usr.bin/top/top.1

.Dd July 26, 2015
.Dt TOP 1
.Os
.Sh NAME
.Nm top
.Nd display and update information about the top cpu processes
.Sh SYNOPSIS
.Nm
.Op Fl CIMSTabcinqtuv
.Op Fl d Ar count
.Op Fl m Ar mode
.Op Fl o Ar field
.Op Fl s Ar time
.Op Fl U Ar username
.Op Ar number
.Sh DESCRIPTION
.Nm
displays the top
processes on the system and periodically updates this information.
Raw cpu percentage is used to rank the processes.
.Pp
.Nm
makes a distinction between terminals that support advanced capabilities
and those that do not.
This distinction affects the choice of defaults for certain options.
In the remainder of this document, an
.Dq intelligent
terminal is one that
supports cursor addressing, clear screen, and clear to end of line.
Conversely, a
.Dq dumb
terminal is one that does not support such features.
If the output of
.Nm
is redirected to a file, it acts as if it was being run on a dumb
terminal.
.Ss OPTIONS
.Bl -tag -width "-U username" -offset indent
.It Fl C
Turn off the use of color in the display.
.It Fl I
Do not display idle processes.
By default, top displays both active and idle processes.
.It Fl M
Enable multi-CPU display.
.It Fl S
Show system processes in the display.
Normally, system processes such as the pager and the swapper are not shown.
This option makes them visible.
.It Fl T
List all available color tags and the current set of tests used for
color highlighting, then exit.
.It Fl a
Show all processes for as long as possible.
This is shorthand for
.Dq Fl d Li all Li all .
This option is especially handy in batch mode.
.It Fl b
Use
.Dq batch
mode.
In this mode, all input from the terminal is ignored.
Interrupt characters (such as ^C and ^\e) still have an effect.
This is the default on a dumb terminal, or when the output is not a terminal.
.It Fl c
Show the full command line for each process.
Default is to show just the command name.
This option is not supported on all platforms.
.It Fl i
Use
.Dq interactive
mode.
In this mode, any input is immediately read for processing.
See the subsection on
.Sx INTERACTIVE MODE
for an explanation of which keys perform what functions.
After the command is processed, the screen will immediately be updated,
even if the command was not understood.
This mode is the default when standard output is an intelligent terminal.
.It Fl q
Renice
.Nm
to \-20 so that it will run faster.
This can be used when the system is being very sluggish to improve the
possibility of discovering the problem.
This option can only be used by root.
.It Fl t
Show individual threads on separate lines.
By default, on systems which support threading, each process is shown
with a count of the number of threads.
This option shows each thread on a separate line.
This option is not supported on all platforms.
.It Fl u
Do not take the time to map uid numbers to usernames.
Normally,
.Nm
will read as much of the file
.Pa /etc/passwd
as is necessary to map all the user id numbers it encounters into login names.
This option disables all that, while possibly decreasing execution time.
The uid numbers are displayed instead of the names.
.It Fl v
Write version number information to stderr then exit immediately.
No other processing takes place when this option is used.
To see current revision information while top is running,
use the help command
.Dq \&? .
.It Fl d Ar count
Show only
.Ar count
displays, then exit.
A display is considered to be one update of the screen.
This option allows the user to select the number of displays he
wants to see before
.Nm
automatically exits.
Any proper prefix of the words
.Sq Li infinity ,
.Sq Li maximum ,
or
.Sq Li all
can be used to indicate an infinite number of displays.
The default for intelligent terminals is
.Sq Li infinity .
The default for dumb terminals is
.Sq Li 1 .
.It Fl m Ar mode
Start the display in an alternate mode.
Some platforms support multiple
process displays to show additional process information.
The value of
.Ar mode
is a number indicating which mode to display.
The default is
.Sq Li 0 .
On platforms that do not have multiple display modes this option has
no effect.
.It Fl o Ar field
Sort the process display area on the specified field.
The field name is the name of the column as seen in the output,
but in lower case.
Likely values are
.Sq Li cpu ,
.Sq Li size ,
.Sq Li res ,
and
.Sq Li time ,
but may vary on different operating systems.
Note that not all operating systems support this option.
.It Fl s Ar time
Set the delay between screen updates to
.Ar time
seconds.
The default delay between updates is 5 seconds.
.It Fl U Ar username
Show only those processes owned by
.Ar username .
This option currently only accepts usernames and will not understand
uid numbers.
.El
.Pp
If
.Ar number
is given, then the top
.Ar number
processes will be displayed instead of the default.
Both
.Ar count
and
.Ar number
fields can be specified as
.Sq Li infinite ,
indicating that they can stretch as far as possible.
This is accomplished by using any proper prefix of the keywords
.Sq Li infinity ,
.Sq Li maximum ,
or
.Sq Li all .
The default for
.Ar count
on an intelligent terminal is, in fact,
.Sq Li infinity .
.Ss INTERACTIVE MODE
When
.Nm
is running in
.Dq interactive mode ,
it reads commands from the terminal and acts upon them accordingly.
In this mode, the terminal is put in
.Dq CBREAK ,
so that a character will be processed as soon as it is typed.
Almost always, a key will be pressed when
.Nm
is between displays; that is, while it is waiting for
.Ar time
seconds to elapse.
If this is the case, the command will be
processed and the display will be updated immediately thereafter
(reflecting any changes that the command may have specified).
This happens even if the command was incorrect.
If a key is pressed while
.Nm
is in the middle of updating the display, it will finish the update and
then process the command.
Some commands require additional information,
and the user will be prompted accordingly.
While typing this information
in, the user's erase and kill keys (as set up by the command
.Xr stty 1 )
are recognized, and a newline terminates the input.
Note that a control\-L
(^L) always redraws the current screen and a space forces an immediate
update to the screen using new data.
.Pp
These commands are currently recognized:
.Bl -tag -width "h or \&?" -offset indent
.It h or \&?
Display a summary of the commands (help screen).
Version information is included in this display.
.It C
Toggle the use of color in the display.
.It c
Display only processes whose commands match the specified string.
An empty string will display all processes.
This command is not supported on all platforms.
.It d
Change the number of displays to show (prompt for new number).
Remember that the next display counts as one, so typing
.Dq d1
will make
.Nm
show one final display and then immediately exit.
.It f
Toggle the display of the full command line.
.It H
Toggle the display of threads on separate lines.
By default, on systems which support threading,
each process is shown with a count of the number of threads.
This command shows each thread on a separate line.
This command is not supported on all platforms.
.It i or I
Toggle the display of idle processes.
.It k
Send a signal (
.Dq kill
by default) to a list of processes.
This acts similarly to the command
.Xr kill 1 .
.It M
Sort display by memory usage.
Shorthand for
.Dq Fl o Li size .
.It m
Change to a different process display mode.
Some systems provide multiple
display modes for the process display which shows different information.
This command toggles between the available modes.
This command is not supported on all platforms.
.It N
Sort by process id.
Shorthand for
.Dq Fl o Li pid .
.It n or #
Change the number of processes to display (prompt for new number).
.It o
Change the order in which the display is sorted.
This command is not available on all systems.
The sort key names vary fron system to system,
but usually include:
.Sq Li cpu ,
.Sq Li res ,
.Sq Li size ,
and
.Sq Li time .
The default is
.Sq Li cpu .
.It P
Sort by CPU usage.
Shorthand for
.Dq Fl o Li cpu .
.It q
Quit
.Nm .
.It r
Change the priority (the niceness) of a list of processes.
This acts similarly to the command
.Xr renice 8 .
.It s
Change the number of seconds to delay between displays
(prompt for new number).
.It T
Sort by CPU time.
Shorthand for
.Dq Fl o Li time .
.It U
Toggle between displaying usernames and uids.
.It u
Display only processes owned by a specific username (prompt for username).
If the username specified is simply
.Dq + ,
then processes belonging to all users will be displayed.
.El
.Ss THE DISPLAY
The actual display varies depending on the specific variant of Unix
that the machine is running.
This description may not exactly match what is seen by top running on
this particular machine.
Differences are listed at the end of this manual entry.
.Pp
The top lines of the display show general information
about the state of the system.
The first line shows
(on some systems) the last process id assigned to a process,
the three load averages,
the system uptime, and the current time.
The second line displays the total number of processes followed
by a breakdown of processes per state.
Examples of states common
to Unix systems are sleeping, running, starting, stopped, and zombie.
The next line displays a percentage of time spent in each of the
processor states (user, nice, system, interrupt, idle).
These percentages show the processor activity during the time since
the last update.
For multi-processor systems, this information is an average of all processors.
The next line shows kernel-related activity (not available on all systems).
The numbers shown on this line are per-second rates sampled since the last
update.
The exact information displayed varies between systems, but some examples are:
context switches, interrupts, traps, forks, and page faults.
.Pp
The last two lines show a summary of memory and swap activity.
The fields are as follows:
.Bl -tag -width "Active:" -offset indent
.It Active:
number of pages active
.It Inact:
number of pages inactive
.It Wired:
number of pages wired down, including cached file data pages
.It Cache:
number of pages used for VM-level disk caching
.It Buf:
number of pages used for BIO-level disk caching
.It Free:
number of pages free
.It Total:
total available swap usage
.It Free:
total free swap usage
.It Inuse:
swap usage
.It In:
pages paged in from swap devices (last interval)
.It Out:
pages paged out to swap devices (last interval)
.It K:
Kilobyte
.It M:
Megabyte
.It %:
1/100
.El
.Pp
The remainder of the screen displays information about individual
processes.
This display is similar in spirit to
.Xr ps 1 ,
but it is not exactly the same.
The columns displayed by top will differ slightly between operating systems.
Generally, the following fields are displayed:
.Bl -tag -width "USERNAME" -offset indent
.It PID
The process id.
.It USERNAME
Username of the process's owner (if
.Fl u
is specified, a UID column will be substituted for USERNAME).
.It NICE
Nice amount in the range \-20 to 20, as established by the use of
the command
.Xr nice 1 .
.It SIZE
Total size of the process (text, data, and stack) given in kilobytes.
.It RES
Resident memory: current amount of process memory that resides in physical
memory, given in kilobytes, megabytes or gigabytes depending on the size to be reported.
.It STATE
Current state (typically one of
.Sq sleep ,
.Sq run ,
.Sq idl ,
.Sq zomb ,
or
.Sq stop ) .
.It C
Number of CPU the process is currently running on (only on multi-CPU machines).
.It TIME
Number of system and user cpu seconds that the process has used.
.It CTIME
The cumulated CPU time of the process and its exited children.
This value is similar to what
.Xr ps 1
displays as CPU time when run with the
.Fl S
option.
.It CPU
Percentage of available cpu time used by this process.
.It COMMAND
Name of the command that the process is currently running.
.El
.Ss COLOR
Top supports the use of ANSI color in its output.
By default, color is available but not used.
The environment variable
.Ev TOPCOLORS
specifies colors to use and conditions for which they should be used.
At the present time, only numbers in the summary display area can be
colored.
In a future version it will be possible to highlight numbers
in the process display area as well.
The environment variable is the only way to specify color:
there is no equivalent command line option.
Note that the environment variable
.Ev TOPCOLOURS
is also understood.
The British spelling takes precedence.
The use of color only works on terminals that understand and process
ANSI color escape sequences.
.Pp
You can see a list of color codes recognized by this installation of top
with the
.Fl T
option.
This will also show the current set of tests used for
color highligting, as specified in the environment.
.Sh ENVIRONMENT
The following environment variables affect the execution of
.Nm :
.Bl -tag -width "TOPCOLORS"
.It Ev TOP
The environment variable
.Ev TOP
is examined for options before the command line is scanned.
This enables a user to set his or her own defaults.
The number of processes to display
can also be specified in the environment variable
.Ev TOP .
The options
.Dq Fl C ,
.Dq Fl I ,
.Dq Fl S ,
and
.Dq Fl u
are actually toggles.
A second specification of any of these options will negate the first.
Thus a user who has the environment variable
.Ev TOP
set to
.Dq Fl I
may use the command
.Dq Nm Fl I
to see idle processes.
.It Ev TOPCOLORS
The environment variable is a sequence of color specifications, separated
by colons.
Each specification takes the form tag=min,max#code where
.Li tag
is the name of the value to check,
.Li min
and
.Li max
specify a range for the value, and
.Li code
is an ANSI color code.
Multiple color codes can be listed and separated with semi-colons.
A missing
.Li min
implies the lowest possible value (usually 0)
and a missing
.Li max
implies infinity.
The comma must always be present.
When specifying numbers for load averages, they should be multiplied by 100.
For example, the specification
.Li 1min=500,1000#31
indicates that a 1 minute load average between
5 and 10 should be displayed in red.
Color attributes can be combined.
For example, the specification
.Li 5min=1000,#37;41
indicates that a 5 minute load average higher than 10 should be displayed
with white characters on a red background.
A special tag named
.Li header
is used to control the color of the header for process display.
It should be specified with no lower and upper limits, specifically
.Li header=,#
followed by the ANSI color code.
.El
.Sh SEE ALSO
.Xr kill 1 ,
.Xr ps 1 ,
.Xr stty 1 ,
.Xr mem 4 ,
.Xr renice 8
.Sh AUTHORS
.An William LeFebvre
.Sh BUGS
As with
.Xr ps 1 ,
things can change while
.Nm
is collecting information for an update.
The picture it gives is only a close approximation to reality.
.\" .Sh COPYRIGHT
.\" Copyright (C) 1984-2007 William LeFebvre.
.\" For additional licensing information, see
.\" http://www.unixtop.org/license/