Goals: Introduction to the Linux File System, its structure and how to navigate around it, as well as creating, moving and copying files and folders.

What the file system is, and a typical organization / hierarchy.
Some high-level comparison to that of Windows.
Absolute vs relative paths.
Commands: pwd, cd, ls, mv, cp, mkdir, rmdir, rm
History: history
File Ownership and Permissions.

Table of Contents

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Some high-level comparison to that of Windows

	Windows	Linux
Structure	Uses (data) drives C:, D:, E:…	Uses a tree hierarchy starting at “`/`” Known as the root directory.
	`<drive>\<folder01>\<folder02>`	`/<folder01>/<folder02>`
Syntax	Uses the back slash: “\”	Uses the forward slash: “/”
Home folder	`C:\Users\<username>`	`/home/<username>`
Application Install	`C:\Program Files\`	`/usr/`
Folder and Filenames	Case insensitive: FoLdEr = FOLDER	Case sensitive: FoLdEr ≠ FOLDER
		Wherever you are within the hierarchy is known as your current working directory (cwd)

Linux OS General Structure

Linux Hierarchical Structure: Example

Absolute Path: /home/arcc-t05/

Path starts with a “/”

Absolute Path: /home/arcc-t05/workshop/projects/p01/etc/

Relative Path: workshop/projects/p01/etc/

Path does not start with a “/”

Relative Path: p01/etc/

Ex: Starting at / (root), what is the absolute path to the bits folder?

Answer:

Expand

title	Answer

/usr/include/bits/

Ex: Starting in the home folder what is the relative path to the Jan folder?

Answer:

Expand

title	Answer

arcc-t05/workshop/data/2023/Jan/

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If you are following along as part of a scheduled training or bootcamp, please replace the arccanetrain directory with the project directory you’ve been provided for your specific training/bootcamp. If you are training independently, please use your own project folder, but contact arcc-help@uwyo.edu if you would like a copy of the files and directories used in our examples.

Commands:

Used to perform certain operating system tasks through the Command Line Interface, as directed by the interpreter (as opposed to a Graphical Interface Interpreter we would usually use).

<command --help>

Command

Description

pwd

Code Block
pwd: pwd [-LP] Print the name of the current working directory.

cd

Code Block
cd: cd [-L\|[-P [-e]] [-@]] [dir] Change the shell working directory.

ls

Code Block
Usage: ls [OPTION]... [FILE]... List information about the FILEs (the current directory by default)

mkdir

Code Block
Usage: mkdir [OPTION]... DIRECTORY... Create the DIRECTORY(ies), if they do not already exist.

mv

Code Block
Usage: mv [OPTION]... [-T] SOURCE DEST or: mv [OPTION]... SOURCE... DIRECTORY or: mv [OPTION]... -t DIRECTORY SOURCE... Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

Commands: <command --help>

Command

Description

cp

Code Block
Usage: cp [OPTION]... [-T] SOURCE DEST or: cp [OPTION]... SOURCE... DIRECTORY or: cp [OPTION]... -t DIRECTORY SOURCE... Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY.

rmdir

Code Block
Usage: rmdir [OPTION]... DIRECTORY... Remove the DIRECTORY(ies), if they are empty.

rm

Code Block
Usage: rm [OPTION]... [FILE]... Remove (unlink) the FILE(s).

pwd: Print the name of the current working directory

Info
If you get lost, then you can jump back to the home folder.

Code Block
[arcc-t05@blog1 ???]$ cd [arcc-t05@blog1 ~]$

Info
The `~` “tilda” character represents your home directory.

Info
Use the `pwd` to confirm your current working directory, which after the above command will be home.

Code Block
[arcc-t05@blog1 ~]$ pwd /home/arcc-t05

cd: Change the shell working directory

Info
Start by navigating back to home.

Code Block
[arcc-t05@blog1 ???]$ cd [arcc-t05@blog1 ~]$

Info
Move up one level, into the current folder’s parent.

Code Block
[arcc-t05@blog1 ~]$ cd .. [arcc-t05@blog1 ~]$ pwd /home

Info
Move up another level into the root folder.

Code Block
[arcc-t05@blog1 home]$ cd .. [arcc-t05@blog1 /]$ pwd /

cd: Change working directory (cont)

Info
Navigate into the `opt` folder.

Code Block
[arcc-t05@blog1 /]$ cd opt [arcc-t05@blog1 opt]$ pwd /opt

Info
Question: Did we define an an absolute or relative path?

Answer:

Did we define an an absolute or relative path?

Expand

title	Answer

When we print out the working directory, we are presented with a '/' in front of opt, however when we changed directories to opt, our cd command did not have a '/'. Therefore, we defined the relative path to the opt directory.

cd: Change the shell working directory

Info
First reset back to home.

Code Block
[arcc-t05@blog1 opt]$ cd [arcc-t05@blog1 ~]$

Info
Navigate into the `/usr/include/asm` folder.

Code Block
[arcc-t05@blog1 ~]$ cd /usr/include/asm [arcc-t05@blog1 asm]$ pwd /usr/include/asm

Info
Question: Did we define an absolute or relative path?

Answer:

Expand

title	Answer

Relative path, since we specified the full path, starting with root: /

Info
Navigate up two levels:

Code Block
[arcc-t05@blog1 asm]$ cd ../.. [arcc-t05@blog1 usr]$ pwd /usr

Info
Navigate back home:

Code Block
[arcc-t05@blog1 usr]$ cd [arcc-t05@blog1 ~]

ls: List information about the FILEs (cwd by default)

Info
Take a look at the `ls` command and some of the options it provides.

Info
List files in the user’s home folder.

Code Block
[arcc-t05@blog1 ~]$ ls

Info
List long format that includes ownership and permission details.

Code Block
[arcc-t05@blog1 ~]$ ls -l

Info

List all files, including hidden files and folders start with “.”.

Notice how ‘short-name’ options are grouped.

Code Block
[arcc-t05@blog1 ~]$ ls –a

Info
List all files with long format.

Code Block
[arcc-t05@blog1 ~]$ ls –al

Info
List all files with long format, in reverse order.

Code Block
[arcc-t05@blog1 ~]$ ls –alr

Info
List all files with long format, in reverse order, in human readable form.

Code Block
arcc-t05@blog1 ~]$ ls –alrh

Info
Note how we can use multiple options together.

Info
Demonstrate how to `ls` to a folder outside cwd using an absolute path.

Code Block
# Demonstrate how to ‘ls’ to a folder outside cwd [~]$ ls /project/arccanetrain/arcc-t01 folder01 myfile.txt

mkdir: Create the DIRECTORY(ies), if they do not already exist

Code Block

$ cd
[~]$ ls
Desktop  Documents  Downloads
[~]$ mkdir folder01
[~]$ ls
Desktop  Documents  Downloads  folder01
[~]$ mkdir folder01
mkdir: cannot create directory ‘folder01’: File exists
[~]$ cd folder01/
[folder01]$ pwd
/home/arcc-t05/folder01

Info
If a folder already exists, you can not make it again.

mkdir: Create the DIRECTORY(ies), if they do not already exist

Code Block
[folder01]$ mkdir folder02 folder03 [folder01]$ ls folder02 folder03 [folder01]$ cd folder02/ [folder02]$ pwd /home/arcc-t05/folder01/folder02 [folder02]$ cd ../.. [~]$ pwd /home/arcc-t05

mv: Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

Code Block

$ cd
# Create an empty file.
[~]$ touch myfil.txt
[~]$ ls
Desktop  Documents  Downloads  folder01  myfil.txt
# Rename the file ‘myfil.txt’ to ‘myfile.txt’:
[~]$ mv myfil.txt myfile.txt 
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile.txt

Info
Notice how we have moved the file from one name to a new name - essentially renaming it.

mv: Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

Code Block

# Move the file ‘myfile.txt’ into the directory ‘folder01’
[~]$ mv myfile.txt folder01/
[~]$ ls
Desktop  Documents  Downloads  folder01
# Demonstrate how to ‘ls’ what is in a relative folder.
[~]$ ls folder01/
folder02  myfile.txt

cp: Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY

Code Block

# Navigate back to home:
$ cd

# Use the touch command to create an empty file.
[~]$ touch myfile02.txt
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile02.txt

# Copy (duplicate) a file.
[~]$ cp myfile02.txt myfile02b.txt 
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile02b.txt  myfile02.txt

# Copy a file into an existing folder.
[~]$ cp myfile02b.txt folder01/
[~]$ ls folder01/
folder02  myfile02b.txt  myfile.txt

cp: folders

Code Block

[~]$ cp folder01
cp: missing destination file operand after 'folder01'
Try 'cp --help' for more information.
[~]$ ls folder01
folder02  myfile02b.txt  myfile.txt
[~]$ cp folder01 folder03
cp: -r not specified; omitting directory 'folder01’

Info

You can not use the cp command with no options to copy a folder that has files within it.

Look at the options available. cp -h

In this specifically -r that recursively copy a folder and all its contents.

Code Block
[~]$ cp –r folder01 folder03 [~]$ ls Desktop Documents Downloads folder01 folder03 myfile02b.txt myfile02.txt [~]$ ls folder03 folder02 myfile02b.txt myfile.txt

rmdir: Remove the DIRECTORY(ies), if they are empty

Code Block

[~]$ ls 
Desktop  Documents  Downloads  folder01  folder03  myfile02b.txt  myfile02.txt
[~]$ mkdir folder04
[~]$ ls
Desktop  Documents  Downloads  folder01  folder03  folder04  myfile02b.txt  
myfile02.txt

# Can remove folder04 since it is empty.
[~]$ rmdir folder04
[~]$ ls
Desktop  Documents  Downloads  folder01  folder03  myfile02b.txt  myfile02.txt

[~]$ rmdir folder03/
rmdir: failed to remove 'folder03/': Directory not empty

Info
You can not use `rmdir` to remove a directory that has files still within it. The folder must be empty.

rm: Remove (unlink) the FILE(s)

Code Block

[~]$ cd
[~]$ cd folder03
[folder03]$ ls
folder02  myfile02b.txt  myfile.txt

[folder03]$ ls folder02/
[folder03]$
# ‘folder02’ is empty.
[folder03]$ rmdir folder02/

[folder03]$ ls
myfile02b.txt  myfile.txt
[folder03]$ rm myfile.txt 
[folder03]$ ls
myfile02b.txt
[folder03]$ rm myfile02b.txt

rm: Remove (unlink) the FILE(s)

Code Block

[folder03]$ ls
[folder03]$
# ‘folder03’ is now empty.
[folder03]$ cd ..
[~]$ rmdir folder03/
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile02b.txt  myfile02.txt
# This has taken a lot of individual steps.
# Can we do this quicker?

rm: folders and file(s)

Code Block
[~]$ cd [~]$ rm folder01/ rm: cannot remove 'folder01/': Is a directory

Info
You can not use the `rm` command with no options to remove a folder.

Code Block
[~]$ rm --help Usage: rm [OPTION]... [FILE]... Remove (unlink) the FILE(s). ... -r, -R, --recursive remove directories and their contents recursively ...

Info
Using help we found we can use the `-r` option to remove a folder and all its contents.

Code Block

[~]$ rm -r folder01/
[~]$ ls
Desktop  Documents  Downloads  myfile02b.txt  myfile02.txt
# Can remove multiple files.
[~]$ rm myfile02b.txt myfile02.txt 
[~]$ ls
Desktop  Documents  Downloads
# Alternatively we could have removed above 2 files with: rm myfile* 
# * is a wildcard, so the rm myfile* will remove all starting with the characters "myfile"

rm: WARNING

From the command-line there is NO trash bin.

Using rm/rmdir is FINAL!

history

Code Block

[~]$ history --help
history: history [-c] [-d offset] [n] or history -anrw [filename] or history -ps arg [arg...]
    Display or manipulate the history list.
    ...
[~]$ history 
  ...	
  219  rm -f folder01/
  220  rm -r folder01/
  221  ls
  222  rm myfile02b.txt myfile02.txt 
  223  ls
  224  history
# Repeat command ‘223’
[arcc-t05@blog1 ~]$ !223
ls
Desktop  Documents  Downloads

Exercises

Questions:

How can you return to your home folder?
What command do you use if you’ve forgotten where you are in the folder hierarchy?
How can you list what is in a folder as well as any subfolders?
Go back through the command related slides are try for yourself.

Answers

1: How can you return to your home folder?

Expand

title	Answer

Use: cd or cd ~ as a shortcut to return to your home folder instead of using a cd /home/$USER or cd /home/<insert_your_username>/
cd stands for: change directory

2: What command do you use if you’ve forgotten where you are in the folder hierarchy?

Expand

title	Answer

Use: pwd
This stands for: print working directory.

3: How can you list what is a folder as well as any subfolders?

Expand

title	Answer

ls command lists contents, which flag do we use to get it’s subfolders as well?

Code Block
[]$ man ls -R, --recursive list subdirectories recursively []$ ls -R

-R is for recursive, which relates to repeated application of the rule over successive executions. We continue applying the listings for all subfolders that exist within the top level parent directory.

File Ownership and Permissions

What does the output of ls –l mean?

Code Block

[arcc-t05@blog1 ~]$ cd /project/arccanetrain/intro_to_linux
[arcc-t05@blog1 intro_to_linux]$ ls -al
total 54
drwxrwsr-x  4 salexan5 arccanetrain  4096 Oct  6 08:09 .
drwxrws--- 40 root     arccanetrain  4096 Oct  6 08:09 ..
drwxrwsr-x  2 salexan5 arccanetrain  4096 Oct  5 11:19 clusters
drwxrwsr-x  6 salexan5 arccanetrain  4096 Oct  5 14:56 data
-rw-rw-r--  1 salexan5 arccanetrain   874 Oct  5 15:30 fruits.txt
-rw-rw-r--  1 salexan5 arccanetrain 34472 Oct  5 10:57 software.csv
-rw-rw-r--  1 salexan5 arccanetrain  1603 Oct  6 08:08 vegatables.txt
-rw-rw-r--  1 arcc-t05 arccanetrain    26 Oct  5 07:20 workshop_all.txt
-rw-------  1 arcc-t05 arccanetrain    23 Oct  5 07:20 workshop_me.txt

The first character on the left indicates if it is a directory “d” or a file “-”.

Code Block
drwxrwsr-x clusters # A folder. -rw-rw-r-- workshop_all.txt # A file.

File Ownership and Permissions

Code Block
-rw-rw-r-- 1 arcc-t05 arccanetrain 26 Oct 5 07:20 workshop_all.txt

User: This is the owner of the file/folder. By default, the person who created it becomes its owner.
- arcc-t05 is the owner
Group: A group is a collection of users. The primary purpose of the group is to define a set of privileges for a given resource that can be shared among the users within the group.
- arccanetrain is the group.
- All the arcc-txx users have been setup to be within this group.
Other: This is any other user who has access to the file/folder. This person has neither created the file, nor do they belong to a user group.

Permission Denied

Info
This demonstrates how permissions work. Bare in mind this assumes you’re logged in as user `arcc-t05`.

Code Block
[]$ cd /project/arccanetrain/ []$ ls -al ... # drwxr-sr-x 2 arcc-t01 arccanetrain 4096 May 16 16:26 arcc-t01 ...

Info
The middle set of permissions is “drwxr-sr-x” means no one other than `arcc-t01` has permission to write within this folder.

Code Block
[arccanetrain]$ cd arcc-t01/ # Can arcc-t05 create (write) a file within this folder? [arcc-t01]$ touch text.txt touch: cannot touch 'text.txt': Permission denied

Note
No one, other than `arcc-t01` can create (write) a file within this folder.

If we change directories, and go to /project/arccanetrain/intro_to_linux, what permissions do the contents of this directory have?

Code Block
[arcc-t01]$ cd ../intro_to_linux [arcc-t01]$ ls -al # -rw-rw-r-- 1 arcc-t05 arccanetrain 26 Oct 5 07:20 workshop_all.txt

Info

Any user within the arccanetrain group can read/write the file workshop_all.txt.

Everybody can read it. Do you want anyone outside of this project to be able to read this file?

Code Block
[] ls -al # -rw------- 1 arcc-t05 arccanetrain 23 Oct 5 07:20 workshop_me.txt [intro_to_linux]$ cat workshop_me.txt cat: workshop_me.txt: Permission denied

Note
Only user `arcc-t05` can read/write this file. No one else, not even anyone within the `arccanetrain` group, can view this file.

Exercise: Try it

Code Block

[]$ cd /project/arccanetrain/
[arccanetrain]$ cd arcc-t05
[arcc-t05]$ touch test.txt
# Do you get a “Permission denied”?
# Navigate into the intro_to_linux folder. 
[arcc-t05]$ cd ../intro_to_linux
[intro_to_linux]$ cat workshop_all.txt
Everybody can read this.
[intro_to_linux]$ cat workshop_me.txt
# Do you get a “Permission denied”?
# Can you cd into the /opt folder?
# Justify your answer.
# Can you cd into the /root folder?
# Justify your answer.

Answers

Can you cd into the /opt folder?

Expand

title	Answer

Code Block
[arcc-t05@blog1 ~]$ cd /opt [arcc-t05@blog1 opt]$

Yes

Can you cd into the /root folder?

Expand

title	Answer

Code Block

[arcc-t05@blog1 ~]$ cd /root
-bash: cd: /root: Permission denied
[arcc-t05@blog1 ~]$ ls -l /
...
# “other” has read permissions
drwxr-xr-x.    5 root root    43 Jun 26 11:47 opt
...
# No permission set for other read permissions
dr-xr-x---.   17 root root  4096 Oct  4 12:58 root

No

Next Steps

Previous

Using the Terminal

Workshop Home

Intro to Linux CLI: The File System

Next

Summary

Page Comparison

Versions Compared

Old Version 22

New Version 23

Key

Some high-level comparison to that of Windows

Linux OS General Structure

Linux Hierarchical Structure: Example

Absolute Path: /home/arcc-t05/

Absolute Path: /home/arcc-t05/workshop/projects/p01/etc/

Relative Path: workshop/projects/p01/etc/

Relative Path: p01/etc/

Ex: Starting at / (root), what is the absolute path to the bits folder?

Answer:

Ex: Starting in the home folder what is the relative path to the Jan folder?

Answer:

Commands:

<command --help>

Commands: <command --help>

pwd: Print the name of the current working directory

cd: Change the shell working directory

cd: Change working directory (cont)

Answer:

cd: Change the shell working directory

Answer:

ls: List information about the FILEs (cwd by default)

mkdir: Create the DIRECTORY(ies), if they do not already exist

mkdir: Create the DIRECTORY(ies), if they do not already exist

mv: Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

mv: Rename SOURCE to DEST, or move SOURCE(s) to DIRECTORY

cp: Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY

cp: folders

rmdir: Remove the DIRECTORY(ies), if they are empty

rm: Remove (unlink) the FILE(s)

rm: Remove (unlink) the FILE(s)

rm: folders and file(s)

rm: WARNING

history

Exercises

Answers

File Ownership and Permissions

File Ownership and Permissions

Permission Denied

If we change directories, and go to /project/arccanetrain/intro_to_linux, what permissions do the contents of this directory have?

Exercise: Try it

Answers

Next Steps