ln the Information Technology world is quite common to face Linux systems, either because it’s “cheaper” to keep Linux server with good security tools, or because it provides the user a more complete control of the operating system.
Regardless the motivation behind the choice for using Linux systems, it’s an obligatory requirement to the IT professional know how to use, even a little, the Command Line Interface. I’ll help you with that, giving you a minimal set of “have to know” commands.
LS
It stands for “list”. Yes: it simply lists the content of the current folder, showing you files and folders.
ls -l
It shows everything in a “long format”, providing informations about permissions, ownership, size, etc.
At the image above, “r” stands for “read”, “w” for “write” and “x” for “execute”, permissions. We have three blocks with those permissions, each one containing the sequence “rwx”: the first block corresponds to the permission of the owner; the second, permissions of the owner’s group; finally, the third, other users’ permissions.
ls -lh
Similar to the previous one, but it shows sizes in a “human” readable shape, showing unities like “MB”, “KB”, and so on, instead of “bytes”. Pay attention to this “h” in linux, because almost always it stands for “human readable”.
ls -a
It shows all, including hidden files and folders.
ls ..
It shows the content of the parent directory. Pay attention to the two dots: it will always represent the parent directory.
PWD
It stands for “Print Working Directory” and it’s exactly what this command does.
CD
It allows you to “enter” in the specified directory.
cd ..
It puts you in the parent directory.
cd ~
It puts you in the current user’s home.
cd –
It’s a magical command that takes you to the previous visited directory. Realise the difference between it and “cd ..”. Look the image below:
Did you get it?
MKDIR
It creates a specified directory
CP
It copies a file or directory. In the case of directories, you have to add the parameter “-r” in order to do the copy recursively.
MV
It moves a file or directory to another location. We may use mv command to provide a simple strategy to turn a specified file as a hidden file, like that:
mv file.txt .file.txt
When you have a file name starting with a dot in Linux, it means it’s a hidden file.
Did you get it?
MKDIR
It creates a specified directory
Friends, for now it’s all! I hope you liked! Keep in touch for suggestions!
By Igor Magalhães Oliveira
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