranging from 0 to +1000, used to select task(s) to
           kill when memory is exhausted.  Zero translates to ‘never
           kill’ whereas 1000 means ‘always kill’.

       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).

       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.

       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).

       PPID  --  Parent Process Id
           The process ID (pid) of a task's parent.

       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 operating itself was not preemptible.  And
           while the 2.6 kernel can be made mostly preemptible, it is not
           always so.

       PSS  --  Proportional Resident Memory, smaps (KiB)
           The proportion of this task's share of ‘RSS’ where each page
           is divided by the number of processes sharing it.  It is also
           the sum of the ‘PSan’, ‘PSfd’ and ‘PSsh’ fields.

           For example, if a process has 1000 resident pages alone and
           1000 resident pages shared with another process, its ‘PSS’
           would be 1500 (times page size).

           Accessing smaps values is 10x more costly than other memory
           statistics and data for other users requires root privileges.

       PSan  --  Proportional Anonymous Memory, smaps (KiB)
       PSfd  --  Proportional File Memory, smaps (KiB)
       PSsh  --  Proportional Shmem Memory, smaps (KiB)
           As was true for ‘PSS’ above (total proportional resident
           memory), these fields represent the proportion of this task's
           share of each type of memory divided by the number of
           processes sharing it.

           Accessing smaps values is 10x more costly than other memory
           statistics and data for other users requires root privileges.

       RES  --  Resident Memory Size (KiB)
           A subset of the virtual address space (VIRT) representing the
           non-swapped physical memory a task is currently using.  It is
           also the sum of the ‘RSan’, ‘RSfd’ and ‘RSsh’ fields.

           It can include private anonymous pages, private pages mapped
           to files (including program images and shared libraries) plus
           shared anonymous pages.  All such memory is backed by the swap
           file represented separately under SWAP.

           Lastly, this field may also include shared file-backed pages
           which, when modified, act as a dedicated swap file and thus
           will never impact SWAP.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       RSS  --  Resident Memory, smaps (KiB)
           Another, more precise view of process non-swapped physical
           memory.  It is obtained from the ‘smaps_rollup’ file and is
           generally slightly larger than that shown for ‘RES’.

           Accessing smaps values is 10x more costly than other memory
           statistics and data for other users requires root privileges.

       RSan  --  Resident Anonymous Memory Size (KiB)
           A subset of resident memory (RES) representing private pages
           not mapped to a file.

       RSfd  --  Resident File-Backed Memory Size (KiB)
           A subset of resident memory (RES) representing the implicitly
           shared pages supporting program images and shared libraries.
           It also includes explicit file mappings, both private and
           shared.

       RSlk  --  Resident Locked Memory Size (KiB)
           A subset of resident memory (RES) which cannot be swapped out.

       RSsh  --  Resident Shared Memory Size (KiB)
           A subset of resident memory (RES) representing the explicitly
           shared anonymous shm*/mmap pages.

       RUID  --  Real User Id
           The real user ID.

       RUSER  --  Real User Name
           The real user name.

       S  --  Process Status
           The status of the task which can be one of:
               D = uninterruptible sleep
               I = idle
               R = running
               S = sleeping
               T = stopped by job control signal
               t = stopped by debugger during trace
               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.

       SHR  --  Shared Memory Size (KiB)
           A subset of resident memory (RES) that may be used by other
           processes.  It will include shared anonymous pages and shared
           file-backed pages.  It also includes private pages mapped to
           files representing program images and shared libraries.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       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.

       STARTED  --  Start Time Interval
           The length of time since system boot when a process started.
           Thus, the most recently started task will display the largest
           time interval.

           The value will be expressed as ‘MM:SS’ (minutes:seconds).  But
           if the interval is too great to fit column width it will be
           scaled as ‘HH,MM’ (hours,minutes) and possibly beyond.

       SUID  --  Saved User Id
           The saved user ID.

       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).

       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).

       SUSER  --  Saved User Name
           The saved user name.

       SWAP  --  Swapped Size (KiB)
           The formerly resident portion of a task's address space
           written to the swap file when physical memory becomes over
           committed.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       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.

       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 toggle
           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.

       TIME+  --  CPU Time, hundredths
           The same as TIME, but reflecting more granularity through
           hundredths of a second.

       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).

       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.

       UID  --  User Id
           The effective user ID of the task's owner.

       USED  --  Memory in Use (KiB)
           This field represents the non-swapped physical memory a task
           is using (RES) plus the swapped out portion of its address
           space (SWAP).

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       USER  --  User Name
           The effective user name of the task's owner.

       USS  --  Unique Set Size
           The non-swapped portion of physical memory (‘RSS’) not shared
           with any other process.  It is derived from the ‘smaps_rollup’
           file.

           Accessing smaps values is 10x more costly than other memory
           statistics and data for other users requires root privileges.

       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.

           See ‘OVERVIEW, Linux Memory Types’ for additional details.

       WCHAN  --  Sleeping in Function
           This field will show the name of the kernel function in which
           the task is currently sleeping.  Running tasks will display a
           dash (‘-’) in this column.

       ioR  --  I/O Bytes Read
           The number of bytes a process caused to be fetched from the
           storage layer.

           Root privileges are required to display ‘io’ data for other
           users.

       ioRop  --  I/O Read Operations
           The number of read I/O operations (syscalls) for a process.
           Such calls might not result in actual physical disk I/O.

       ioW  --  I/O Bytes Written
           The number of bytes a process caused to be sent to the storage
           layer.

       ioWop  --  I/O Write Operations
           The number of write I/O operations (syscalls) for a process.
           Such calls might not result in actual physical disk I/O.

       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.

           This field was deprecated with linux 2.6 and is always zero.

       nFD  --  Number of File Descriptors
           The total number of open files associated with a process.

       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.

       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.

       nTH  --  Number of Threads
           The number of threads associated with a process.

       nsCGROUP  --  CGROUP namespace
           The Inode of the namespace used to hide the identity of the
           control group of which process is a member.

       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.

       nsMNT  --  MNT namespace
           The Inode of the namespace used to isolate filesystem mount
           points thus offering different views of the filesystem
           hierarchy.

       nsNET  --  NET namespace
           The Inode of the namespace used to isolate resources such as
           network devices, IP addresses, IP routing, port numbers, etc.

       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/systemd’ (PID #1) to manage
           various initialization tasks and reap orphaned child
           processes.

       nsTIME  --  TIME namespace
           The Inode of the namespace which allows processes to see
           different system times in a way similar to the UTS namespace.

       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.

       nsUTS  --  UTS namespace
           The Inode of the namespace used to isolate hostname and NIS
           domain name.  UTS simply means "Unix Time-sharing System".

       vMj  --  Major Page Fault Count Delta
           The number of major page faults that have occurred since the
           last update (see nMaj).

       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’ (Fields Management) you
       will be presented 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.

           •  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.

           •  The Right arrow key selects a field for repositioning and
              the Left arrow key or the <Enter> key commits that field's
              placement.

           •  The ‘d’ key or the <Space> bar toggles a field's display
              status, and thus the presence or absence of the asterisk.

           •  The ‘s’ key designates a field as the sort field.  See
     ic 4c. TASK AREA Commands, SORTING for additional
              information regarding your selection of a sort field.

           •  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,
               ^E, ^R
         4b. Summary-Area-Commands
               C, l, t, m, 1, 2, 3, 4, 5, !
         4c. Task-Area-Commands
               Appearance:  b, J, j, x, y, z
               Content:     c, F, f, O, o, S, U, u, V, v
               Size:        #, i, n
               Sorting:     <, >, f, R
         4d. Bottom-Window-Commands
               ^A, ^G, ^K, ^L, ^N, ^P, ^U, Tab, Shift+Tab
         4e. 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, &
         5e. Filtering-in-a-Window
               O, o, ^O, =, +

   4a. 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 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-Display-Limits
              Removes restrictions on what is shown.  This command will
              reverse any ‘i’ (idle tasks), ‘n’ (max tasks), ‘v’ (hide
              children) and ‘F’ focus commands that might be active.  It
              also provides for an exit from PID monitoring, User
              filtering, Other filtering, Locate processing and Combine
              Cpus mode.

              Additionally, if the window has been scrolled it will be
              reset with this command.

          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 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 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  :Enforce-Summary-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  :Enforce-Task-Memory-Scale in Task Area
              With this command you can cycle through the available task
              area 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 usually 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)
                  3) at any prompt, type <Esc>

          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 negative 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
                  3) at any prompt, type <Esc>

          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 truncation 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       Docker    8       WCHAN      10
                  LOGID     5       GROUP     8       nsCGROUP   10
                  RUID      5       LXC       8       nsIPC      10
                  SUID      5       RUSER     8       nsMNT      10
                  UID       5       SUSER     8       nsNET      10
                                    TTY       8       nsPID      10
                                    USER      8       nsTIME     10
                                                      nsUSER     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.

              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 creating those
              entries, see topic 6b. 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 command
              see topic 4e. COLOR Mapping.

         ^E  :Scale-CPU-Time-fields (Ctrl key + ‘e’)
              The ‘time’ fields are normally displayed with the greatest
              precision their widths permit.  This toggle reduces that
              precision until it wraps.  It also illustrates the scaling
              those fields might experience automatically, which usually
              depends on how long the system runs.

              For example, if ‘MMM:SS.hh’ is shown, each ^E keystroke
              would change it to: ‘MM:SS’, ‘Hours,MM’, ‘Days+Hours’ and
              finally ‘Weeks+Days’.

              Not all time fields are subject to the full range of such
              scaling.

       * ^R  :Renice-an-Autogroup  (Ctrl key + ‘r’)
              You will be prompted for a PID and then the value for its
              autogroup AGNI.

              Entering no PID will be interpreted as the default shown in
              the prompt (the first task displayed).

              A positive AGNI value will cause processes in that
              autogroup to lose priority.  Conversely, a negative value
              causes them to be viewed more favorably by the kernel.
              Ordinary users are not allowed to set negative AGNI values.

              If you wish to abort the renice process type <Esc>.

       *  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 determine the position of
       messages and prompts.

       These commands always impact just the ‘current’ window/field
       group.  See topic 5. ALTERNATE-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 operating in full-screen mode or the
              ‘current’ window name when operating in alternate-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.

              This command serves as a 4-way toggle, cycling through
              these modes:
                  1. detailed percentages by category
                  2. abbreviated user/system and total % + bar graph
                  3. abbreviated user/system and total % + block graph
                  4. turn off task and cpu states display

              When operating in either of the graphic modes, the display
              becomes much more meaningful when individual CPUs or NUMA
              nodes are also displayed.  See the the ‘1’, ‘2’ and ‘3’
              commands below for additional information.

          m  :Memory/Swap-Usage toggle
              This command affects the two summary area lines dealing
              with physical and virtual memory.

              This command serves as a 4-way toggle, cycling through
              these modes:
                  1. detailed percentages by memory type
                  2. abbreviated % used/total available + bar graph
                  3. abbreviated % used/total available + block graph
                  4. turn off memory display

          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 separately 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 summary display plus the cpu usage
              statistics for each NUMA Node.  It is only available 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 the ‘1’, ‘2’ or
              ‘4’ command toggle is pressed.  This interactive command is
              only available if a system has the requisite NUMA support.

          4  :Display-Multiple-Elements-Adjacent toggle
              This command toggle turns the ‘1’ toggle Off and shows
              multiple CPU and Memory results on each line.  Each
              successive ‘4’ key adds another CPU until again reverting
              to separate lines for CPU and Memory results.

              A maximum of 8 CPUs per line can be displayed in this
              manner.  However, data truncation may occur before reaching
              the maximum.  That is definitely true when displaying
              detailed statistics via the ‘t’ command toggle since such
              data cannot be scaled like the graphic representations.

              If one wished to quickly exit adjacent mode without cycling
              all the way to 8, simply use the ‘1’ command toggle.

          5  :Display-P-Cores-and-E-Cores toggle
              This command toggle is only active when the ‘t’ toggle is
              On and the ‘1’, ‘2’, ‘3’ and ‘!’ toggles are Off, thus
              showing individual CPU results.  It assumes a platform has
              multiple cores of two distinct types, either multi-threaded
              (P-Core) or single-threaded (E-Core).

              While normally each cpu is displayed as ‘%Cpu0, %Cpu1,
              ...’, this toggle can be used to identify and/or filter
              those cpus by their core type, either P-Core (performance)
              or E-Core (efficient).

              The 1st time ‘5’ is struck, each CPU is displayed as ‘%CpP’
              or ‘%CpE’ representing the two core types.  The 2nd time,
              only P-Cores (%CpP) will be shown.  The 3rd time, only E-
              Cores (%CpE) are displayed.  When this command toggle is
              struck for the 4th time, the CPU display returns to the
              normal ‘%Cpu’ convention.

              If separate performance and efficient categories are not
              present, this command toggle will have no effect.

          !  :Combine-Cpus-Mode toggle
              This command toggle is intended for massively parallel SMP
              environments where, even with the ‘4’ command toggle, not
              all processors can be displayed.  With each press of ‘!’
              the number of cpus combined is doubled thus reducing the
              total number of cpu lines displayed.

              For example, with the first press of ‘!’ two cpus will be
              combined and displayed as ‘0-1, 2-3, ...’ instead of the
              normal ‘%Cpu0, %Cpu1, %Cpu2, %Cpu3, ...’.  With a second
              ‘!’ command toggle four cpus are combined and shown as
              ‘0-3, 4-7, ...’.  Then the third ‘!’ press, combining eight
              cpus, shows as ‘0-7, 8-15, ...’, etc.

              Such progression continues until individual cpus are again
              displayed and impacts both the ‘1’ and ‘4’ toggles (one or
              multiple columns).  Use the ‘=’ command to exit Combine
              Cpus mode.

       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 Provisions).

       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.  It may also impact the summary area when a bar
              graph has been selected for cpu states or memory usage via
              the ‘t’ or ‘m’ toggles.

          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

          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 visible.  Later, should that field come
              into view, the change you applied will be seen.

          F  :Maintain-Parent-Focus toggle
              When in forest view mode, this key serves as a toggle to
              retain focus on a target task, presumably one with forked
              children.  If forest view mode is Off this key has no
              effect.

              The toggle is applied to the first (topmost) process in the
              ‘current’ window.  Once established, that task is always
              displayed as the first (topmost) process along with its
              forked children.  All other processes will be suppressed.

              Note: keys like ‘i’ (idle tasks), ‘n’ (max tasks), ‘v’
              (hide children) and User/Other filtering remain accessible
              and can impact what is displayed.

          f  :Fields-Management
              This key displays a separate screen where you can change
              which fields are displayed, their order and also designate
              the sort field.  For additional information on this
              interactive command 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 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 | 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
      to display only processes with users not matching the
              one provided.

              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 possible to
              toggle between program name and command line (see the ‘c’
              interactive command) 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.

          v  :Hide/Show-Children toggle
              When in forest view mode, this key serves as a toggle to
              collapse or expand the children of a parent.

              The toggle is applied against the first (topmost) process
              in the ‘current’ window.  See topic 5c. SCROLLING a Window
              for additional information regarding vertical scrolling.

              If the target process has not forked any children, this key
              has no effect.  It also has no effect when not in forest
              view mode.

       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  :Fields-Management
                 This key displays 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.

   4d. BOTTOM WINDOW Commands
       These keys invoke a separate window at the bottom of the screen
       while normal top monitoring continues uninterrupted.  Keying the
       same ‘Ctrl’ command a second time removes that separate window as
       does the ‘=’ command.

          ^A  :Display-Capabilities          (Ctrl key + ‘a’)
          ^G  :Display-Control-Groups        (Ctrl key + ‘g’)
          ^K  :Display-Cmdline               (Ctrl key + ‘k’)
          ^L  :Display-Logged-Messages       (Ctrl key + ‘l’)
          ^N  :Display-Environment           (Ctrl key + ‘n’)
          ^P  :Display-Namesspaces           (Ctrl key + ‘p’)
          ^U  :Display-Supplementary-Groups  (Ctrl key + ‘u’)

       Except for the Ctrl+L command, all the above keys are applied to
       the first process displayed and will show that task's full
       (potentially wrapped) information.  Thus, the Up/Down arrow keys
       or their aliases will be important.

       The Tab key or Shift+Tab combination can be used to highlight
       individual elements being displayed in the bottom window.

       Notable among these provisions is the Ctrl+N (environment)
       command.  Its output can be extensive and not easily read when
       line wrapped.  A more readable version can be achieved with an
       ‘Inspect’ entry in the rcfile like the following.

           pipe ^I Environment ^I cat /proc/%d/environ | tr '\0' '\n'

       See the ‘Y’ interactive command under 4a. GLOBAL Commands and
       topic 6b. ADDING INSPECT Entries for additional information.

       Unlike the other commands, Ctrl+L (logged messages) is not
       associated with a specific task.  Rather, up to 10 of the most
       recent messages issued by top are recalled for review.

   4e. 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.
           5 upper case letters to select a target
           8 numbers to select a color (@ selects no 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 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.

   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 toggled Off.  If
              all 4 task displays are currently visible, this interactive
              command will leave the summary area as the only display
              element.

       *  = | +  :Equalize/Reset-Window(s)
              The ‘=’ key forces the ‘current’ window's task display to
              be visible.  It also reverses any active ‘i’ (idle tasks),
              ‘n’ (max tasks), ‘u/U’ (user filter), ‘o/O’ (other filter),
              ‘v’ (hide children), ‘F’ focused, ‘L’ (locate) and ‘!’
              (combine cpus) commands.  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, while retaining
              any customizations previously applied beyond those noted
              for the ‘=’ command toggle.

       *  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 | 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
              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  :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

       *  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.

   5c. SCROLLING a Window
       Typically a task window is a partial view into a system'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 displayed 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 remaining 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 positioned 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 display 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 column 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 available 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, numbers, 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 containing that string is first.  The
       scroll coordinates message can provide confirmation of such
       vertical repositioning (see the ‘C’ interactive command).
       Horizontal scrolling, however, 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 produce a
       successful ‘&’ search.

       The above interactive commands are always available in full-screen
       mode but never available in alternate-display mode if the
       ‘current’ window's task display has been toggled Off.

   5e. FILTERING in a Window
       You can use this ‘Other Filter’ feature to establish selection
       criteria which will then determine which tasks are shown in the
       ‘current’ window.  Such filters can be made persistent if
       preserved in the rcfile via the ‘W’ interactive command.

       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

          1. field names are case sensitive and spelled as in the header

          2. selection values need not comprise the full displayed field

          3. a selection is either case insensitive or sensitive to case

          4. the default is inclusion, prepending ‘!’ denotes exclusions

          5. multiple selection criteria can be applied to a task window

          6. inclusion and exclusion criteria can be used simultaneously

          7. the 1 equality and 2 relational filters can be freely mixed

          8. 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 criteria
          will then be applied.

       Keyboard Summary

         O  :Other-Filter (upper case)
             You will be prompted to establish a case sensitive filter.

         o  :Other-Filter (lower case)
             You will be prompted to establish a filter that ignores case
             when matching.

        ^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 alternate-display mode.  As with the ‘=’
             interactive command, it too has additional consequences 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 homogeneous.

          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 misleading 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, depending 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 displayed 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 reality, each filter would have required
          separate input.  The PR example shows the two concurrent
          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 ’ ...

6. FILES

   6a. PERSONAL Configuration File
       This file is created or updated via the ‘W’ interactive command.

       The legacy version is written as ‘$HOME/.your-name-4-top’ + ‘rc’
       with a leading period.

       A newly created configuration file is written as
       ‘procps/your-name-4-top’ + ‘rc’ without a leading period.  The
       procps directory will be subordinate to either $XDG_CONFIG_HOME
       when set as an absolute path or the $HOME/.config directory.

       While not intended to be edited manually, 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,etc
             "      # line  c: summclr,msgsclr,headclr,taskclr
           global   # line 15: additional miscellaneous settings
             "      # any remaining lines are devoted to optional
             "      # active ‘other filters’ discussed in section 5e above
             "      # plus ‘inspect’ entries discussed in section 6b below

       If a valid absolute path to the rcfile cannot be established,
       customizations made to a running top will be impossible to
       preserve.

   6b. ADDING INSPECT Entries
       To exploit the ‘Y’ interactive command, you must add entries at
       the end of the top personal configuration file.  Such entries
       simply reflect a file to be read or command/pipeline to be
       executed whose results will then be displayed in a separate
       scrollable, searchable 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 could contain unprintable data or
       unusual characters depending on the top version under which that
       configuration file was saved.

       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

       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.  The
       following example takes what could have been a ‘file’ entry but
       employs a ‘pipe’ instead so as to expand the embedded tabs.

         # 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 -

       Note: Some programs might rely on SIGINT to end.  Therefore, if a
       ‘pipe’ such as the following is established, one must use Ctrl-C
       to terminate it in order to review the results.  This is the
       single occasion where a ‘^C’ will not also terminate top.

         pipe ^I Trace ^I /usr/bin/strace -p %d 2>&1

       Lastly, 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.

       For example, 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 selections actually mean.
       In that way, many more choices can be made visible.

   6c. SYSTEM Configuration File
       This configuration file represents defaults for users who have not
       saved their own configuration file.  The format mirrors exactly
       the personal configuration file and can also include ‘inspect’
       entries as explained above.

       Creating it is a simple process.

       1. Configure top appropriately for your installation and preserve
       that configuration with the ‘W’ interactive command.

       2. Add and test any desired ‘inspect’ entries.

       3. Copy that configuration file to the /etc/ directory as
       ‘topdefaultrc’.

   6d. SYSTEM Restrictions 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

       This configuration file is not created by top.  Rather, it is
       created manually and placed it in the /etc/ directory as ‘toprc’.

       It should have exactly two lines, as shown in this example:
           s        # line 1: secure mode switch
           5.0      # line 2: delay interval in seconds

7. ENVIRONMENT VARIABLE(S)

       The value set for the following is unimportant, just its presence.

       LIBPROC_HIDE_KERNEL
              This will prevent display of any kernel threads and exclude
              such processes from the summary area Tasks/Threads counts.

8. 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.

   8a. 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 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.

       •  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.

       •  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.

   8b. 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 using the ‘i’ command
          toggle.  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
          (‘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.

       •  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.

   8c. 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 with the ‘n’
          interactive command until all the other task displays 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?

   8d. The Ol' Switcheroo
       This stupid trick works best without alternate-display mode, since
       justification is active on a per window basis.

       •  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

9. BUGS

       Please send bug reports to ⟨procps@freelists.org⟩.

10. SEE Also

       free(1), ps(1), uptime(1), atop(1), slabtop(1), vmstat(8), w(1)

COLOPHON

       This page is part of the procps-ng (/proc filesystem utilities)
       project.  Information about the project can be found at 
       ⟨https://gitlab.com/procps-ng/procps⟩.  If you have a bug report
       for this manual page, see
       ⟨https://gitlab.com/procps-ng/procps/blob/master/Documentation/bugs.md⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://gitlab.com/procps-ng/procps.git⟩ on 2024-02-02.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-01-15.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org