HTOP(1) Utils HTOP(1)
htop - interactive process viewer
Htop is a free (GPL) ncurses-based process viewer for Linux.
It is similar to top, but allows you to scroll vertically and horizon-
tally, so you can see all the processes running on the system, along
with their full command lines, as well as viewing them as a process
tree, selecting multiple processes and acting on them all at once.
Tasks related to processes (killing, renicing) can be done without
entering their PIDs.
Mandatory arguments to long options are mandatory for short options
Delay between updates, in tenths of seconds
-C --no-color --no-colour
Start htop in monochrome mode
Display a help message and exit
Show only the given PIDs
-s --sort-key COLUMN
Sort by this column (use --sort-key help for a column list)
Show only the processes of a given user
Output version information and exit
The following commands are supported while in htop:
Arrows, PgUP, PgDn, Home, End
Scroll the process list.
Tag or untag a process. Commands that can operate on multiple pro-
cesses, like "kill", will then apply over the list of tagged pro-
cesses, instead of the currently highlighted one.
U Untag all processes (remove all tags added with the Space key).
s Trace process system calls: if strace(1) is installed, pressing
this key will attach it to the currently selected process, pre-
senting a live update of system calls issued by the process.
l Display open files for a process: if lsof(1) is installed, press-
ing this key will display the list of file descriptors opened by
F1, h, ?
Go to the help screen
Go to the setup screen, where you can configure the meters dis-
played at the top of the screen, set various display options,
choose among color schemes, and select which columns are dis-
played, in which order.
Incrementally search the command lines of all the displayed pro-
cesses. The currently selected (highlighted) command will update
as you type. While in search mode, pressing F3 will cycle through
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.
Tree view: organize processes by parenthood, and layout the rela-
tions 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 On sorted view, select a field for sorting, also accessible
through < and >. The current sort field is indicated by a high-
light in the header. On tree view, expand or collapse the current
subtree. A "+" indicator in the tree node indicates that it is
Increase the selected process's priority (subtract from 'nice'
value). This can only be done by the superuser.
Decrease the selected process's priority (add to 'nice' value)
"Kill" process: sends a signal which is selected in a menu, to one
or a group of processes. If processes were tagged, sends the sig-
nal to all tagged processes. If none is tagged, sends to the cur-
rently selected process.
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.
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.
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.)
p Show full paths to running programs, where applicable. (This is a
Refresh: redraw screen and recalculate values.
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 sys-
tem, or currently unimplemented in htop. The names below are the ones
used in the "Available Columns" section of the setup screen. If a dif-
ferent name is shown in htop's main screen, it is shown below in paren-
The full command line of the process (i.e. program name and argu-
PID The process ID.
The state of the process:
S for sleeping (idle)
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.
The process's session ID.
The controlling terminal of the process.
The process ID of the foreground process group of the controlling
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).
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 sys-
tem calls), measured in clock ticks.
The system CPU time, which is the amount of time the kernel has
spent executing system calls on behalf of the process, measured in
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 processes.
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.
The time the process was started.
The ID of the CPU the process last executed on.
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).
The size of the process's shared pages.
The text resident set size of the process (i.e. the size of the
process's executable instructions).
The data resident set size (data + stack) of the process (i.e. the
size of anything except the process's executable instructions).
The library size of the process.
The size of the dirty pages of the process.
The user ID of the process owner.
The percentage of the CPU time that the process is currently
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.
The time, measured in clock ticks that the process has spent in
user and system time (see UTIME, STIME above).
NLWP The number of 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.
The number of bytes the process has read.
The number of bytes the process has written.
The number of read(2) syscalls for the process.
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.
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).
Which cgroup the process is in.
OOM OOM killer score.
The I/O scheduling class followed by the priority if the class
R for Realtime
B for Best-effort
id for Idle
All other flags
Currently unsupported (always displays '-').
By default htop reads its configuration from the XDG-compliant path
~/.config/htop/htoprc -- the configuration file is overwritten 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 con-
figuration 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 $HTO-
PRC environment variable (so you can have multiple configurations for
different machines that share the same home directory, for example).
Memory sizes in htop are displayed as they are in tools from the GNU
Coreutils (when ran with the --human-readable option). This means that
sizes are printed in powers of 1024. (e.g., 1023M = 1072693248 Bytes)
The decision to use this convention was made in order to conserve
screen space and make memory size representations consistent throughout
proc(5), top(1), free(1), ps(1), uptime(1), limits.conf(5)
htop is developed by Hisham Muhammad <firstname.lastname@example.org>.
This man page was written by Bartosz Fenski <email@example.com> for the
Debian GNU/Linux distribution (but it may be used by others). It was
updated by Hisham Muhammad, and later by Vincent Launchbury, who wrote
the 'Columns' section.
htop 2.0.1 2015 HTOP(1)
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