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NAME | SYNOPSIS | DESCRIPTION | COMMAND-LINE OPTIONS | INTERACTIVE COMMANDS | COLUMNS | EXTERNAL LIBRARIES | CONFIG FILES | MEMORY SIZES | SEE ALSO | SEE ALSO FOR PCP | AUTHORS | COPYRIGHT | COLOPHON |
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HTOP(1) User Commands HTOP(1)
htop, pcp-htop - interactive process viewer
htop [-dCFhpustvH]
pcp-htop [-dCFhpustvH] [--host/-h host]
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
--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; this option needs to have been enabled at
compile-time and requires libcap support at runtime.
Drop unneeded Linux capabilities. In strict mode features
like killing, changing process priorities and reading
process delay accounting information will not work due to
fewer capabilities being 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
(F2).
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
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 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'
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, "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.)
Ctrl-L
Refresh: redraw screen and recalculate values.
Numbers
PID search: type in process ID and the selection highlight
will be moved to it.
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.
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 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).
The Command column should be the last column in each screen
as can get very long and profits from being able to extend
its length dynamically.
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
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 children 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 executing 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 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
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 account 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
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
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. Requires 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 '-').
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 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 dynamic 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 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.
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 a similar way.
However, pcp-htop reads its configuration from a path more
conventionally used by Performance Co-Pilot tools,
~/.pcp/htop/htoprc, in order to provide separate configuration
when both htop and pcp-htop are installed and in use. pcp-htop
supports additional configuration files below the same directory
allowing new meters, columns and screen tabs to be added via the
Setup screen (F2). This displays additional Available Meters,
Available Column and Screen Tabs for each meter, column or screen
configuration file.
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
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 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).
proc(5), top(1), free(1), ps(1), uptime(1) and limits.conf(5).
pmdaopenmetrics(1), PCPIntro(1), PMAPI(3), and pcp-htop(5).
htop was originally developed by Hisham Muhammad. Nowadays it is
maintained by the community at <htop@groups.io>.
pcp-htop is maintained as a collaboration between the
<htop@groups.io> and <pcp@groups.io> communities, and forms part
of the Performance Co-Pilot suite of tools.
Copyright © 2004-2019 Hisham Muhammad.
Copyright © 2020-2025 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.
This page is part of the htop (an interactive process viewer)
project. Information about the project can be found at
⟨http://hisham.hm/htop/⟩. If you have a bug report for this manual
page, see ⟨http://github.com/hishamhm/htop/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/htop-dev/htop⟩ on 2025-02-02. (At that time,
the date of the most recent commit that was found in the
repository was 2025-01-26.) 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
htop 3.4.0-dev-3.3.0-245-gab455a2 2025 HTOP(1)
Pages that refer to this page: proc(5), iotop(8)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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