#3 Creating and reading files

Creating files with touch

The touch command creates an empty file. If the file already exists, it simply updates its modification date without changing its content.

$ touch file.txt
$ ls
file.txt  notes.txt

Like mkdir, the touch command produces no output when it succeeds. Silence is a good sign in bash!

cat — Display contents

cat (short for concatenate) displays the entire contents of a file in the terminal. It's the simplest way to read a file.

$ cat notes.txt
This is a notes file.
Line 2
Line 3

On an empty file, cat displays nothing:

$ cat file.txt
$

head — View the beginning

head displays the first lines of a file. By default, it shows the first 10 lines. Very useful for taking a quick look at a large file.

$ head notes.txt
This is a notes file.
Line 2
Line 3

The -n option lets you choose how many lines to display:

$ head -n 2 notes.txt
This is a notes file.
Line 2

tail — View the end

tail is the counterpart of head: it displays the last lines of a file. Very handy for checking log files, for example.

$ tail notes.txt
This is a notes file.
Line 2
Line 3

With -n 1, you get only the very last line:

$ tail -n 1 notes.txt
Line 3

Summary

Here is a recap of the four commands from this lesson:

touch file.txt   # Create an empty file
cat file.txt     # Display all contents
head file.txt    # Display the beginning
tail file.txt    # Display the end

Your turn

Try the commands touch, cat, head and tail in the terminal below. The file notes.txt contains 3 lines of text for your tests.