iotop.8

.TH IOTOP "8" "January 22, 2024"
.SH NAME
iotop \- simple top\-like I/O monitor
.SH SYNOPSIS
.B iotop
[\fIOPTIONS\fR]
.SH DESCRIPTION
\fBiotop\fR watches I/O usage information available in the Linux kernel
(requires 2.6.20 or later) and displays a table of current I/O usage by
processes or threads on the system. At least the CONFIG_TASK_DELAY_ACCT,
CONFIG_TASK_IO_ACCOUNTING, CONFIG_TASKSTATS and CONFIG_VM_EVENT_COUNTERS
options need to be enabled in your Linux kernel build configuration.
.PP
Running \fBiotop\fR as non\-root user is possible by adding the NET_ADMIN
capability. This can be done by e.g.:
.RS

.B
$ sudo setcap 'cap_net_admin+eip' <path\-to>/iotop

.RE
Be warned that this will also allow other users to run it and get access to
information that normally should not be available to them.
.PP
\fBiotop\fR displays columns for the I/O bandwidth read and written by each
process/thread during the sampling period. It also displays the percentage
of time the thread/process spent while swapping in and while waiting on I/O.
For each process, its I/O priority (class/level) is shown.
.PP
In addition, the total I/O bandwidth read and written during the sampling
period are displayed at the top of the interface.
\fBTotal DISK READ\fR and \fBTotal DISK WRITE\fR values represent total read
and write bandwidth between processes and kernel threads on one side and
kernel block device subsystem on the other. While \fBCurrent DISK READ\fR and
\fBCurrent DISK WRITE\fR values represent corresponding bandwidths for current
disk I/O between the kernel block device subsystem and the underlying hardware
(HDD, SSD, etc.). Thus \fBTotal\fR and \fBCurrent\fR values may not be equal at
any given moment of time due to data caching and I/O operations reordering that
take place inside the Linux kernel.
.PP
Use the \fBleft\fR and \fBright\fR arrows to select the sort column, \fBr\fR or
\fBspace\fR to reverse the sorting order, \fBo\fR to toggle the \fB\-\-only\fR
option (this uses the visible values from the \fBGRAPH\fR column or the
\fBIO\fR column in case the \fBGRAPH\fR column is hidden), \fBp\fR to toggle
the \fB\-\-processes\fR option, \fBa\fR to cycle between the
\fB\-\-accumulated\fR, \fB\-\-accum\-bw\fR and normal operation,
\fBi\fR to change the priority of a thread or a process's thread,
\fBf\fR to change filtering by \fBUID\fR/\fBPID\fR (\fB\-\-user\fR and
\fB\-\-pid\fR options), \fB1\-9\fR to toggle the visibility of the respective
column, \fB0\fR to show all columns, \fBup\fR/\fBdown\fR arrows,
\fBpage\-up\fR/\fBpage\-down\fR/\fBhome\fR/\fBend\fR keys to scroll and \fBq\fR
to quit. Any unrecognized key will be ignored.
.PP
All processes or threads that have exited are displayed grayed for the same time
as is visible in the \fBGRAPH\fR column or 3 seconds when it is hidden. The
invalid data points in the \fBGRAPHS\fR column are displayed inverse or with
letter \fBx\fR (see option \fB\-\-dead\-x\fR and \fBx\fR shortcut). When using
unicode characters each position contains two datapoints and only the positions
with two invalid data points are reversed.
.PP
It is possible for threads of a process to have different priority from their
main process. This is shown with \fB!\fR in the \fBPRIO\fR column of the main
process as e.g. \fB!be/4\fR.
.PP
Threads activity is always aggregated with and shown inside the main process.
.PP
When showing threads, they always appear below their main process and are sorted
in the same way as the processes.
.PP
There are two ways to change the IO priority of a process or thread \- press
\fBi\fR and use arrows to select the process or thread from the visible ones on
screen or press \fBi\fR and type its TID (PID and TID have the same value for
the main process). Then use \fBtab\fR and arrows to change the priority value
and confirm with \fBenter\fR. Shortcuts \fBesc\fR or \fBq\fR will cancel this
mode.
.PP
To change the UID and PID filters, press \fBf\fR and use \fBtab\fR to select the
UID or PID field, then type the numerical id or \fBn\fR to remove the filter and
confirm with \fBenter\fR. Filtering is always done by \fBTID\fR because it is
unique. Note that for the main process PID is the same as TID. Shortcuts
\fBesc\fR or \fBq\fR will cancel this mode.
.PP
Starting with Linux kernel 5.14.x task_delayacct is configurable at runtime and
set to off by default. This setting can be changed in interactive mode by the
\fBCtrl\-T\fR shortcut. In batch mode a warning is printed when the setting is
OFF. From the command line this can be enabled by:
.RS

.B
$ sudo sysctl kernel.task_delayacct=1

.RE
and disabled again by:
.RS

.B
$ sudo sysctl kernel.task_delayacct=0

.RE
It is advisable to keep this option off when not using this or another
monitoring program because when enabled it has some effect on system
performance.
.SH OPTIONS
.TP
\fB\-v\fR, \fB\-\-version\fR
Show the version number and exit
.TP
\fB\-h\fR, \fB\-\-help\fR
Show usage information and exit
.TP
\fB\-H\fR, \fB\-\-help\-type\fR=\fITYPE\fR
Set the type of interactive help shown. Accepted values for \fITYPE\fR are
\fBnone\fR, \fBwin\fR and \fBinline\fR.
.TP
\fB\-o\fR, \fB\-\-only\fR
Only show processes or threads actually doing I/O, instead of showing all
processes or threads. This can be dynamically toggled by pressing \fBo\fR
.TP
\fB\-\-no\-only\fR
Show all processes or threads
.TP
\fB\-b\fR, \fB\-\-batch\fR
Turn on non\-interactive mode.
Useful for logging I/O usage over time
.TP
\fB\-n\fR \fINUM\fR, \fB\-\-iter\fR=\fINUM\fR
Set the number of iterations before quitting (never quit by default).
This is most useful in non\-interactive mode
.TP
\fB\-d\fR \fISEC\fR, \fB\-\-delay\fR=\fISEC\fR
Set the delay between iterations in seconds (1 second by default).
Accepts non\-integer values such as 1.1 seconds
.TP
\fB\-p\fR \fIPID\fR, \fB\-\-pid\fR=\fIPID\fR
A process/thread id to monitor (all by default)
.TP
\fB\-u\fR \fIUSER\fR, \fB\-\-user\fR=\fIUSER\fR
A user id to monitor (all by default).
The value will always be resolved first unless it is prefixed by \fB+\fR in
which case it is treated as numeric only. Values that do not resolve but appear
to be numeric are used as numeric
.TP
\fB\-P\fR, \fB\-\-processes\fR
Only show processes. Normally \fBiotop\fR shows processes and all threads
.TP
\fB\-\-no\-processes\fR
Show processes and all threads
.TP
\fB\-a\fR, \fB\-\-accumulated\fR
Show accumulated I/O instead of bandwidth. In this mode, \fBiotop\fR shows the
amount of I/O processes have done since the process or \fBiotop\fR started.
Note that this option and \-\-accum\-bw are exclusive and they will turn each
other off
.TP
\fB\-\-no\-accumulated\fR
Show bandwidth (useful when changing config file with \fB\-\-write\fR)
.TP
\fB\-A\fR, \fB\-\-accum-bw\fR
Show accumulated I/O as bandwidth for the whole sampling period. In this mode,
\fBiotop\fR shows the amount of I/O per second for the whole period since the
process or \fBiotop\fR started
Note that this option and \-\-accumulated are exclusive and they will turn each
other off
.TP
\fB\-\-no\-accum-bw\fR
Show bandwidth (useful when changing config file with \fB\-\-write\fR)
.TP
\fB\-k\fR, \fB\-\-kilobytes\fR
Use kilobytes instead of a human friendly unit.
This mode is useful when scripting the batch mode of \fBiotop\fR. Instead of
choosing the most appropriate unit \fBiotop\fR will display all sizes in
kilobytes
.TP
\fB\-\-no\-kilobytes\fR
Use human friendly units
.TP
\fB\-t\fR, \fB\-\-time\fR
Add a timestamp on each line (implies \-\-batch). Each line will be prefixed by
the current time
.TP
\fB\-c\fR, \fB\-\-fullcmdline\fR
Show processes' full file path and parameters
.TP
\fB\-\-no\-fullcmdline\fR
Show processes' names only
.TP
\fB\-1\fR, \fB\-\-hide\-pid\fR
Hide PID/TID column
.TP
\fB\-\-show\-pid\fR
Show PID/TID column
.TP
\fB\-2\fR, \fB\-\-hide\-prio\fR
Hide PRIO column
.TP
\fB\-\-show\-prio\fR
Show PRIO column
.TP
\fB\-3\fR, \fB\-\-hide\-user\fR
Hide USER column
.TP
\fB\-\-show\-user\fR
Show USER column
.TP
\fB\-4\fR, \fB\-\-hide\-read\fR
Hide DISK READ column
.TP
\fB\-\-show\-read\fR
Show DISK READ column
.TP
\fB\-5\fR, \fB\-\-hide\-write\fR
Hide DISK WRITE column
.TP
\fB\-\-show\-write\fR
Show DISK WRITE column
.TP
\fB\-6\fR, \fB\-\-hide\-swapin\fR
Hide SWAPIN column
.TP
\fB\-\-show\-swapin\fR
Show SWAPIN column
.TP
\fB\-7\fR, \fB\-\-hide\-io\fR
Hide IO column
.TP
\fB\-\-show\-io\fR
Show IO column
.TP
\fB\-8\fR, \fB\-\-hide\-graph\fR
Hide GRAPH column
.TP
\fB\-\-show\-graph\fR
Show GRAPH column
.TP
\fB\-9\fR, \fB\-\-hide\-command\fR
Hide COMMAND column
.TP
\fB\-\-show\-command\fR
Show COMMAND column
.TP
\fB\-g\fR \fITYPE\fR, \fB\-\-grtype\fR=\fITYPE\fR
Set GRAPH column data source. Accepted values for \fITYPE\fR are \fBio\fR,
\fBr\fR, \fBw\fR, \fBrw\fR and \fBsw\fR.
.TP
\fB\-R\fR, \fB\-\-reverse\-graph\fR
Reverse GRAPH direction \- show most recent values on the right side
.TP
\fB\-\-no\-reverse\-graph\fR
Do not reverse GRAPH direction \- show most recent values on the left side
.TP
\fB\-q\fR, \fB\-\-quiet\fR
Suppress some lines of header (implies \-\-batch). This option can be specified
up to three times to remove header lines
.RS
.PD 0
.TP
.B \-q
column names are only printed on the first iteration,
.TP
.B \-qq
column names are never printed,
.TP
.B \-qqq
the I/O summary is never printed
.RE
.PD 1
.TP
\fB\-x\fR, \fB\-\-dead\-x\fR
Show exited processes/threads with letter x instead of inverse background
.TP
\fB\-\-no\-dead\-x\fR
Show exited processes/threads with inverse background
.TP
\fB\-e\fR, \fB\-\-hide\-exited\fR
Hide exited processes
.TP
\fB\-\-show\-exited\fR
Show exited processes
.TP
\fB\-l\fR, \fB\-\-no\-color\fR
Do not colorize values
.TP
\fB\-\-color\fR
Colorize values. This will override the effect of the environment variable
\fBNO_COLOR\fR when explicitly specified on the command line.
.TP
\fB\-T\fR, \fB\-\-hide\-time\fR
Do not show time clock in upper right corner
.TP
\fB\-\-show\-time\fR
Show time clock in upper right corner
.TP
\fB\-\-si\fR
Use SI units of \fB1000\fR when printing values. The default is non\-SI
\fB1024\fR
.TP
\fB\-\-no\-si\fR
Use non-SI units of \fB1024\fR when printing values
.TP
\fB\-\-threshold=1..10\fR
Set the threshold to switch to next unit. The default value is \fB2\fR
.TP
\fB\-\-ascii\fR
Disable using Unicode
.TP
\fB\-\-unicode\fR
Use Unicode drawing chars
.TP
\fB\-W\fR, \fB\-\-write\fR
Merge the preceding options to the current config, save the config and exit.
Note that all options after this one will be ignored.
.PD 1
.SH KEYBOARD SHORTCUTS
.TP
\fBq\fR, \fBQ\fR
Exit
.TP
\fBW\fR
Save current settings to configuration file in a place conforming to XDG Base
Directory Specification. The respective path is created in case it does not
exist. In case of error creating or accessing the config file, the error is
silently ignored and the configuration is not saved.

.RS
\fB$XDG_CONFIG_HOME/iotop/iotoprc\fR - if environment variable XDG_CONFIG_HOME
is set.
.RE

.RS
\fB$HOME/.config/iotop/iotoprc\fR - if environment variable XDG_CONFIG_HOME is
not set but HOME is set.
.RE

.RS
\fB.config/iotop/iotoprc\fR - if neither XDG_CONFIG_HOME nor HOME are set.
.RE
.TP
\fBD\fR
Reset all settings to their default values
.TP
\fB<space>\fR, \fBr\fR
Toggle sort order
.TP
\fB<home>\fR
Scroll to the top of the list
.TP
\fB<end>\fR
Scroll to the bottom of the list
.TP
\fB<page\-up>\fR
Scroll one screen up
.TP
\fB<page\-down>\fR
Scroll one screen down
.TP
\fB<up>\fR
Scroll one line up
.TP
\fB<down>\fR
Scroll one line down
.TP
\fB<right>\fR
Sort by next column
.TP
\fB<left>\fR
Sort by previous column
.TP
\fB<esc>\fR
Cancel ionice or filter selection. In case only the help window is open then
close it
.TP
\fBo\fR, \fBO\fR
Toggle showing only processes with IO activity
.TP
\fBp\fR, \fBP\fR
Toggle showing processes/threads
.TP
\fBa\fR, \fBA\fR
Cycle showing accumulated/accum-bw/current values
.TP
\fB?\fR
Toggle showing inline help
.TP
\fBh\fR, \fBH\fR
Toggle showing window help
.TP
\fBc\fR, \fBC\fR
Toggle showing full command line
.TP
\fB1\fR, \fB2\fR, \fB3\fR, \fB4\fR, \fB5\fR, \fB6\fR, \fB7\fR, \fB8\fR, \fB9\fR
Toggle showing the column (column number corresponds to the shortcut)
.TP
\fB0\fR
Show all columns
.TP
\fBg\fR, \fBG\fR
Cycle GRAPH source (\fBIO\fR=IO, \fBR\fR=DISK READ , \fBW\fR=DISK WRITE,
\fBR+W\fR=DISK READ+DISK WRITE, \fBSW\fR=SWAPIN). Using \fBg\fR will cycle
forward and \fBG\fR will cycle backward.
.TP
\fBR\fR
Toggle reverse GRAPH direction
.TP
\fBi\fR, \fBI\fR
IOnice a process/thread (depends on process/thread display mode)
.TP
\fBf\fR, \fBF\fR
Change UID and PID filters
.TP
\fBu\fR, \fBU\fR
Toggle using Unicode/ASCII characters for pseudo graph
.TP
\fBl\fR, \fBL\fR
Toggle colorizing values
.TP
\fBx\fR, \fBX\fR
Toggle the display mode of exited processes/threads between letter x and inverse
background
.TP
\fBe\fR, \fBE\fR
Toggle the display of exited processes
.TP
\fBT\fR
Toggle the display of time clock in upper right corner
.TP
\fBs\fR, \fBS\fR
Toggle freeze of data collection
.TP
\fBCtrl\-B\fR, \fBb\fR
Toggle SI units
.TP
\fBCtrl\-R\fR, \fBt\fR
Cycle unit threshold
.TP
\fBCtrl\-T\fR
Toggle task_delayacct kernel sysctl
.TP
\fBCtrl\-L\fR
Redraw screen
.TP
\fB/\fR
Change search regular expression. While the search regular expression is being
edited, there is an indicator next to it that shows if the expression is valid.
The search is confirmed by \fB<enter>\fR or cancelled by \fB<esc>\fR.

\fBList of shortcuts in the editor:\fR
.RS
.TP
\fB<esc>\fR
Cancel editing and remove the regular expression filter
.TP
\fB<enter>\fR
Confirm the current regular expression and exit edit mode. In case the regular
expression is empty or invalid it will match everything.
.TP
\fBAlt/Meta\-<backspace>\fR, \fBCtrl\-W\fR
Delete one word from cursor to the left
.TP
\fBAlt/Meta\-D\fR
Delete one word from cursor to the right
.TP
\fBAlt/Meta\-B\fR, \fBCtrl\-<left>\fR
Move the cursor to the beginning of the word on the left
.TP
\fBAlt/Meta\-F\fR, \fBCtrl\-<right>\fR
Move the cursor after the end of the word on the right
.TP
\fBCtrl\-A\fR, \fB<home>\fR
Move the cursor to the leftmost position
.TP
\fBCtrl\-E\fR, \fB<end>\fR
Move the cursor after the last character
.TP
\fBCtrl\-B\fR, \fB<left>\fR
Move the cursor to the left
.TP
\fBCtrl\-F\fR, \fB<right>\fR
Move the cursor to the right
.TP
\fBCtrl\-H\fR, \fB<backspace>\fR
Delete the character left of cursor
.TP
\fBCtrl\-D\fR, \fB<del>\fR
Delete the character under the cursor
.TP
\fBCtrl\-K\fR
Delete from the character under the cursor to the end of the line
.TP
\fBCtrl\-U\fR
Delete everything
.TP
\fB[anything\-else]\fR
Non-printable characters are ignored. Normal characters are inserted before
the character under the cursor. UTF-8 sequences are parsed and treated
as a single character. Unicode combining characters will be appended to the
character under the cursor.
.RE
.SH ENVIRONMENT
As per the recommendation of \fBhttps://www.no\-color.org/\fR iotop honors the
contents of the environment variable \fBNO_COLOR\fR and when it is set to a non
empty string, all color output is suppressed.
.SH SEE ALSO
.BR ionice (1),
.BR top (1),
.BR vmstat (1),
.BR atop (1),
.BR htop (1)
.SH AUTHOR
The original Python iotop implementation was written by Guillaume Chazarain.
This rewrite in C was started in 2014 by Vyacheslav Trushkin and reworked to
include all missing features from the original Python code and several new ones
from 2020 to 2024 by Boian Bonev.
.PP
This manual page was started by Paul Wise for the Debian project and is placed
in the public domain.