Ubuntu

1. To know about the hardware you are using in your computer. The lshw-gui adds a nice gui to the lshw command.

$sudo lshw.

2. To know about the CPU specifically,
$lscpu

3. To know whether your video card is supported by X11,
$lspci
This utility gives a list of all the devices plugged in to your PCI bus.

4. To see what USB devices are on your system,
$lsusb

5. To know about disk subsystem, use blkid utility
It prints out all the available filesystems. With this utility, you can learn what devices are available and what filesystems are being used on them. The associated UUIDs also are available if you want to use them in the entries in /etc/fstab.

6. To see whether your kernel actually is using the available hardware,
$lsmod

Sysinfo gives a GUI view of system info as well.
Another great utility is dmidecode. This will give you a ton of information about your machine


To know about Cpu and others info and their usage:

To obtain CPU information:
head /proc/cpuinfo

To obtain memory (RAM) information
head /proc/meminfo

To obtain partition of your swap space:
# head /proc/swap

To obtain partition sizes:
# head /proc/partitions

for mem info
free -m

$uptime
Shows the information about the system uptime and load averages in last 1,5 and 15 minutes.
if the load averages were 20.68, 5.01, 1.03, I would conclude that the high load had likely started in the last 5 minutes and was getting worse.

$top and $iostat

$lsof - lists information about files opened by processes.
An open file may be a regular file, a directory, a block special file, a character special file, an executing text reference, a library, a stream or a network file (Internet socket, NFS file or UNIX domain socket.) A specific file or all the files in a file system may be selected by path.

Instead of a formatted display, lsof will produce output that can be parsed by other programs. Use -F option and OUTPUT FOR OTHER PROGRAMS section.
In addition to producing a single output list, lsof will run in repeat mode. In repeat mode it will produce output, delay, then repeat the output operation until stopped with an interrupt or quit signal.

$powertop -p

To know about the list of softwares installed in your computer, use
dpkg -l (OR)
dpkg --get-selections > installed.txt (O/P will be in installed.txt file)

To open word documents in command line use catdoc package like cat for normal text files.



8 Great open source desktop productivity tools:
------------------------------------------------
Abiword 2.8.6 - simple word processing application. Allows you connect to another AbiWord user across a network and work on the same document in real time.

Scribus 1.3.8 - desktop publishing program has a macro language GIMP with a number of prepackaged macros (Eg: a calendar generator), can produce professional-quality CMYK PDFs, and even includes a "preflight check" function.

SeaMonkey 2.0.6 - Mozilla's "suite" product, which bundles Web browsing, email, IRC chat, and an HTML editor in one application, hasn't received nearly as much attention as Firefox or Thunderbird, both of which are now incorporated as part of the SeaMonkey bundle.

GIMP 2.6 - GNU Image Manipulation Program, a staple recommendation as an alternative to Photoshop.

Paint.NET 3.5.5 - spectacular program comes closer than any other to replacing Photoshop for the casual user. support for just about every major image format make this program well worth having.

Inkscape 0.48 - Free software's answer to Adobe Illustrator. Its native file format is conventional XML, and it can import and export from a whole bevy of existing vector and raster formats, as well as PDFs.

Dia 0.97 - A flowchart and diagram drawing tool that is much like an AbiWord for illustration, in that it gives you only what you need to create a certain class of design and doesn't burden you beyond that.

FreeMind - a drawing tool specifically for creating "mind maps," or diagrams that illustrate conceptual frameworks.


Ubuntu Useful softwares:
------------------------

(1)pdfedit, Kword, Scribus, flpsed - for editing the PDF documents

Install:
$ sudo apt-get install pdfedit

To start PDFEdit, type:
$ pdfedit /path/to/pdf.file &
$ pdfedit &


$ sudo apt-get install scribus

To use scribus to edit PDF files:
Start scribus > New File > Insert > Image > Double click > Select PDF file

To edit file, enter:
$ flpsed /path/to/pdf-file.pdf &

PDFEdit is the best free open source software for for Linux / Unix-like operating systems. However, it does not support editing protected or encrypted PDF files.

(2)Xfig - for drawing the images in linux(MS Visio is a great tool in windows for drawing images)

Install:
sudo apt-get install xfig

Use: $ xfig

(3)jing - Video capturing tool in linux

(4)Storybook, Writer's Cafe - Tools for writing stories or novels in a structured manner.
Both are cross platform(Run in both Linux and Windows).