.TH "HTOP" "1" "2024" "@PACKAGE_STRING@" "User Commands"
.SH "NAME"
htop, pcp-htop \- interactive process viewer
.SH "SYNOPSIS"
.B htop
.RB [ \-dCFhpustvH ]
.br
.B pcp-htop
.RB [ \-dCFhpustvH ]
.RB [ \-\-host/-h\ host ]
.SH "DESCRIPTION"
.B htop
is a cross-platform ncurses-based process viewer.
.LP
It is similar to
.BR 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.
.LP
Tasks related to processes (killing, renicing) can be done without
entering their PIDs.
.LP
.B pcp-htop
is a version of
.B htop
built using the Performance Co-Pilot (PCP) Metrics API (see \c
.BR PCPIntro (1),
.BR PMAPI (3)),
allowing to extend
.B htop
to display values from arbitrary metrics.
See the section below titled
.B "CONFIG FILES"
for further details.
.br
.SH "COMMAND-LINE OPTIONS"
Mandatory arguments to long options are mandatory for short options too.
.TP
\fB\-d \-\-delay=DELAY\fR
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.
.TP
\fB\-C \-\-no-color \-\-no-colour\fR
Start
.B htop
in monochrome mode
.TP
\fB\-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 "|".
.TP
\fB\-h \-\-help
Display a help message and exit
.TP
\fB\-p \-\-pid=PID,PID...\fR
Show only the given PIDs
.TP
\fB\-s \-\-sort\-key COLUMN\fR
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.
.TP
\fB\-u \-\-user=USERNAME|UID\fR
Show only the processes of a given user
.TP
\fB\-U \-\-no-unicode\fR
Do not use unicode but ASCII characters for graph meters
.TP
\fB\-M \-\-no-mouse\fR
Disable support of mouse control
.TP
\fB\-\-readonly\fR
Disable all system and process changing features
.TP
\fB\-V \-\-version
Output version information and exit
.TP
\fB\-t \-\-tree
Show processes in tree view. This can be used to force a tree view when
requesting a sort order with -s.
.TP
\fB\-H \-\-highlight-changes=DELAY\fR
Highlight new and old processes
.TP
\fB\-\-drop-capabilities[=off|basic|strict]\fR
Linux only; this option needs to have been enabled at compile-time and
requires libcap support at runtime.
.br
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.
.SH "INTERACTIVE COMMANDS"
The following commands are supported while in
.BR htop :
.TP 5
.B 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).
.TP
.B Up, Alt-k
Select (highlight) the previous process in the process list. Scroll the list
if necessary.
.TP
.B Down, Alt-j
Select (highlight) the next process in the process list. Scroll the list if
necessary.
.TP
.B Left, Alt-h
Scroll the process list left.
.TP
.B Right, Alt-l
Scroll the process list right.
.TP
.B PgUp, PgDn
Scroll the process list up or down one window.
.TP
.B Home
Scroll to the top of the process list and select the first process.
.TP
.B End
Scroll to the bottom of the process list and select the last process.
.TP
.B Ctrl-A, ^
Scroll left to the beginning of the process entry (i.e. beginning of line).
.TP
.B Ctrl-E, $
Scroll right to the end of the process entry (i.e. end of line).
.TP
.B 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.
.TP
.B 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.
.TP
.B U
Untag all processes (remove all tags added with the Space or c keys).
.TP
.B 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.
.TP
.B 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.
.TP
.B w
Display the command line of the selected process in a separate screen, wrapped
onto multiple lines as needed.
.TP
.B x
Display the active file locks of the selected process in a separate screen.
.TP
.B F1, h, ?
Go to the help screen
.TP
.B 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.
.TP
.B 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.
.TP
.B 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 "|".
.TP
.B 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.
.TP
.B F6, <, >
Selects a field for sorting, also accessible through < and >.
The current sort field is indicated by a highlight in the header.
.TP
.B F7, ]
Increase the selected process's priority (subtract from 'nice' value).
This can only be done by the superuser.
.TP
.B F8, [
Decrease the selected process's priority (add to 'nice' value)
.TP
.B Shift-F7, }
Increase the selected process's autogroup priority (subtract from autogroup 'nice' value).
This can only be done by the superuser.
.TP
.B Shift-F8, {
Decrease the selected process's autogroup priority (add to autogroup 'nice' value)
.TP
.B 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.
.TP
.B F10, q
Quit
.TP
.B I
Invert the sort order: if sort order is increasing, switch to decreasing, and
vice-versa.
.TP
.B +, \-, *
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).
.TP
.B a (on multiprocessor machines)
Set CPU affinity: mark which CPUs a process is allowed to use.
.TP
.B u
Show only processes owned by a specified user.
.TP
.B N
Sort by PID.
.TP
.B M
Sort by memory usage (top compatibility key).
.TP
.B P
Sort by processor usage (top compatibility key).
.TP
.B T
Sort by time (top compatibility key).
.TP
.B 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.
.TP
.B K
Hide kernel threads: prevent the threads belonging the kernel to be
displayed in the process list. (This is a toggle key.)
.TP
.B 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.)
.TP
.B O
Hide containerized processes: prevent processes running in a container
from being displayed in the process list. (This is a toggle key.)
.TP
.B p
Show full paths to running programs, where applicable. (This is a toggle key.)
.TP
.B Z
Pause/resume process updates.
.TP
.B m
Merge exe, comm and cmdline, where applicable. (This is a toggle key.)
.TP
.B Ctrl-L
Refresh: redraw screen and recalculate values.
.TP
.B Numbers
PID search: type in process ID and the selection highlight will be moved to it.
.PD
.SH "COLUMNS"
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
.BR htop .
The names below are the ones used in the
"Available Columns" section of the setup screen. If a different name is
shown in
.BR htop 's
main screen, it is shown below in parenthesis.
.TP 5
.B 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).
.TP
.B COMM
The command name of the process obtained from /proc/[pid]/comm, if readable.

Requires Linux kernel 2.6.33 or newer.
.TP
.B 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.
.TP
.B PID
The process ID.
.TP
.B STATE (S)
The state of the process:
   \fBS\fR for sleeping
   \fBI\fR for idle (longer inactivity than sleeping on platforms that distinguish)
   \fBR\fR for running
   \fBD\fR for disk sleep (uninterruptible)
   \fBZ\fR for zombie (waiting for parent to read its exit status)
   \fBT\fR for traced or suspended (e.g by SIGTSTP)
   \fBW\fR for paging
.TP
.B PPID
The parent process ID.
.TP
.B PGRP
The process's group ID.
.TP
.B SESSION (SID)
The process's session ID.
.TP
.B TTY
The controlling terminal of the process.
.TP
.B TPGID
The process ID of the foreground process group of the controlling terminal.
.TP
.B MINFLT
The number of page faults happening in the main memory.
.TP
.B CMINFLT
The number of minor faults for the process's waited-for children (see MINFLT above).
.TP
.B MAJFLT
The number of page faults happening out of the main memory.
.TP
.B CMAJFLT
The number of major faults for the process's waited-for children (see MAJFLT above).
.TP
.B 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.
.TP
.B 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.
.TP
.B 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).
.TP
.B 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).
.TP
.B PRIORITY (PRI)
The kernel's internal priority for the process, usually just its nice value
plus twenty. Different for real-time processes.
.TP
.B 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.
.TP
.B STARTTIME (START)
The time the process was started.
.TP
.B PROCESSOR (CPU)
The ID of the CPU the process last executed on.
.TP
.B M_VIRT (VIRT)
The size of the virtual memory of the process.
.TP
.B M_RESIDENT (RES)
The resident set size (text + data + stack) of the process (i.e. the size of the
process's used physical memory).
.TP
.B M_SHARE (SHR)
The size of the process's shared pages.
.TP
.B M_TRS (CODE)
The text resident set size of the process (i.e. the size of the process's
executable instructions).
.TP
.B 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).
.TP
.B M_LRS (LIB)
The library size of the process.
.TP
.B M_SWAP (SWAP)
The size of the process's swapped pages.
.TP
.B M_PSS (PSS)
The proportional set size, same as M_RESIDENT but each page is divided by the
number of processes sharing it.
.TP
.B 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.
.TP
.B ST_UID (UID)
The user ID of the process owner.
.TP
.B 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
.BR top (1).
.TP
.B 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
.BR top (1).
.TP
.B PERCENT_MEM (MEM%)
The percentage of memory the process is currently using (based on the process's
resident memory size, see M_RESIDENT above).
.TP
.B 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.
.TP
.B TIME (TIME+)
The time, measured in clock ticks that the process has spent in user and system
time (see UTIME, STIME above).
.TP
.B NLWP
The number of Light-Weight Processes (=threads) in the process.
.TP
.B TGID
The thread group ID.
.TP
.B CTID
OpenVZ container ID, a.k.a virtual environment ID.
.TP
.B VPID
OpenVZ process ID.
.TP
.B VXID
VServer process ID.
.TP
.B RCHAR (RD_CHAR)
The number of bytes the process has read.
.TP
.B WCHAR (WR_CHAR)
The number of bytes the process has written.
.TP
.B SYSCR (RD_SYSC)
The number of read(2) syscalls for the process.
.TP
.B SYSCW (WR_SYSC)
The number of write(2) syscalls for the process.
.TP
.B RBYTES (IO_RBYTES)
Bytes of read(2) I/O for the process.
.TP
.B WBYTES (IO_WBYTES)
Bytes of write(2) I/O for the process.
.TP
.B CNCLWB (IO_CANCEL)
Bytes of cancelled write(2) I/O.
.TP
.B IO_READ_RATE (DISK READ)
The I/O rate of read(2) in bytes per second, for the process.
.TP
.B IO_WRITE_RATE (DISK WRITE)
The I/O rate of write(2) in bytes per second, for the process.
.TP
.B IO_RATE (DISK R/W)
The I/O rate, IO_READ_RATE + IO_WRITE_RATE (see above).
.TP
.B CGROUP
Which cgroup the process is in. For a shortened view see the CCGROUP column below.
.TP
.B 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.
   \fB/*.slice\fR is shortened to \fB/[*]\fR (exceptions below)
   \fB/system.slice\fR is shortened to \fB/[S]\fR
   \fB/user.slice\fR is shortened to \fB/[U]\fR
   \fB/user-*.slice\fR is shortened to \fB/[U:*]\fR (directly preceding \fB/[U]\fR before dropped)
   \fB/machine.slice\fR is shortened to \fB/[M]\fR
   \fB/machine-*.scope\fR is shortened to \fB/[SNC:*]\fR (SNC: systemd nspawn container), uppercase for the monitor
   \fB/lxc.monitor.*\fR is shortened to \fB/[LXC:*]\fR
   \fB/lxc.payload.*\fR is shortened to \fB/[lxc:*]\fR
   \fB/*.scope\fR is shortened to \fB/!*\fR
   \fB/*.service\fR is shortened to \fB/*\fR (suffix removed)

Encountered escape sequences (e.g. from systemd) inside the cgroup name are not decoded.
.TP
.B OOM
OOM killer score.
.TP
.B CTXT
Incremental sum of voluntary and nonvoluntary context switches.
.TP
.B IO_PRIORITY (IO)
The I/O scheduling class followed by the priority if the class supports it:
   \fBR\fR for Realtime
   \fBB\fR for Best-effort
   \fBid\fR for Idle
.TP
.B PERCENT_CPU_DELAY (CPUD%)
The percentage of time spent waiting for a CPU (while runnable). Requires CAP_NET_ADMIN.
.TP
.B PERCENT_IO_DELAY (IOD%)
The percentage of time spent waiting for the completion of synchronous block I/O. Requires CAP_NET_ADMIN.
.TP
.B PERCENT_SWAP_DELAY (SWAPD%)
The percentage of time spent swapping in pages. Requires CAP_NET_ADMIN.
.TP
.B AGRP
The autogroup identifier for the process. Requires Linux CFS to be enabled.
.TP
.B ANI
The autogroup nice value for the process autogroup. Requires Linux CFS to be enabled.
.TP
.B All other flags
Currently unsupported (always displays '-').
.SH "EXTERNAL LIBRARIES"
While
.B 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
.B htop
and were intentionally created as optional runtime dependencies instead.
These exceptions are described below:
.TP
.B 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
.B libsystemd
via dynamic loading, with
.B systemctl(1)
fallback.
.TP
.B 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
.B 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
.B 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
.B libsensors(3)
C header files, optional runtime dependency on
.B libsensors(3)
via dynamic loading.
.SH "CONFIG FILES"
By default
.B htop
reads its configuration from the XDG-compliant path
.IR ~/.config/htop/htoprc .
The configuration file is overwritten upon clean exit by
.BR htop 's
in-program Setup configuration, so it should not be hand-edited.
If no user configuration exists
.B htop
tries to read the system-wide configuration from
.I @sysconfdir@/htoprc
and as a last resort, falls back to its hard coded defaults.
.LP
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).
.LP
The
.B pcp-htop
utility makes use of
.I htoprc
in a similar way.
However,
.B pcp-htop
reads its configuration from a path more conventionally used by
Performance Co-Pilot tools,
.IR ~/.pcp/htop/htoprc ,
in order to provide separate configuration when both
.B htop
and
.B pcp-htop
are installed and in use.
.B 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.
.LP
These
.B pcp-htop
configuration files are read once at startup.
The format of these files is described in detail in the
.BR pcp-htop (5)
manual page.
.LP
This functionality makes available many thousands of Performance
Co-Pilot metrics for display by
.BR pcp-htop ,
as well as the ability to display custom metrics added at individual sites.
Applications and services instrumented using the OpenMetrics format
.B https://openmetrics.io
can also be displayed by
.B pcp-htop
if the
.BR pmdaopenmetrics (1)
component is configured.
.LP
The configuration for both
.B htop
and
.B pcp-htop
is only saved when a clean exit is performed. Sending any signal will cause
.I all configuration changes to be lost.
.SH "MEMORY SIZES"
Memory sizes in
.B 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).
.LP
The decision to use this convention was made in order to conserve screen
space and make memory size representations consistent throughout
.B htop
as allocations are granular to full memory pages (4 KiB for most platforms).
.SH "SEE ALSO"
.BR proc (5),
.BR top (1),
.BR free (1),
.BR ps (1),
.BR uptime (1)
and
.BR limits.conf (5).
.SH "SEE ALSO FOR PCP"
.BR pmdaopenmetrics (1),
.BR PCPIntro (1),
.BR PMAPI (3),
and
.BR pcp-htop (5).
.SH "AUTHORS"
.B htop
was originally developed by Hisham Muhammad.
Nowadays it is maintained by the community at <htop@groups.io>.
.LP
.B 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.
.SH "COPYRIGHT"
Copyright \(co 2004-2019 Hisham Muhammad.
.br
Copyright \(co 2020-2024 htop dev team.
.LP
License GPLv2+: GNU General Public License version 2 or, at your option, any later version.
.LP
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.