Linux Command Line Interface
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Linux Command Line Interface, (CLI from now on) could be at first glance discouraging for the average Joe, since nowadays we are only used to Graphic Interfaces. But don’t let you down, using a command line shell could be, not only very useful, but also kind of funny. This Tutorial will help you move your first steps in the command shell environment.
First, when a Command Line Interface could be useful for you?
- Remote Connection via SSH: SSH remote connection allows to interact with UDOO X86 without physical access to it. SSH is available only with command line interface.
- Using a minimal Linux Distribution without a graphical interface. Some Linux Distribution come without a Graphical User Interface, in order to maximize available resources. Command line interface is your only bet in this scenario
- Some power-users consider CLI the most convenient way to perform code execution and file-system operations. Even if you are not in this category, you may found out that CLI can be very fast when you get used to it.
- Showing up with your mates, the longest your CLI strings, the more rep you’ll get.
So, let’s start this adventure with the very basic Linux commands:
Your first ally, allows users to run programs with the security privileges of root, or superuser.Its name is a concatenation of "su" (substitute user) and "do", or take action . So, if you get an error message saying that “only root can do that”, just use the same command with preceeded by sudo.
In fewer words:
This just enables root privileges once for all, without forcing you to type sudo everytime. It works until you close the shell you are working into.
create an empty file
open an handy text editor, to save and exit, press "ctrl" and "x", and tell yes or no by pressing "y" or "n"
cat shows the content of a file, it speeds up file inspection for smaller files.
Shows you the content of a folder
opens a specific folder
cd /home cd ubuntu
Brings you to a higher folder level
cd /home/ubuntu cd .. # this goes to the /home/<user> folder
brings you to root (top filesystem level)
deletes a file
deletes a folder
rm -rf /home/ubuntu/myfolder rm -rf myfolder
moves a file or a folder. Useful for renaming also
mv myfile /myfolder/myfile mv myfile mysecondfile
copies a file
cp myfile /home/ubuntu/
copies a folder
cp -R myfolder /home/ubuntu/myfolder
creates a folder
Top is a very useful utility, it basically gives you a complete overview of the system’s status. It produces an ordered list of running processes selected by user-specified criteria. Top shows how much processing power and memory are being used, as well as other information about the running processes.
Shows used and available disk space, in megabytes.
Shows networking useful data, like current ip, netmasks and other statistics.
chmod let you set files permissions. This utility is very important for people concerned about security, but it is useful also for coders, since you can set a script as executable with it . For a more comprehensive guide on how to use chmod see here
Shows the messages resulting from the most recent system boot. It is useful for troubleshooting, since you can see which modules are loaded, which binaries are started and so on.
Thanks to this command your SD card lifespan will drastically improve, remember to launch it every time you turn UDOO DUAL/QUAD off, or remove the power. Completes all pending input/output operations. It must be launched as root, or with sudo.
reboots the system
shuts it down