man > htop(1)

TLDR: htop (tldr-pages)

Display dynamic real-time information about running processes.

  • Start `htop`
    htop
  • Start `htop` displaying processes owned by a specific user
    htop {{-u|--user}} {{username}}
  • Display processes hierarchically in a tree view to show the parent-child relationships
    htop {{-t|--tree}}
  • Sort processes by a specified `sort_item` (use `htop --sort help` for available options)
    htop {{-s|--sort}} {{sort_item}}
  • Start `htop` with the specified delay between updates, in tenths of a second (i.e. 50 = 5 seconds)
    htop {{-d|--delay}} {{50}}
  • Disable all system and process changing features
    htop --readonly
  • See interactive commands while running `htop`
    {{<F1>|<?>}}
  • Switch to a different tab
    <Tab>
HTOP(1)                                     User Commands                                    HTOP(1)

NAME
       htop, pcp-htop - interactive process viewer

SYNOPSIS
       htop [-dCFhpustvH]
       pcp htop [-dCFhpustvH] [--host/-h host]

DESCRIPTION
       htop is a cross-platform ncurses-based process viewer.

       It  is similar to top, but allows you to scroll vertically and horizontally, and interact us‐
       ing a pointing device (mouse).  You can observe all processes running on  the  system,  along
       with  their  command  line  arguments, as well as view them in a tree format, select multiple
       processes and act on them all at once.

       Tasks related to processes (killing, renicing) can be done without entering their PIDs.

       pcp-htop is a version of htop built using the Performance Co-Pilot  (PCP)  Metrics  API  (see
       PCPIntro(1),  PMAPI(3)),  allowing  to  extend htop to display values from arbitrary metrics.
       See the section below titled CONFIG FILES for further details.

COMMAND-LINE OPTIONS
       Mandatory arguments to long options are mandatory for short options too.

       -d --delay=DELAY
              Delay between updates, in tenths of a second. If the delay value is less than 1, it is
              increased to 1, i.e. 1/10 second. If the delay value is greater than 100,  it  is  de‐
              creased to 100, i.e. 10 seconds.

       -C --no-color --no-colour
              Start htop in monochrome mode

       -F --filter=FILTER
              Filter  processes  by terms matching the commands. The terms are matched case-insensi‐
              tive and as fixed strings (not regexs). You can separate multiple terms with "|".

       -h --help
              Display a help message and exit

       -p --pid=PID,PID...
              Show only the given PIDs

       -s --sort-key COLUMN
              Sort by this column (use --sort-key help for a column list).  This will force  a  list
              view unless you specify -t at the same time.

       -u --user=USERNAME|UID
              Show only the processes of a given user

       -U --no-unicode
              Do not use unicode but ASCII characters for graph meters

       -M --no-mouse
              Disable support of mouse control

       --readonly
              Disable all system and process changing features

       -V --version
              Output version information and exit

       -t --tree
              Show  processes  in tree view. This can be used to force a tree view when requesting a
              sort order with -s.

       -H --highlight-changes=DELAY
              Highlight new and old processes

          --drop-capabilities[=off|basic|strict]
              Linux only; requires libcap support.
              Drop unneeded Linux capabilities.  In strict  mode  features  like  killing,  changing
              process  priorities,  and  reading process delay accounting information will not work,
              due to less capabilities held.

INTERACTIVE COMMANDS
       The following commands are supported while in htop:

       Tab, Shift-Tab
            Select the next / the previous screen tab to display.  You can enable showing the screen
            tab names in the Setup screen (F2).

       Up, Alt-k
            Select (highlight) the previous process in the process list. Scroll the list  if  neces‐
            sary.

       Down, Alt-j
            Select (highlight) the next process in the process list. Scroll the list if necessary.

       Left, Alt-h
            Scroll the process list left.

       Right, Alt-l
            Scroll the process list right.

       PgUp, PgDn
            Scroll the process list up or down one window.

       Home Scroll to the top of the process list and select the first process.

       End  Scroll to the bottom of the process list and select the last process.

       Ctrl-A, ^
            Scroll left to the beginning of the process entry (i.e. beginning of line).

       Ctrl-E, $
            Scroll right to the end of the process entry (i.e. end of line).

       Space
            Tag  or  untag  a process. Commands that can operate on multiple processes, like "kill",
            will then apply over the list of tagged processes, instead of the currently  highlighted
            one.

       c    Tag  the  current  process  and  its  children.  Commands  that  can operate on multiple
            processes, like "kill", will then apply over the list of tagged  processes,  instead  of
            the currently highlighted one.

       U    Untag all processes (remove all tags added with the Space or c keys).

       s    Trace  process system calls: if strace(1) is installed, pressing this key will attach it
            to the currently selected process, presenting a live update of system  calls  issued  by
            the process.

       l    Display  open  files for a process: if lsof(1) is installed, pressing this key will dis‐
            play the list of file descriptors opened by the process.

       w    Display the command line of the selected process in a separate screen, wrapped onto mul‐
            tiple lines as needed.

       x    Display the active file locks of the selected process in a separate screen.

       F1, h, ?
            Go to the help screen

       F2, S
            Go to the setup screen, where you can configure the meters displayed at the top  of  the
            screen,  set  various  display  options,  choose  among  color schemes, and select which
            columns are displayed, in which order.

       F3, /
            Incrementally search the command lines of all the displayed processes. The currently se‐
            lected (highlighted) command will update as you type. While in search mode, pressing  F3
            will cycle through matching occurrences.  Pressing Shift-F3 will cycle backwards.

            Alternatively  the  search  can  be started by simply typing the command you are looking
            for, although for the first character normal key bindings take precedence.

       F4, \
            Incremental process filtering: type in part of a process command line and only processes
            whose names match will be shown. To cancel filtering, enter the Filter option again  and
            press  Esc.   The matching is done case-insensitive. Terms are fixed strings (no regex).
            You can separate multiple terms with "|".

       F5, t
            Tree view: organize processes by parenthood, and layout the relations between them as  a
            tree.  Toggling the key will switch between tree and your previously selected sort view.
            Selecting a sort view will exit tree view.

       F6, <, >
            Selects a field for sorting, also accessible through < and >.  The current sort field is
            indicated by a highlight in the header.

       F7, ]
            Increase the selected process's priority (subtract from 'nice' value).  This can only be
            done by the superuser.

       F8, [
            Decrease the selected process's priority (add to 'nice' value)

       Shift-F7, }
            Increase the selected process's  autogroup  priority  (subtract  from  autogroup  'nice'
            value).  This can only be done by the superuser.

       Shift-F8, {
            Decrease the selected process's autogroup priority (add to autogroup 'nice' value)

       F9, k
            "Kill"  process:  sends  a  signal  which  is  selected  in a menu, to one or a group of
            processes. If processes were tagged, sends the signal to all tagged processes.  If  none
            is tagged, sends to the currently selected process.

       F10, q
            Quit

       I    Invert  the  sort  order:  if  sort order is increasing, switch to decreasing, and vice-
            versa.

       +, -, *
            When in tree view mode, expand or collapse subtree. When a subtree is  collapsed  a  "+"
            sign  shows  to  the left of the process name.  Pressing "*" will expand or collapse all
            children of PIDs without parents, so typically PID 1  (init)  and  PID  2  (kthreadd  on
            Linux, if kernel threads are shown).

       a (on multiprocessor machines)
            Set CPU affinity: mark which CPUs a process is allowed to use.

       u    Show only processes owned by a specified user.

       N    Sort by PID.

       M    Sort by memory usage (top compatibility key).

       P    Sort by processor usage (top compatibility key).

       T    Sort by time (top compatibility key).

       F    "Follow" process: if the sort order causes the currently selected process to move in the
            list,  make  the  selection bar follow it. This is useful for monitoring a process: this
            way, you can keep a process always visible on screen. When a movement key is used, "fol‐
            low" loses effect.

       K    Hide kernel threads: prevent the threads belonging the kernel to  be  displayed  in  the
            process list. (This is a toggle key.)

       H    Hide  user  threads:  on systems that represent them differently than ordinary processes
            (such as recent NPTL-based systems), this can hide threads from userspace  processes  in
            the process list. (This is a toggle key.)

       O    Hide  containerized  processes: prevent processes running in a container from being dis‐
            played in the process list. (This is a toggle key.)

       p    Show full paths to running programs, where applicable. (This is a toggle key.)

       Z    Pause/resume process updates.

       m    Merge exe, comm and cmdline, where applicable. (This is a toggle key.)

       Ctrl-L
            Refresh: redraw screen and recalculate values.

       Numbers
            PID search: type in process ID and the selection highlight will be moved to it.

COLUMNS
       The following columns can display data about each process. A value of '-' in all the rows in‐
       dicates that a column is unsupported on your system, or currently unimplemented in htop.  The
       names below are the ones used in the "Available Columns" section of the setup  screen.  If  a
       different name is shown in htop's main screen, it is shown below in parenthesis.

       Command
            The full command line of the process (i.e. program name and arguments).

            If  the  option 'Merge exe, comm and cmdline in Command' (toggled by the 'm' key) is ac‐
            tive, the executable path (/proc/[pid]/exe) and the command name (/proc/[pid]/comm)  are
            also shown merged with the command line, if available.

            The program basename is highlighted if set in the configuration. Additional highlighting
            can be configured for stale executables (cf. EXE column below).

       COMM The command name of the process obtained from /proc/[pid]/comm, if readable.

            Requires Linux kernel 2.6.33 or newer.

       EXE  The   abbreviated   basename   of   the   executable   of  the  process,  obtained  from
            /proc/[pid]/exe, if readable. htop is able to read  this  file  on  linux  for  ALL  the
            processes only if it has the capability CAP_SYS_PTRACE or root privileges.

            The  basename  is  marked  in red if the executable used to run the process has been re‐
            placed or deleted on disk since the process started. The information is obtained by pro‐
            cessing the contents of /proc/[pid]/exe.

            Furthermore the basename is marked in yellow if any library is reported as  having  been
            replaced  or  deleted  on  disk since it was last loaded. The information is obtained by
            processing the contents of /proc/[pid]/maps.

            When deciding the color the replacement of the main executable always  takes  precedence
            over replacement of any other library. If only the memory map indicates a replacement of
            the  main  executable,  this  will  show  as  if  any other library had been replaced or
            deleted.

            This additional color markup can be configured in the "Display Options" section  of  the
            setup screen.

            Displaying EXE requires CAP_SYS_PTRACE and PTRACE_MODE_READ_FSCRED.

       PID  The process ID.

       STATE (S)
            The state of the process:
               S for sleeping
               I for idle (longer inactivity than sleeping on platforms that distinguish)
               R for running
               D for disk sleep (uninterruptible)
               Z for zombie (waiting for parent to read its exit status)
               T for traced or suspended (e.g by SIGTSTP)
               W for paging

       PPID The parent process ID.

       PGRP The process's group ID.

       SESSION (SID)
            The process's session ID.

       TTY  The controlling terminal of the process.

       TPGID
            The process ID of the foreground process group of the controlling terminal.

       MINFLT
            The number of page faults happening in the main memory.

       CMINFLT
            The number of minor faults for the process's waited-for children (see MINFLT above).

       MAJFLT
            The number of page faults happening out of the main memory.

       CMAJFLT
            The number of major faults for the process's waited-for children (see MAJFLT above).

       UTIME (UTIME+)
            The  user  CPU  time, which is the amount of time the process has spent executing on the
            CPU in user mode (i.e. everything but system calls), measured in clock ticks.

       STIME (STIME+)
            The system CPU time, which is the amount of time the kernel has spent  executing  system
            calls on behalf of the process, measured in clock ticks.

       CUTIME (CUTIME+)
            The children's user CPU time, which is the amount of time the process's waited-for chil‐
            dren have spent executing in user mode (see UTIME above).

       CSTIME (CSTIME+)
            The children's system CPU time, which is the amount of time the kernel has spent execut‐
            ing system calls on behalf of all the process's waited-for children (see STIME above).

       PRIORITY (PRI)
            The kernel's internal priority for the process, usually just its nice value plus twenty.
            Different for real-time processes.

       NICE (NI)
            The nice value of a process, from 19 (low priority) to -20 (high priority). A high value
            means  the  process  is  being nice, letting others have a higher relative priority. The
            usual OS permission restrictions for adjusting priority apply.

       STARTTIME (START)
            The time the process was started.

       PROCESSOR (CPU)
            The ID of the CPU the process last executed on.

       M_VIRT (VIRT)
            The size of the virtual memory of the process.

       M_RESIDENT (RES)
            The resident set size (text + data + stack)  of  the  process  (i.e.  the  size  of  the
            process's used physical memory).

       M_SHARE (SHR)
            The size of the process's shared pages.

       M_TRS (CODE)
            The text resident set size of the process (i.e. the size of the process's executable in‐
            structions).

       M_DRS (DATA)
            The  data resident set size (data + stack) of the process (i.e. the size of anything ex‐
            cept the process's executable instructions).

       M_LRS (LIB)
            The library size of the process.

       M_SWAP (SWAP)
            The size of the process's swapped pages.

       M_PSS (PSS)
            The proportional set size, same as M_RESIDENT but each page is divided by the number  of
            processes sharing it.

       M_M_PSSWP (PSSWP)
            The  proportional  swap share of this mapping, unlike M_SWAP this does not take into ac‐
            count swapped out page of underlying shmem objects.

       ST_UID (UID)
            The user ID of the process owner.

       PERCENT_CPU (CPU%)
            The percentage of the CPU time that the process is currently using.  This is the default
            way to represent CPU usage in Linux. Each process can consume up to 100% which means the
            full capacity of the core it is running on. This is sometimes called "Irix mode" e.g. in
            top(1).

       PERCENT_NORM_CPU (NCPU%)
            The percentage of the CPU time that the process is currently  using  normalized  by  CPU
            count. This is sometimes called "Solaris mode" e.g. in top(1).

       PERCENT_MEM (MEM%)
            The percentage of memory the process is currently using (based on the process's resident
            memory size, see M_RESIDENT above).

       USER The username of the process owner, or the user ID if the name can't be determined.

            On  Linux the username is highlighted if the process has elevated privileges, i.e. if it
            has been started from binaries with file capabilities set or  retained  Linux  capabili‐
            ties, via the ambient set, after switching from the root user.

       TIME (TIME+)
            The  time,  measured  in  clock ticks that the process has spent in user and system time
            (see UTIME, STIME above).

       NLWP The number of Light-Weight Processes (=threads) in the process.

       TGID The thread group ID.

       CTID OpenVZ container ID, a.k.a virtual environment ID.

       VPID OpenVZ process ID.

       VXID VServer process ID.

       RCHAR (RD_CHAR)
            The number of bytes the process has read.

       WCHAR (WR_CHAR)
            The number of bytes the process has written.

       SYSCR (RD_SYSC)
            The number of read(2) syscalls for the process.

       SYSCW (WR_SYSC)
            The number of write(2) syscalls for the process.

       RBYTES (IO_RBYTES)
            Bytes of read(2) I/O for the process.

       WBYTES (IO_WBYTES)
            Bytes of write(2) I/O for the process.

       CNCLWB (IO_CANCEL)
            Bytes of cancelled write(2) I/O.

       IO_READ_RATE (DISK READ)
            The I/O rate of read(2) in bytes per second, for the process.

       IO_WRITE_RATE (DISK WRITE)
            The I/O rate of write(2) in bytes per second, for the process.

       IO_RATE (DISK R/W)
            The I/O rate, IO_READ_RATE + IO_WRITE_RATE (see above).

       CGROUP
            Which cgroup the process is in. For a shortened view see the CCGROUP column below.

       CCGROUP
            Shortened view of the cgroup name that the process is in.  This performs  some  pattern-
            based replacements to shorten the displayed string and thus condense the information.
               /*.slice is shortened to /[*] (exceptions below)
               /system.slice is shortened to /[S]
               /user.slice is shortened to /[U]
               /user-*.slice is shortened to /[U:*] (directly preceding /[U] before dropped)
               /machine.slice is shortened to /[M]
               /machine-*.scope  is shortened to /[SNC:*] (SNC: systemd nspawn container), uppercase
            for the monitor
               /lxc.monitor.* is shortened to /[LXC:*]
               /lxc.payload.* is shortened to /[lxc:*]
               /*.scope is shortened to /!*
               /*.service is shortened to /* (suffix removed)

            Encountered escape sequences (e.g. from systemd) inside the cgroup name are not decoded.

       OOM  OOM killer score.

       CTXT Incremental sum of voluntary and nonvoluntary context switches.

       IO_PRIORITY (IO)
            The I/O scheduling class followed by the priority if the class supports it:
               R for Realtime
               B for Best-effort
               id for Idle

       PERCENT_CPU_DELAY (CPUD%)
            The percentage of time spent waiting for a CPU (while runnable). Requires CAP_NET_ADMIN.

       PERCENT_IO_DELAY (IOD%)
            The percentage of time spent waiting for the completion of synchronous  block  I/O.  Re‐
            quires CAP_NET_ADMIN.

       PERCENT_SWAP_DELAY (SWAPD%)
            The percentage of time spent swapping in pages. Requires CAP_NET_ADMIN.

       AGRP The autogroup identifier for the process. Requires Linux CFS to be enabled.

       ANI  The autogroup nice value for the process autogroup. Requires Linux CFS to be enabled.

       All other flags
            Currently unsupported (always displays '-').

EXTERNAL LIBRARIES
       While  htop  depends  on most of the libraries it uses at build time there are two noteworthy
       exceptions to this rule. These exceptions both relate to data displayed in  meters  displayed
       in  the  header  of  htop and were intentionally created as optional runtime dependencies in‐
       stead.  These exceptions are described below:

       libsystemd
              The bindings for libsystemd are used in the SystemD meter to determine the  number  of
              active  services  and the overall system state. Looking for the functions to determine
              these information at runtime allows for builds to support these meters without forcing
              the package manager to install these libraries on systems  that  otherwise  don't  use
              systemd.

              Summary:  no  build time dependency, optional runtime dependency on libsystemd via dy‐
              namic loading, with systemctl(1) fallback.

       libsensors
              The bindings for libsensors are used for the CPU temperature readings in the CPU usage
              meters if displaying the temperature is enabled through the setup screen. In order for
              htop to show these temperatures correctly though, a proper configuration of libsensors
              through its usual configuration files is assumed and that all CPU cores correspond  to
              temperature sensors from the coretemp driver with core 0 corresponding to a sensor la‐
              belled "Core 0". The package temperature may be given as "Package id 0". If missing it
              is inferred as the maximum value from the available per-core readings.

              Summary:  build  time dependency on libsensors(3) C header files, optional runtime de‐
              pendency on libsensors(3) via dynamic loading.

CONFIG FILES
       By default htop reads its configuration from the  XDG-compliant  path  ~/.config/htop/htoprc.
       The  configuration  file is overwritten upon clean exit by htop's in-program Setup configura‐
       tion, so it should not be hand-edited.  If no user configuration exists htop  tries  to  read
       the  system-wide  configuration from /etc/htoprc and as a last resort, falls back to its hard
       coded defaults.

       You may override the location of the configuration file using the $HTOPRC  environment  vari‐
       able (so you can have multiple configurations for different machines that share the same home
       directory, for example).

       The  pcp-htop  utility makes use of htoprc in exactly the same way.  In addition, it supports
       additional configuration files allowing new meters and columns to be added to the display via
       the usual Setup function, which will display additional Available Meters and Available Column
       entries for each runtime configured meter or column.

       These pcp-htop configuration files are read once at startup.  The format of  these  files  is
       described in detail in the pcp-htop(5) manual page.

       This functionality makes available many thousands of Performance Co-Pilot metrics for display
       by pcp-htop, as well as the ability to display custom metrics added at individual sites.  Ap‐
       plications  and services instrumented using the OpenMetrics format https://openmetrics.io can
       also be displayed by pcp-htop if the pmdaopenmetrics(1) component is configured.

       The configuration for both htop and pcp-htop is only saved when a clean  exit  is  performed.
       Sending any signal will cause all configuration changes to be lost.

MEMORY SIZES
       Memory  sizes in htop are displayed in a human-readable form.  Sizes are printed in powers of
       1024 using binary IEC units.  If no suffix is shown the units are  implicitly  K  as  in  KiB
       (kibibyte, 1 KiB = 1024 bytes).

       The  decision to use this convention was made in order to conserve screen space and make mem‐
       ory size representations consistent throughout htop as allocations are granular to full  mem‐
       ory pages (4 KiB for most platforms).

SEE ALSO
       proc(5), top(1), free(1), ps(1), uptime(1) and limits.conf(5).

SEE ALSO FOR PCP
       pmdaopenmetrics(1), PCPIntro(1), PMAPI(3), and pcp-htop(5).

AUTHORS
       htop was originally developed by Hisham Muhammad.  Nowadays it is maintained by the community
       at <htop AT groups.io>.

       pcp-htop  is  maintained  as a collaboration between the <htop AT groups.io> and <pcp AT groups.io>
       communities, and forms part of the Performance Co-Pilot suite of tools.

COPYRIGHT
       Copyright © 2004-2019 Hisham Muhammad.
       Copyright © 2020-2024 htop dev team.

       License GPLv2+: GNU General Public License version 2 or, at your option, any later version.

       This is free software: you are free to change and redistribute it.  There is NO WARRANTY,  to
       the extent permitted by law.

htop 3.3.0                                      2024                                         HTOP(1)
htop(1)
NAME SYNOPSIS DESCRIPTION COMMAND-LINE OPTIONS
-d --delay=DELAY -C --no-color --no-colour -F --filter=FILTER -h --help -p --pid=PID,PID... -s --sort-key COLUMN -u --user=USERNAME|UID -U --no-unicode -M --no-mouse --readonly -V --version -t --tree -H --highlight-changes=DELAY
INTERACTIVE COMMANDS
Tab, Shift-Tab Up, Alt-k Down, Alt-j Left, Alt-h Right, Alt-l PgUp, PgDn Ctrl-A, ^ Ctrl-E, $ Space F1, h, ? F2, S F3, / F4, \ F5, t F6, F7, ] F8, [ Shift-F7, } Shift-F8, { F9, k F10, q a (on multiprocessor machines) Ctrl-L Numbers
COLUMNS
Command STATE (S) SESSION (SID) UTIME (UTIME+) STIME (STIME+) CUTIME (CUTIME+) CSTIME (CSTIME+) PRIORITY (PRI) NICE (NI) STARTTIME (START) PROCESSOR (CPU) M_VIRT (VIRT) M_RESIDENT (RES) M_SHARE (SHR) M_TRS (CODE) M_DRS (DATA) M_LRS (LIB) M_SWAP (SWAP) M_PSS (PSS) M_M_PSSWP (PSSWP) ST_UID (UID) PERCENT_CPU (CPU%) PERCENT_NORM_CPU (NCPU%) PERCENT_MEM (MEM%) TIME (TIME+) RCHAR (RD_CHAR) WCHAR (WR_CHAR) SYSCR (RD_SYSC) SYSCW (WR_SYSC) RBYTES (IO_RBYTES) WBYTES (IO_WBYTES) CNCLWB (IO_CANCEL) IO_READ_RATE (DISK READ) IO_WRITE_RATE (DISK WRITE) IO_RATE (DISK R/W) IO_PRIORITY (IO) PERCENT_CPU_DELAY (CPUD%) PERCENT_IO_DELAY (IOD%) PERCENT_SWAP_DELAY (SWAPD%) All other flags
EXTERNAL LIBRARIES
libsystemd libsensors
CONFIG FILES MEMORY SIZES SEE ALSO SEE ALSO FOR PCP AUTHORS COPYRIGHT

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