Usefull Linux commands

1.copy a file from source location to destination:

cp source destination:

Ex: cp /root/qwertyt/doc.ppt  /root/qwertyt/test2

2.Lists the files in the present directory

ls

3.Lists the last few files created
ll -lrt 

4.Change Directory

cd

Ex: cd test2

5.Make Directory:

 mkdir

6.Remove file :

rm -rf filename

7.Change access permissions 

chmod -Rf 755 directory

8.Displays first n lines

head -n

Ex: head -5 test5 9.Displays last n linestail -n

Ex: tail -5 test5 

10.Print Working Directory:

pwd 

11.cat:

Display the contents of a file

12.Clear terminal screen:

clear

13.Compare two files: 

cmp 

14.Display or change the date & time:date 

15.Display the differences between two files:

diff

16.Exit the shell:

exit

17.Search file(s) for lines that match a given pattern:

grep

18.Print user and group id's;

id

19.List active jobs:

jobs 

20.Stop a process from running:

kill

21.Help manual:

man

22.Rename files;

rename

23.Reverse lines of a file:

rev

24.create a new file:

touch

PERL: SHORTCTUS

1. <STDIN> Command is used to scan the inputs.

   Ex:

$a=<STDIN>;

You can shorten this command as shown below,

$a=<>;

2. Consider an example,

print “Enter a number \n”;

$a=<STDIN>;

if($a=1)

{

print “..............................\n”;

}

You can shorten the above script as shown below,

print “Enter a number \n”;

if(<>=1)

{

print “..............................\n”;

}

No need to save the scanned inputs in a variable, You can compare the scanned inputs directly.

3.Use EOT command to print multiple lines.

Ex:

print << 'EOT';

ENTER 1 for .....................

ENTER 2 for .....................

ENTER 3 for .....................

ENTER 4 for .....................

EOT

MAGIC : DOWNLOAD & INSTALL

Download VLSI LAYOUT TOOL "MAGIC" FOR UBUNTU:

[DEBIAN FILE]

http://tuxmaniac.com/work/packages/magic/magic_7.5.129-1_i386.deb

After downloading, double click on it to install...

NOTE:You can download ngspice from UBUNTU software centre.

LAPTOP TIPS by Venkatraman

LAPTOP TIPS

• Never keep laptop on softmaterials like bed or on any clothes. The reason is that processor fan will not get ventilation which results in processor failure as well as battery life will be reduced.

All ways keep laptop on hard surface..!

• Never put your laptop into the bags without turn it off completely(standby is also not allowed).
• Do not bend the laptop power cable and also always keep the battery charger in ventilated place whicle charging.

These suggestions may be rediculous but very important for long life of your system.

=====>For circuit enthusiasts only.

Automatic Laptop Power dis-connector.

It is really good practice to disconnect the laptop power cable after the use. However many times we (I) forget to do so. Here is a simple circuit which automatically connect or disconnect the laptop to main AC plug.

The automatic circuit shown in the below image needs hardly few electronic components. Please make sure that proper teminals are connected from USB cable to relay coil. Any wrong connection can destroy the laptop USB PORT.

The details of connection is shown in above image. I am using this circuit from last 6-months. If you are interested do this one and if you need any assistance please contact any time.

Regards,
Venkatraman.

venkatramanhm@gmail.com

Ubuntu...! One of the best OS...!

The Ubuntu is one of the most competitive OS(operating system) for Windows. I love Ubuntu because of its simplicity. It comes with thousands of application and that too absolutely free!!. No virus problems...! No drivers needed..! No payments of any thing.Install in half an hour and enjoy 365+365+...... days...!

For engineers, OS like Ubuntu is really great gift. Any thing can be automated,anything can be added any instant of time. For example the circuit simulator like LTSPICE work nicely under wine. Ngspice and other circuit simulator also available. The scilab and octave are equivalent to matlab. There are many things to explore. There are thousands of application.

If you have interest, please go to application---> Ubuntu software center and search for all kind of application.


I heartily congratulate the ubuntu community for such OS.