Linux files: touch, cat, nano, vi, brace shortcuts, ls -R and tree

By Ravindra Bagale, trainer · LinkedIn · Last updated: 8 October 2026

1. One-minute recap: directories and paths

Why. Everything today builds on last class. If any line below feels new, read Linux directories and paths: pwd, ls, mkdir, cd, absolute vs relative paths and ~ first.

What you should already know:

Keep ls -r (small r, reverse) apart from ls -R (capital R, recursive). We meet ls -R in section 14.

2. Assignment: build the Ramayan tree

Why. Real projects are trees: a website folder with css, images and js inside; an app with logs and config. You must be able to turn a drawing into folders.

The task. In your home folder, make this tree: Ramayan, inside it Dasarath, and inside Dasarath four folders: Ram, Laxman, Bharat, Shatrughna.

How, step by step (from ~):

1. cd (make sure you are home).
2. mkdir Ramayan
3. mkdir Ramayan/Dasarath
4. mkdir Ramayan/Dasarath/Ram
5. mkdir Ramayan/Dasarath/Laxman
6. mkdir Ramayan/Dasarath/Bharat
7. mkdir Ramayan/Dasarath/Shatrughna
8. Check: ls Ramayan/Dasarath → Bharat Laxman Ram Shatrughna

Each step only works because the step before it made the parent. That is the whole idea of a path: you can't put a folder inside a folder that doesn't exist yet.

The same thing in one line (long version):

mkdir -p Ramayan/Dasarath/Ram Ramayan/Dasarath/Laxman Ramayan/Dasarath/Bharat Ramayan/Dasarath/Shatrughna

1. Four paths, separated by spaces, so four folders.
2. -p makes Ramayan and Ramayan/Dasarath on the way, if they are missing.

3. The brace shortcut: {a,b,c}

Why. The long line above repeats Ramayan/Dasarath/ four times. More typing means more typos.

What. Write the common part once, and put the different names in curly braces, separated by commas:

mkdir -p Ramayan/Dasarath/{Ram,Laxman,Bharat,Shatrughna}

1. Ramayan/Dasarath/ is the common path.
2. {Ram,Laxman,Bharat,Shatrughna} is the list of names.
3. Commas between names, and no spaces anywhere inside the braces.
4. Before mkdir even starts, the shell (bash) expands the line into the four full paths. mkdir receives the long version.

See the expansion yourself. echo prints what the shell will hand to the command, without creating anything:

1. echo Ramayan/Dasarath/{Ram,Laxman} → Ramayan/Dasarath/Ram Ramayan/Dasarath/Laxman
2. echo file{1,2,3}.txt → file1.txt file2.txt file3.txt

Worked example: a website skeleton.

1. mkdir -p mysite/{css,images,js}
2. ls mysite → css images js

4. Files: four ways to make one

Why. Up to now we only made folders. A folder is an empty box until you put files in it.

What. There are four common ways to create a file:

1. touch: makes an empty file.
2. cat: makes a file and lets you type lines into it.
3. nano: a simple editor, like Notepad inside the terminal.
4. vi: a powerful editor found on every Linux server.

They differ in what else they can do after creating:

"Modify" means changing something in the middle, for example turning hi on line 2 into bye. Only an editor can do that.

5. touch: empty files

What. touch followed by one or more names makes empty files.

How.

1. cd (go home), then mkdir -p practice and cd practice.
2. touch my.txt
3. touch 1.txt 2.txt 3.txt (three files in one command)
4. ls → 1.txt 2.txt 3.txt my.txt
5. ls -l my.txt → -rw-r--r--. 1 ec2-user ec2-user 0 Jan 5 10:15 my.txt

The 0 before the date is the size in bytes: the file is empty. You can't write in it, read anything from it or edit it with touch. It only creates.

Its real job: the timestamp.

1. Run ls -l my.txt and note the time, for example 10:15.
2. Wait a minute, then touch my.txt again.
3. ls -l my.txt → the time is now the current time, for example 10:20.
4. The content (still empty here) is unchanged.

6. Dots and extensions: just part of the name

Why. On Windows, .jpg means picture and .mp4 means video. In Linux, things work differently, and knowing how prevents confusion later.

What.

1. A dot is just a character in a name. touch report.ppt photo.jpg song.mp4 makes three empty files.
2. None of them is a real presentation, picture or song. They are empty, whatever the name says.
3. Linux doesn't need an extension to know what's inside a file. The file command looks at the content:
   • file photo.jpg → photo.jpg: empty
   • echo hello > notes.jpg, then file notes.jpg → notes.jpg: ASCII text
4. A name without any dot is fine too: touch ravi makes a file named ravi.

So why use extensions at all? They help people and programs:

1. You see backup.sh and know it's a script.
2. Nginx loads the settings files in its conf.d folder only if they end in .conf.
3. A browser treats index.html as a web page.

7. Why would anyone want an empty file?

Why ask. An empty file sounds useless. In real server work, it isn't.

Real uses:

1. A log file a script will fill. You touch backup.log, then a scheduled script writes a line into it every night: "backup done at 12:00".
2. A placeholder. You plan a website: touch index.html about.html contact.html. The structure is ready; you write the content later.
3. A marker (flag) file. A script creates maintenance.on while it works; other scripts check whether that file exists and wait.
4. Quick test files. Before you learn copying and deleting, you need something harmless to practise on: touch file1 file2 file3.

The idea from class still holds: servers are full of automation (start at 9 AM, stop in the evening, back up at noon, upload every 4 hours). Automation needs files to write into, and those often start empty.

8. One name, one item; capital letters count

What.

1. Inside one folder, a name can be used once: by a file or by a folder, not both.
2. Linux names are case-sensitive: ravi, Ravi, rAvi and RAVI are four different names.

How it behaves (try it):

1. mkdir ravi (a folder)
2. touch ravi → no error, and no file appears. touch just updates the folder's time. ravi is still a folder.
3. touch raju (a file), then mkdir raju → mkdir: cannot create directory ‘raju’: File exists
4. touch Ravi RAVI → two new files. ls shows the folder ravi and the files Ravi and RAVI side by side.

9. cat: writing a file with cat >

Why. touch can't put text in a file. cat can, without opening any editor.

What. cat > my.txt means "take what I type and write it into my.txt". The > sends the output into the file instead of the screen.

How.

1. cat > my.txt
2. The cursor waits on an empty line. There is no prompt: cat is listening.
3. Type first line and press Enter.
4. Type second line and press Enter.
5. On the new empty line, press Ctrl+D. You are back at the prompt.
6. Check: cat my.txt.

Ctrl+D means "end of input". Press it at the start of an empty line. In the middle of a line it only sends that line, so you would have to press Ctrl+D a second time.

10. cat: reading, appending, and the > trap

Read. cat my.txt prints the whole file:

first line
second line

Append (add at the end).

1. cat >> my.txt (two >)
2. Type third line, press Enter, then Ctrl+D.
3. cat my.txt → three lines. The old text stayed; the new line went below it.

The trap: a single > replaces everything.

1. cat > my.txt
2. Type new, Enter, Ctrl+D.
3. cat my.txt → only new. The three old lines are gone.

What cat can't do. In a five-line file, cat can't change line 2 from hi to bye. It can only replace the whole file (>) or add lines at the bottom (>>). To change a line in the middle, use an editor (sections 11 and 16).

11. nano: the easiest editor

Why. cat can't edit a line in the middle. You need an editor, and nano is the friendliest one: it feels like Notepad.

What. nano my.txt opens the file in the editor. If it doesn't exist, nano starts a new, empty file and shows [ New File ] at the bottom.

How to edit.

1. nano my.txt
2. Move with the arrow keys. The mouse doesn't move the cursor by default.
3. Type, delete with Backspace, change anything, anywhere.
4. The bottom two lines list the shortcuts. ^ means Ctrl, so ^X is Ctrl+X.

How to save and exit.

1. Press Ctrl+X.
2. nano asks Save modified buffer?
3. Press Y to save (N discards your changes, Ctrl+C cancels and takes you back to editing).
4. nano shows File Name to Write: my.txt. Press Enter to keep the name.
5. You are back at the prompt. Check with cat my.txt.

If you changed nothing, Ctrl+X exits straight away and asks nothing.

12. File names with spaces, and several files at once

What. A space separates arguments, for files exactly as for folders.

1. nano my file opens two files, my and file, one after the other.
2. nano 'my file' opens one file named my file. "my file" and my\ file work too.
3. Turned into a feature: nano file1 file2 file3 opens three files. Ctrl+X closes the current one and moves to the next. Newer nano versions show which one you are on, for example [1/3].

13. Practice task: the calendar, in the fewest commands

The task.

1. In ~, create a folder calendar.
2. Inside it, three folders: months, weeks, days.
3. In months: files jan, feb, mar.
4. Write January inside jan.
5. In weeks: files week1, week2, week3.
6. In days: files 1, 2, 3.

Try it yourself before reading on.

Solution (five commands):

1. mkdir -p calendar/{months,weeks,days}
2. touch calendar/months/{jan,feb,mar}
3. touch calendar/weeks/{week1,week2,week3}
4. touch calendar/days/{1,2,3}
5. nano calendar/months/jan → type January → Ctrl+X, Y, Enter.

Check:

1. cat calendar/months/jan → January
2. ls calendar/weeks → week1 week2 week3

Common mistakes:

1. Slashes inside the braces: {months/weeks/days} is one name with slashes, not three folders. Use commas.
2. Spaces after the commas: {jan, feb, mar} isn't expanded (see section 3).
3. Mixed case: the folder Days and a command with days are two different names.

14. ls -R: list everything inside

What. ls -R (capital R, recursive) lists a folder, then every folder inside it, then every folder inside those, and so on.

How.

1. cd (home)
2. ls -R calendar

Output:

calendar:
days  months  weeks

calendar/days:
1  2  3

calendar/months:
feb  jan  mar

calendar/weeks:
week1  week2  week3

Each block starts with a folder's path and a colon, followed by what's inside. It works for small trees; for big ones the output scrolls off the screen.

Don't confuse it with ls -r (small r), which only reverses the order of one listing.

15. tree: the picture view, and installing software

What. tree draws the same information as a picture. It isn't installed on Amazon Linux by default.

How to install it:

sudo yum install tree -y

1. sudo: run this one command as the administrator (root). Installing software changes the system, so it needs admin rights.
2. yum: the package manager. It downloads software from Amazon's repositories and installs it.
3. install: the action.
4. tree: the package name.
5. -y: answer "yes" automatically to the "Is this ok?" question.

Then:

1. tree calendar
2. The output ends with 4 directories, 9 files.

Every command is a small program.

1. ls, mkdir, touch and cat are programs stored in /usr/bin. They come with Linux.
2. tree is one more program; we installed it ourselves.
3. Before installing, command -v tree prints nothing. After installing, it prints /usr/bin/tree.

16. vi: the editor on every server

Why. nano is friendly, but it isn't always installed. vi is on practically every Linux server, so you must at least know how to type, save and get out.

What. vi has modes:

1. Command mode. vi opens here. Keys are commands, so stray key presses don't type into your file.
2. Insert mode. Now keys type text. The bottom line shows -- INSERT --.

How.

1. vi notes.txt
2. Press i. The bottom shows -- INSERT --.
3. Type your text. Use the arrow keys to move.
4. Press Esc. You are back in command mode.
5. Type :wq and press Enter: write (save) and quit.
6. Check: cat notes.txt.

Three ways into insert mode:

To leave without saving: Esc, then :q! and Enter.

17. Try at home

Recap

Samjla ka? Ghari tree install kara, vi madhe ek file lihun bagha. Pudhchya class madhe copy karayla shikuya.

Ravindra Bagale, trainer: linkedin.com/in/ravindra-bagale. The folder and file names (Ramayan, calendar, ravi, my.txt, photo.jpg, fruits.txt and the rest) are examples for learning. Command outputs were checked with GNU bash, coreutils, nano and tree, the same tools Amazon Linux 2023 uses; the time in ls -l examples is illustrative.