The top program provides a dynamic real-time view of a running system. It can display system summary information as
well as a list of tasks currently being managed by the Linux kernel. The types of system summary information shown and
the types, order and size of information displayed for tasks are all user configurable and that configuration can be
made persistent across restarts.
The program provides a limited interactive interface for process manipulation as well as a much more extensive inter-
face for personal configuration – encompassing every aspect of its operation. And while top is referred to through-
out this document, you are free to name the program anything you wish. That new name, possibly an alias, will then be
reflected on topâs display and used when reading and writing a configuration file.
The program atop is an interactive monitor to view the load on a Linux system. It shows the occupation of the most
critical hardware resources (from a performance point of view) on system level, i.e. cpu, memory, disk and network.
It also shows which processes are responsible for the indicated load with respect to cpu- and memory load on process
level. Disk load is shown if per process “storage accounting” is active in the kernel or if the kernel patch âcntâ has
been installed. Network load is only shown per process if the kernel patch has been installed.
iftop listens to network traffic on a named interface, or on the first interface it can find which looks like an exter-
nal interface if none is specified, and displays a table of current bandwidth usage by pairs of hosts. iftop must be
run with sufficient permissions to monitor all network traffic on the interface, on most systems this means that it must be run as root.
By default, iftop will look up the hostnames associated with addresses it finds in packets. This can cause substantial
traffic of itself, and may result in a confusing display. You may wish to suppress display of DNS traffic by using fil-
ter code such as not port domain, or switch it off entirely, by using the -n option or by pressing n when the program
By default, iftop counts all IP packets that pass through the filter, and the direction of the packet is determined
according to the direction the packet is moving across the interface. Using the -F option it is possible to get iftop
to show packets entering and leaving a given network. For example, iftop -F 10.0.0.0/255.0.0.0 will analyse packets
flowing in and out of the 10.* network
mytop – display MySQL server performance info like `top’
In order for mytop to function properly, you must have the following:
* Perl 5.005 or newer
* DBI and DBD::mysql
* Term::ReadKey from CPAN
Most systems are likely to have all of those installed–except for Term::ReadKey. You will need to pick that up from
Enter into cpan shell and install the module
[root@dev-01 ~]# cpan
cpan> install Term::ReadKey
Install the packages using cpan shell interface
This program is a free (GPL) ncurses-based process viewer.
It is similar to top, but allows to scroll the list vertically and horizontally to see all processes and their full
Tasks related to processes (killing, renicing) can be done without entering their PIDs