htop(1) — Linux manual page


HTOP(1)                       User Commands                      HTOP(1)

NAME         top

       htop, pcp-htop - interactive process viewer

SYNOPSIS         top

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

DESCRIPTION         top

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

       It is similar to top, but allows you to scroll vertically and
       horizontally, and interact using 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.


       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
              decreased 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-insensitive 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

              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

              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.


       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

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

       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

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

       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

            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 display the list of file descriptors
            opened by the process.

       w    Display the command line of the selected process in a
            separate screen, wrapped onto multiple 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 selected (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'

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

       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

       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

       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, "follow" 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 displayed 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.)

            Refresh: redraw screen and recalculate values.

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

COLUMNS         top

       The following columns can display data about each process. A
       value of '-' in all the rows indicates 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.

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

            If the option 'Merge exe, comm and cmdline in Command'
            (toggled by the 'm' key) is active, 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 replaced or deleted on disk since the
            process started. The information is obtained by processing
            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

       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.

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

            The number of page faults happening in the main memory.

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

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

            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.

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

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

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

       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

            The time the process was started.

            The ID of the CPU the process last executed on.

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

            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 instructions).

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

       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 account swapped out page of
            underlying shmem objects.

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

            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).

            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).

            The percentage of memory the process is currently using
            (based on the process's resident memory size, see M_RESIDENT

       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
            capabilities, 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

       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.

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

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

            Bytes of cancelled write(2) I/O.

            The I/O rate of read(2) in bytes per second, for the

            The I/O rate of write(2) in bytes per second, for the

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

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

            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

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

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

            The percentage of time spent waiting for the completion of
            synchronous block I/O. Requires CAP_NET_ADMIN.

            The percentage of time spent swapping in pages. Requires

       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 '-').


       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 instead.  These exceptions are described

              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

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

              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 labelled
              "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 dependency on libsensors(3) via
              dynamic loading.

CONFIG FILES         top

       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
       configuration, so it should not be hand-edited.  If no user
       configuration exists htop tries to read the system-wide
       configuration from ${prefix}/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 variable (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

       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.
       Applications and services instrumented using the OpenMetrics
       format 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         top

       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 memory size representations consistent
       throughout htop as allocations are granular to full memory pages
       (4 KiB for most platforms).

SEE ALSO         top

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

SEE ALSO FOR PCP         top

       pmdaopenmetrics(1), PCPIntro(1), PMAPI(3), and pcp-htop(5).

AUTHORS         top

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

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

COPYRIGHT         top

       Copyright © 2004-2019 Hisham Muhammad.
       Copyright © 2020-2023 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.

COLOPHON         top

       This page is part of the htop (an interactive process viewer)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this
       manual page, see ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2023-12-18.)  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

htop 3.3.0-dev                    2023                           HTOP(1)

Pages that refer to this page: proc(5)iotop(8)