File Commands in Linux

cat (Concatenate a file)

cat stands for Concatenate.

It is the command that is used to concatenate (read and adds) and print the contents of a file.

The cat utility reads files sequentially, writing them to the standard output (terminal).

You can also use the cat command to create a file.

To create a file, follow the steps as listed below. We are going to create a file called edu_quote.txt

Type cat > edu_quote.txt and press Enter.
Now type Education is the most powerful weapon you can use to change the world. - Mark Twain
Press Ctrl + Z if you are using a Windows machine or Cmd + Z if you are using a Mac machine

What this cat > edu_quote.txt command does is, it reads (or concatenates) the contents (in this case the quote that you typed in) and writes (>) it into a file called edu_quote.txt

To read the contents of a file and print it to the terminal, you can use the cat command.

Now type cat edu_quotes.txt (this time without the > sign between the word cat and edu_quotes.txt) You should see the quote that you typed in displayed on the screen.

Note: The cat command is used extensively in reading and managing files in Linux.

file (Determine file type)

mv stands for Move.
It can be used to move or rename files.

If there is a file that you need to move into another directory you can use the mv command to do so. Let us organize the famous_scientists.txt into the scientists folder.

Type mv famous_scientists scientists/ and press enter.

Type ls and see if the famous_scientists.txt is there. It has been moved to the scientists folder.

Type in cd scientists/

Now see if the famous_scientists.txt is there. ls

touch (Change file timestamp)

touch creates empty files and changes the timestamp of a file.

First change directory into the cd

mv (Move or Rename a file)

The file command is used to determine the type of file.

The file command can be very useful if you need to find out the file is whether it is a text file a zip file or even a malware file.

Go to the home directory if not already there by typing cd home

Type file edu_quote.txt and press enter.

You should see this output.
edu_quote.txt: UTF-8 Unicode text

This is saying that it is a normal UTF-8 text file.

Let's try and read the famous_scientists.txt.

Type cat famous_scientists.txt

The text seems to look all garbled like, PC??N?1U^ofamous_scientists.txtUT ?=2]?=2]ux %[email protected] ?H??o5?? {??_??P"Q;dE???I?f4?!??z????҈? I?[x? &+?3q??lK???C?T?S?ʮ???Y+7PC??N?1U^o??famous_scientists.txtUT?=2]ux PK[?

Why don't we check what type of file this is.

Type file famous_scientists.txt

We can see,
famous_scientists.txt: Zip archive data, at least v2.0 to extract
This means it is not actually a .txt file it is a .zip.

Remember the file command it can come in handy when trying to see what a file really is.

rm (Remove or delete file(s))

rm stands for Remove

diff (Show the difference between two files)

diff stands for Difference

diff3 (Show the difference between three files)

diff3 stands for Difference (between 3 files)

cd <directory>	Change directory
ls	List directory
echo 'contents' > <file>	Write contents to a file
cat <file>	Output contents of file

i	In Command Mode	Change into Insert Mode, you can now insert and edit text in the file
esc	In Insert Mode	Change into Command Mode, you can now execute commands
:wq	In Command Mode	Save and Exit

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Congratulations!

You've completed the scenario!

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