Wednesday 28 December 2011

Adding Regular User To Sudoers File In Linux

Hi everybody, this time I am writing about the different command line methods of adding regular user to the sudoers file in linux or in more obvious way, giving access to root privilege to certain regular users. The sudoers file(located at /etc/sudoers by default[in my distro i.e. ubuntu]) contains the information of groups and users who can execute commands with root privilege. I'll list 3 ways of adding users to the sudoers list so continue reading the post.

Method 1
The first way is to use the usermod command to append the user to the admin group. Since the admin group has the privilege of executing commands with sudo privilege, adding the user to the admin group is one easy way to add regular user to the sudoers file. The example command is as below(Replace user with the proper username which you want to add to sudoers list):

sudo usermod -a -G admin user

Method 2
This method is similar as above however the command is adduser this time and the command is even more simpler to remember. Just specify the respective user to be added to the admin group as below:

sudo adduser user admin

Method 3
The last method I'm writing about is the safe way of editing sudoers files. Linux advises to use visudo command to edit /etc/sudoers so that possible errors while writing in sudoers file can be avoided. Typing just visudo would open the /etc/sudoers file for editing, and in case, if you want to edit sudoer file in alternate location, type visudo -f sudoer_with_path. Anyway, to add new user to the default sudoers file, type sudo visudo and add the line as below(Replace user with the proper username to whom you want to give sudo privilege) at the end of file:

user ALL = (ALL) ALL

I hope these methods come useful for you.


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Saturday 24 December 2011

Hiding Information In Text Files Using Notepad [Windows]

Hi everybody, I had long ago read about hiding information inside text files using notepad and today I suddenly remembered while doing some other task. So I am sharing this little trick of hiding information inside the text file using notepad.

Open command prompt (Run-> Cmd) and then navigate to the directory (using cd command) where you want to save your text file. Now, type the following command:

notepad file.txt:mypassword


Replace filename part and password with yours as shown in the screenshot above and then you will be asked if you wish to create a new file or not(See the screenshot below) and then click on Yes to create the file.



Now enter your secret information in the file and save the file. Close the file and if you need to access the contents later, you will have to use the exact command you used while creating the file. If you or someone else edits your file without giving the password, your original hidden content will not be erased and you can still access the content with your original command.

I hope this trick is new for you. :)


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Thursday 22 December 2011

First Thing To Try When Encountered An Odd Error In Eclipse

Hi everybody, this is always worth trying when you encounter some unknown and odd error while developing applications with Eclipse IDE. You may encounter errors even though every line of your code is syntactically correct and still you can't find what exactly is the error. Sometimes you might spend hours trying to find error but actually there might be no error in your application.

To clean the current project in Eclipse, go to Project -> Clean and it will clean all the compiled stuffs and will give you a fresh start for the compilation. Keep in mind this little trick and you might find useful several times while you are working on Eclipse.


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Very Simple PHP Obfuscator Tool From Techgaun

Hi everybody, I've coded a very small snippet of code that will perform very basic PHP obfuscation so that programmers can protect their code from non-programmers. The obfuscation is by no means the advanced one and easily reversible. Only purpose is to prevent script kiddies and leechers from taking away your source code and distributing those as theirs.

Click here to access the PHP Obfuscator.

I hope it becomes useful sometimes. :)


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Sunday 18 December 2011

Copying Files From Remote Server Using SCP In Linux

Hi everybody, sometimes you need to copy files from remote server and only thing you have access to might be SSh. If you can access remote server via SSh, then you can copy files from the remote server using scp(secure file copy). This short tip will help you copy files from remote server using scp.

Scp is remote secure file copy program that makes use of SSh for the data transfer and uses the SSh authentication. The general syntax is as below:

scp -P ssh_port user@server:remote_file_path local_file_path

Following was the command I used to copy a file from remote server to my computer. It will then ask for the password for the corresponding user before you can copy the file.

scp -P 222 netadmin@192.168.0.1:/home/kubh/Desktop/torrent_trackers_list.txt /samar/torrent_trackers.txt

Also, there are GUIs for this purpose as well such as WinSCP for windows and Krusader file manager and gftp for linux distros. GUI would make things easier but still I am used to with command lines and I hope you are as well.

I hope this helps. :)

Edit(Dec 19): Paths with whitespaces must be escaped with \ character. An example of this is as below:

samar@Techgaun:~$ scp -P 222 "netadmin@192.168.0.1:/home/netadmin/Downloads/Hostel\ Part\ III\ \(2011\)\ DVDRip\ 400MB/HOST.DVD_urgrove.com.mkv.002" /samar/Moviez/Hostel1.mkv.002

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Saturday 17 December 2011

Download Good List of Torrent Trackers

I have uploaded a text file containing many torrent tracker URLs. Number of seeders might increase if we have more torrent trackers for the torrent file we are downloading. This post will help you how to add those trackers; I had written that post specifically for utorrent however the process will be similar for other torrent clients.

Download Torrent Tracker List


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Friday 16 December 2011

Useful Aliases To Make Things Easier In Linux

In this post we will see some of the useful aliases that I have made to work faster while I'm working in my system. From that, you can figure out such useful aliases for yourself. With this little customization, you will find so much ease and speed in doing different tasks you need to perform repeatedly.


Either you are a regular linux user or system administrator or tech-geek, you will want to make use of alias to makes several things shorter and easier.

Temporary aliases can be created using the alias command in the terminal. So to test the aliases I've posted below, you can type them in the terminal to see the effect temporarily. If you want to make aliases permanent, you can edit ~/.bashrc file and add those aliases inside this file. Even better, to separate aliases from the .bashrc file, you can put all your aliases by creating a new file ~/.bash_aliases and paste all your aliases in this file. Either way, you'll achieve the permanent aliases for yourself and you'll be finding things going easy and fast for you.

Quick Directory Jumps

alias www='cd /opt/lampp/htdocs/' #Navigating to my web root using www command(actually alias)
alias moviez='cd /samar/data/gallery/movies/' #Navigating to my movies folder by typing moviez

Getting out from deep directory structure

alias cd1='cd ..'
alias cd2='cd ../..'
alias cd3='cd ../../..'
alias cd4='cd ../../../..'
alias cd5='cd ../../../../..'
alias cd6='cd ../../../../../..'


The above aliases can help you while you are inside deep directory structure and want to get out to certain outer level in the same structure.

Shortcuts To Frequently Used Commands

alias runlampp='sudo /opt/lampp/lampp start' #run lampp server bundle
alias stoplampp='sudo /opt/lampp/lampp start' #stop lampp server bundle
alias checkmail='grep -in "Subject:" /var/mail/$USER' #overview of mail
alias myserverlogin='ssh netadmin@192.168.0.1 -p 222 -X' #ssh login to server
alias rootnaut='sudo nautilus /' #open root nautilus file explorer

With this post, what I would like to say is that there is no limit in making these aliases, eventually you will find the necessary aliases for yourself. If you have any other useful general purpose aliases, please feel free to share as the comment.

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Fast Switching To Previous Directory In Linux Terminal

I had a scenario in which I had to switch between two directories frequently while I was working on the remote server over SSh. Typing the directory paths frequently was getting so tedious that I had to know some way to switch between two directories with a single short command. Here is a small tip that will be useful in such cases.

I am presenting my scenario and you'll be able to adapt with your own scenario. So following are two directories I keep on working always.

/opt/lampp/htdocs/
and
~/gateway/bandMan/

So I have the scenario something like below.

cd /opt/lampp/htdocs/

I cd to the first directory with the command above and then perform series of numerous commands and then suddenly I've to go back to the second directory. And I do so by following command:

cd ~/gateway/bandMan/

Again, after changing the directory, I perform several commands and after finishing my tasks on this folder, I need to switch back to previous directory. And I type the following command:

cd -

How it works
This information is for the tech enthusiasts who like to know how it works. When I navigate to another directory from the shell for the first time, a new environment variable OLDPWD is set which stores the path for previous directory before the last cd command was executed. Now what cd - does is switch to the path that OLDPWD variable is storing. If OLDPWD is empty, you will see the "bash: cd: OLDPWD not set" error.

Isn't it so simple? I hope you like this small tip. :)


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