BugGyaan#12: Getting Started with Linux
Knowing the filesystem and understanding the structure of the folders is an essential part of understanding how to interact with it.
The specialty of LINUX is that we cannot access the subdirectory without seeking permission from the root and directory. Thus, LINUX has a strict hierarchical file management system defined by FHS or the filesystem Hierarchy Standard maintained by LINUX.
After installing your Linux (If you haven’t yet, follow our tutorial here ),The basic commands comprise the only way to actually explore the filesystem. Here is an overview of the basic commands:
cd :- change the directory
ls :- list the contents of a directory
mv :- rename or move files
whoami :- This command will remind you of your username
pwd :- to know the path of a directory
mkdir :- This is a LINUX command to create a new directory
rmdir :- removes a directory
rm :- removes files and the directory
touch :- used to create new and empty files
cp :- used to copy files
cat :- To display and concatenate files
chmod :- This is the command used to change the access privileges
echo :- It helps to move data into a file
sudo : — this command is used execute a command with admin level or root privileges
hostname I :- this command is used to find the IP address of the system
ping :- this command is used to find whether the destination system is reachable or not
man :- It is used to get the manual pages of the respective commands
vi :- It’s a text editor used to add text to the file
Shortcuts in LINUX:
1. Ctrl+L — Clears the screen
2. Ctrl+S — pause all the command output to the screen
3. Ctrl+Q — Resume output to the screen after pausing
4. Ctrl+C — Break out of aprocess or terminal
5. Ctrl+Z — Run a program in the background
6. Ctrl+A — Cursor moves to the beginning of the line
7. Ctrl+Alt+T — Open command line
When it comes to the filesystem itself,
Here are a few of the directories and what exactly they deal with.(There may be a few in this list that aren’t in the flowchart. This is because they may be sub-folders of a larger folder that over-arches multiple functionalities
/bin
/bin is the directory that contains binaries, that is, some of the applications and programs you can run. You will find the ls program mentioned above in this directory, as well as other basic tools for making and removing files and directories, moving them around, and so on. There are more bin directories in other parts of the file system tree, but we’ll be talking about those in a minute.
/boot
The /boot directory contains files required for starting your system. Do I have to say this? Okay, I’ll say it: DO NOT TOUCH!. If you mess up one of the files in here, you may not be able to run your Linux and it is a pain to repair. On the other hand, don’t worry too much about destroying your system by accident: you have to have superuser privileges to do that.
/dev
/dev contains device files. Many of these are generated at boot time or even on the fly. For example, if you plug in a new webcam or a USB pendrive into your machine, a new device entry will automagically pop up here.
/etc
/etc is the directory where names start to get confusing. /etc gets its name from the earliest Unixes and it was literally “et cetera” because it was the dumping ground for system files administrators were not sure where else to put.
Nowadays, it would be more appropriate to say that etc stands for “Everything to configure,” as it contains most, if not all system-wide configuration files. For example, the files that contain the name of your system, the users and their passwords, the names of machines on your network and when and where the partitions on your hard disks should be mounted are all in here. Again, if you are new to Linux, it may be best if you don’t touch too much in here until you have a better understanding of how things work.
/home
/home is where you will find your users’ personal directories. In my case, under /home there are two directories: /home/paul, which contains all my stuff; and /home/guest, in case anybody needs to borrow my computer.
/lib
/lib is where libraries live. Libraries are files containing code that your applications can use. They contain snippets of code that applications use to draw windows on your desktop, control peripherals, or send files to your hard disk.
There are more lib directories scattered around the file system, but this one, the one hanging directly off of / is special in that, among other things, it contains the all-important kernel modules. The kernel modules are drivers that make things like your video card, sound card, WiFi, printer, and so on, work.
/media
The /media directory is where external storage will be automatically mounted when you plug it in and try to access it. As opposed to most of the other items on this list, /media does not hail back to 1970s, mainly because inserting and detecting storage (pendrives, USB hard disks, SD cards, external SSDs, etc) on the fly, while a computer is running, is a relatively new thing.
/mnt
The /mnt directory, however, is a bit of remnant from days gone by. This is where you would manually mount storage devices or partitions. It is not used very often nowadays.
/opt
The /opt directory is often where software you compile (that is, you build yourself from source code and do not install from your distribution repositories) sometimes lands. Applications will end up in the /opt/bin directory and libraries in the /opt/lib directory.
A slight digression: another place where applications and libraries end up in is /usr/local, When software gets installed here, there will also be /usr/local/bin and /usr/local/lib directories. What determines which software goes where is how the developers have configured the files that control the compilation and installation process.
/proc
/proc, like /dev is a virtual directory. It contains information about your computer, such as information about your CPU and the kernel your Linux system is running. As with /dev, the files and directories are generated when your computer starts, or on the fly, as your system is running and things change.
/root
/root is the home directory of the superuser (also known as the “Administrator”) of the system. It is separate from the rest of the users’ home directories BECAUSE YOU ARE NOT MEANT TO TOUCH IT. Keep your own stuff in you own directories, people.
/run
/run is another new directory. System processes use it to store temporary data for their own nefarious reasons. This is another one of those DO NOT TOUCH folders.
/sbin
/sbin is similar to /bin, but it contains applications that only the superuser (hence the initial s) will need. You can use these applications with the sudo command that temporarily concedes you superuser powers on many distributions. /sbin typically contains tools that can install stuff, delete stuff and format stuff. As you can imagine, some of these instructions are lethal if you use them improperly, so handle with care.
/usr
The /usr directory was where users’ home directories were originally kept back in the early days of UNIX. However, now /home is where users kept their stuff as we saw above. These days, /usr contains a mish-mash of directories which in turn contain applications, libraries, documentation, wallpapers, icons and a long list of other stuff that need to be shared by applications and services.
But many modern Linux distributions just put everything into /usr/bin and have /bin point to /usr/bin just in case erasing it completely would break something. So, while Debian, Ubuntu and Mint still keep /bin and /usr/bin (and /sbin and /usr/sbin) separate; others, like Arch and its derivatives just have one “real” directory for binaries, /usr/bin, and the rest or *bins are “fake” directories that point to /usr/bin.
/srv
The /srv directory contains data for servers. If you are running a web server from your Linux box, your HTML files for your sites would go into /srv/http (or /srv/www). If you were running an FTP server, your files would go into /srv/ftp.
/sys
/sys is another virtual directory like /proc and /dev and also contains information from devices connected to your computer. In some cases you can also manipulate those devices.
/tmp
/tmp contains temporary files, usually placed there by applications that you are running. The files and directories often (not always) contain data that an application doesn’t need right now, but may need later on.
You can also use /tmp to store your own temporary files — /tmp is one of the few directories hanging off / that you can actually interact with without becoming superuser.
/var
/var was originally given its name because its contents was deemed variable, in that it changed frequently. Today it is a bit of a misnomer because there are many other directories that also contain data that changes frequently, especially the virtual directories we saw above.
Conclusion :
Although there are minor differences between Linux distributions, the layout for their filesystems are mercifully similar. So much so that you could say: once you know one, you know them all. And the best way to know the filesystem is to explore it.
You cannot damage your filesystem just by looking at it, so move from one directory to another and take a look around. Soon you’ll discover that the Linux filesystem and how it is laid out really makes a lot of sense, and you will intuitively know where to find apps, documentation, and other resources