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Processes in Linux: Fun with Terminal

March 8th, 2013 No comments

Warning: the content may increase your appetite for interest in Linux.
It’s a myth that “processes” are a complex concept. A process is an executing set of machine level instruction or code.
Whenever you are running an application, a process that belongs to this application is running. There are some processes which runs only in the background. They are called daemons in Linux. The process status, “ps” command shows the currently running processes.
Enough with the theory, now let’s get our hands dirty. Open a terminal session on your favorite Linux distribution.

The “ps” command has mainly two options

  • -e lists all running processes
  • -f shows full process status

At the terminal type “ps -ef

 

full_process_list_linux

  • UID – id of user who invoked terminal
  • PID – ID of that process
  • PPID – parent process ID of the running process
  • C – no. of child processes
  • STIME – start time
  • TTY – terminal executing the process, shows “?” when it is a daemon
  • CMD – name of the process

When the system boots only one process exists – the init process, which is invoked by kernel. Kernel is the core of an operating system on which all other drivers and applications exist and run. The first process on the list is thus always be init.

At the terminal type “ps -e

process_list_linux

How to initiate a background process?

Linux is a true multi-user, multitasking OS. You can run more than one process simultaneously. Type the program name followed by an ampersand(&) separated by a space

vlc &

vlc

The “&” allows to run vlc media player in the background of our parent shell.

  • [1] shows number of child process.
  • 3120 is the process ID(PID) of vlc.

 As a side note, try “ps” command on your Android phone or tablet. Fire up a terminal emulator and see what happens

 

 

android_processandroid_process_list

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Hamsphere: Virtual Ham Radio transceiver on your PC

October 6th, 2011 1 comment

Hamsphere simulates a full blown virtual Ham radio transceiver on you system. It can be operated by licensed and unlicensed DX’ers for free. If you are not having Amateur radio license, they will issue you a "call sign" while registering.

What is so great about this Ham Radio Software Transceiver?

No extra hardware needed, just your PC, a microphone, speakers and you are ready to call CQ on the virtual Ham Radio bands.

You can feel audio on Hamsphere with simulations of occasional band noise and fading, as in a real radio transceiver. The user interface looks like a real HF transceiver

hamsphere2

If you are interested in becoming an Amateur radio operator, here is the opportunity to practice it without buying costly amateur radio gear.
Forget about building complex antennas, raising it on high mast, antenna tuners etc. All you need is an Internet connection and Java support.
Voice (SSB) and CW (Morse code) are allowed on most bands. On the lower bands we can turn on/off(noise-free) the simulation.

Digital modes were prohibited on HamSphere earlier, but are now supported on the 30m band. RRTY, PSK31, SSTV etc can be used.

Pre-requisites: Download JAVA

Download Hamsphere (Windows, Mac and Linux )

For more updates @Hampshere

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