top (software)

top

Stable release	3.2.8
Written in	C
Operating system	Unix-like
Type	Process Viewer / System monitor
License	BSD Licenses#3-clause (Unix version), GNU General Public License (Linux version)
Website	www.unixtop.org gitlab.com/procps-ng/procps

top (table of processes) is a task manager program found in many Unix-like operating systems. It produces an ordered list of running processes selected by user-specified criteria, and updates it periodically. Default ordering is by CPU usage, and only the top CPU consumers are shown. top shows how much processing power and memory are being used, as well as other information about the running processes. Some versions of top allow extensive customization of the display, such as choice of columns or sorting method.

There are several different versions of top. The traditional Unix version was written by William LeFebvre and originally copyrighted in 1984.^[1] It is hosted on sourceforge,^[2] and release 3.7 was announced in 2008.^[3]

The Linux top version is part of the procps-ng group of tools. It was originally written by Roger Binn in 1991^[4] but shortly thereafter it was taken over by others.^[5]

top is useful for system administrators, as it shows which users and processes are consuming the most system resources at any given time.

On Solaris, the roughly equivalent program is prstat. MS-DOS has tasklist and graphical Microsoft operating systems have the Windows Task Manager. IBM AIX has an updating running processes list as part of the topas and topas_nmon commands.

The load average numbers in Linux refers to the sum of the number of processes waiting in the run-queue plus the number currently executing. The number is absolute, not relative. And thus it can be unbounded; unlike utilization. The instant variations of the number of processes are damped with a exponential decay formula which is calculated using fixed point math.^[6]

The ps program is similar to top, but instead produces a snapshot of processes taken at the time of invocation.

External links

Wikimedia Commons has media related to top.

FreeBSD freebsd.org: top(1)
BSD top home page and man page
Linux top home page (procps-ng) and man page
Alternate top programs for Linux include atop (uses process accounting) and Htop

References

↑ Unixtop license.
↑ Unixtop FAQ.
↑ SourceForge Unixtop News.
↑ Linux top man page
↑ Linux Top Origins.
↑ "UNIX Load Average Part 2: Not Your Average Average" (PDF). teamquest.com. 2010. Retrieved 2013-06-10.

Unix command-line interface programs and shell builtins

File system	cat chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls mkdir mount mv pax pwd rm rmdir split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pkill ps pstree time top

User environment	clear env exit finger history logname mesg passwd su sudo uptime talk tput uname w wall who whoami write

Text processing	awk banner basename comm csplit cut diff dirname ed ex fmt fold head iconv join less more nl paste printf sed sort spell strings tail tr uniq vi wc xargs yes

Shell builtins	alias cd echo test unset wait

Networking	dig host ifconfig inetd netcat netstat nslookup ping rdate rlogin route ssh traceroute

Searching	find grep locate whatis whereis

Documentation	apropos help man

Miscellaneous	bc dc cal expr lp od sleep true and false

List of Unix utilities

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top (software)

See also

External links

References