Friday, September 7, 2007

HTOP - interactive process viewer alternative


This is HTOP, an interactive process viewer for Linux. It is a text-mode application (for console or X terminals) and requires ncurses. Tested with Linux 2.4 and 2.6. HTOP process viewer is not designed to replace the current well used linux 'top' command, but htop is an alternative with newly added and enhanced features that might be useful to other users too.

Htop operates interactively, using keyboard keys, arrows, and mouse driven operations. Htop also comes with its own progress meter that moves back and forth based on current values taken from CPU, memory and swap statistics. Htop process viewer views linux process and threads the same way like top command does, however, htop displays them in a faster way and much more interfactively compared to well known top command.

Since HTOP process viewer is text-based user-friendly interface. Tasks related to process killing, renicing can be done directly using keyboard arrow keys and mouse controls, as the PIDs can be selected by mouse or keyboard function keys and arrows without any further need for specifying PID numbers,

Cool HTOP, works nice and alternatively easy.

Comparison between HTOP and TOP:

* In 'htop' you can scroll the list vertically and horizontally to see all processes and complete command lines.
* In 'top' you are subject to a delay for each unassigned key you press (especially annoying when multi-key escape sequences are triggered by accident).
* 'htop' starts faster ('top' seems to collect data for a while before displaying anything).
* In 'htop' you don't need to type the process number to kill a process, in 'top' you do.
* In 'htop' you don't need to type the process number or the priority value to renice a process, in 'top' you do.
* 'htop' supports mouse operation, 'top' doesn't
* 'top' is older, hence, more used and tested.


HTOP process viewer can be installed in a flash, simply by issuing

# yum -y install htop


# htop



Space - Tag": mark a process. Commands that can operate on multiple processes, like "kill", will then apply over the list of tagged processes, instead of the currently highlighted one.

U "Untag" all processes (remove all tags added with the Space key).

s Trace process system calls: if strace(1) is installed, pressing this key will attach it to the currently selected process, presenting a live update of system calls issued by the process.

F1, h Help screen

F2, S Setup screen. There you can configure meters displayed on the top side of the screen, as well as set various display options,choose among color schemes and select the layout of the displayed columns.

F3, / Incremental process search: type in part of a process command line and the selection highlight will be moved to it. While insearch mode, pressing this key will cycle through matching occurrences.

F4, I Invert sort order: if sort order is increasing, switch to decreasing, and vice-versa.

F5, t Tree view: organize processes by parenthood, and layout the relations between them as a tree. Toggling the key will switch between tree and your previously selected sort view. Selecting a sort view will exit tree view.

F6, > Select field for sorting. The sort field is indicated by a highlight in the header.

F7, ], -
F8, [, + Decrease selected process priority (add to ’nice’ value)

F9, k "Kill" process: sends a signal which is selected in a menu, to one or a group of processes. If processes were tagged, sends the signal to all tagged processes. If none is tagged, sends to the currently selected process.

F10, q Quit

u Show only processes owned by a specified user.

M Sort by memory usage (top compatibility key).

P Sort by processor usage (top compatibility key).

T Sort by time (top compatibility key).

F "Follow" process: if the sort order causes the currently selected process to move in the list, make the selection bar follow it.
This is useful for monitoring a process: this way, you can keep a process always visible on screen. When a movement key is used, follow" loses effect.

K Hide kernel threads: prevent the threads belonging the kernel to be displayed in the process list. (This is a toggle key.)

H Hide user threads: on systems that represent them differently than ordinary processes (such as recent NPTL-based systems), this can hide threads from userspace processes in the process list. (This is a toggle key.)

Ctrl-L Refresh: redraw screen and recalculate values.

Numbers PID search: type in process ID and the selection highlight will be moved to it.


HTOP web screenshot:

My HTOP screenshot in action:

HTOP FAQs can be seen here.

For more, man htop



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