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Understanding Linux File Permissions and Ownerships

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From one of our previous articles "How to manage Linux Users and Groups" we discussed on how Linux becomes a multi-user OS, what is a user and a group with their configurations. By design, even though Linux allows multiple users can use the same computer in the same time without affecting others, Linux doesn't allow you to access or modify files belonging to other users. If Linux allows you to do it, that would be a security risk. But somehow they have implemented a security measure to mitigate that security risk. With that we can make sure only desired users and groups can access the relevant files and directories.

If we take a small demonstration. Here, we will log in as a normal user and try to access a root directory.


It gave a permission denied error when accessing. Why ? That's because /root directory is owned by user root. Only a privileged user can access or modify that.

So, Linux introduces two kind of factors which tells who can access or modify a file as w…

Absolute Path and Relative Path

What is an Absolute Path ?  An absolute path is a fully qualified path. Simply, the path starting from the root "/" and it specifies each an every sub directory  that goes to the destination directory. 
eg : /var/log/messages, /home/student/Videos, /etc/passwd
Like the above, absolute path starts from the root and displays all the directories along to the destination. 
What is a relative Path ?  Not like absolute Path, relative path shows only the path necessary to reach the file from the present directory (means from the currently working directory). 
eg : Guess the absolute path of a specific file is as below.
Absolute Path : /home/student/Documents/myUrlFiles/linuxschool4you.blogspot.com
And if your present working directory is /home/student/Documents, the relative path for linuxschool4you.blogspot.com is myUrlFiles/linuxschool4you.blogspot.com. 
As a summary, if my present directory is  /home/student/Documents So, absolute path and relative path for file linuxschool4you.…

Linux File System Hierarchy

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In the linux file system hierarchy, all the files are stored in a single inverted tree, Because the root directory is on the top of the hierarchy and directories and sub directories are below the root.

The root directory which is "/" as show in the above image is the starting of the file system. More than that "/" is used to seperate the directories like "/etc/passwd  and /etc/group". Below will describe one by one the directories under root.

/boot : The files which needs to start the boot process
/etc : System configuration files.
/home : All the user's home directories are here. In simple words, users home folder.
/root : Home directory of the root user
/bin : User commands
/sbin : Administrative commands
/var : Files which changes by time. Persistence between boot. Dynamically change by time. eg - log files, databases
/dev : Special files which system needs to access hardware.
/proc : contains files which gives system information like /proc/cpuinf…

Why Linux is so powerful ?

Linux is everywhere. It’s may be in your driving car, watching television, your smartphone or could be even the refrigerator you store your food. Yes it is BIG. A STRANGE.
It powers most of the websites you visit in your day today life, and it’s behind virtually all the special effects you see in summer blockbusters. In short, Linux is ubiquitous. And it’s only becoming more and more common.
What does this mean ? There is a corresponding demand for Linux talent with it's rising up. For example, if you go to www.glassdoor.com (a popular technology job recruiting site) you can find almost more than 50,000 jobs requiring Linux system administration skills. You can see, there are a huge number of jobs available for those with the proper skills and it's a good competition actually.

One more thing. Because of being Linux talent so in-demanded, employers are having a hard time finding and keeping qualified sysadmins. As a result of that, employers are offering all kinds of perks to …