Htop is ncurses text-mode application (for console or X terminals) for displaying different information for running processes, memory and CPU usage, load averages… It is based on top process viewer (which is already bundled in Linux distributions), with added functionality, mouse support, improved loading and starting.
Atop – ASCII full-screen performance monitor that is capable of reporting the activity of all processes (even if processes have finished during the interval), daily logging of system and process activity for long-term analysis, highlighting overloaded system resources by using colors, etc. In combination with the optional kernel module Netatop, it even shows network activity per process/thread.
Ntop – a network traffic probe that shows the network usage, similar to what the popular top Unix command does. ntop is based on libpcap and users can use a web browser to navigate through ntop (that acts as a web server) traffic information and get a dump of the network status.
Iotop – Iotop is a Python program with a top like UI used to show of behalf of which process is the I/O going on.
Nload – console application which monitors network traffic and bandwidth usage in real-time. It visualizes the in- and outgoing traffic using two graphs and provides additional info like total amount of transfered data and min/max network usage.
Iftop – does for network usage what top does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts.
Iptstate – a top-like interface to your netfilter connection-tracking table. Using iptstate you interactively watch where traffic crossing your netfilter/iptables firewall is going, sort by various criteria, limit the view by various criteria, as of version 2.2.0 you can even delete states from the table.
Nethogs – small ‘net top’ tool. Instead of breaking the traffic down per protocol or per subnet, like most tools do, it groups bandwidth by process. NetHogs does not rely on a special kernel module to be loaded. If there’s suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this. This makes it easy to identify programs that have gone wild and are suddenly taking up your bandwidth.
“So long and thanks for all that fish.”