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Panel

panelIconId	1f642
panelIcon	:slight_smile:
panelIconText	🙂
bgColor	#FFEBE6

If you are following along as part of a scheduled training or bootcamp, please replace the arccanetrain <project-name> 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.

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

Code Block
[arcc-t05@blog1<username>@blog1 ???]$ cd [arcc-t05@blog1<username>@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<username>@blog1 ~]$ pwd /home/arcc-t05<username>

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cd: Change the shell working directory

Info
Start by navigating back to home.

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

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

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

Info
Move up another level into the root folder.

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

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cd: Change working directory (cont)

Info
Navigate into the `opt` folder.

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

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

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Info
First reset back to home.

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

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

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

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Info
Navigate up two levels:

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

Info
Navigate back home:

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

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

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Info
List files in the user’s home folder.

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

Info
List long format that includes ownership and permission details.

Code Block
[arcc-t05@blog1<username>@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<username>@blog1 ~]$ ls –a

Info
List all files with long format.

Code Block
[arcc-t05@blog1<username>@blog1 ~]$ ls –al

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

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

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

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

Info
Note how we can use multiple options together.

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

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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<username>/folder01

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

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Code Block

[folder01]$ mkdir folder02 folder03
[folder01]$ ls
folder02 folder03
[folder01]$ cd folder02/
[folder02]$ pwd
/home/arcc-t05<username>/folder01/folder02
[folder02]$ cd ../..
[~]$ pwd
/home/arcc-t05<username>

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

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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"

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rm: WARNING

From the command-line there is NO trash bin.!

Using rm/rmdir is FINAL!

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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<username>@blog1 ~]$ !223
ls
Desktop  Documents  Downloads

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Exercises

Info

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.

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Answers

Info
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

Info
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.

Info
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.

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File Ownership and Permissions

Info
What does the output of `ls –l` mean?

Code Block

[arcc-t05@blog1<username>@blog1 ~]$ cd /project/arccanetrain<project-name>/intro_to_linux
[arcc-t05@blog1<username>@blog1 intro_to_linux]$ ls -al
total 54
drwxrwsr-x  4 salexan5<someuser> arccanetrain<project-name>  4096 Oct  6 08:09 .
drwxrws--- 40 root     arccanetrain  <project-name>  4096 Oct  6 08:09 ..
drwxrwsr-x  2 salexan5<someuser> arccanetrain<project-name>  4096 Oct  5 11:19 clusters
drwxrwsr-x  6 salexan5<someuser> arccanetrain<project-name>  4096 Oct  5 14:56 data
-rw-rw-r--  1 salexan5<someuser> arccanetrain<project-name>   874 Oct  5 15:30 fruits.txt
-rw-rw-r--  1 salexan5<someuser> arccanetrain<project-name> 34472 Oct  5 10:57 software.csv
-rw-rw-r--  1 salexan5<someuser> arccanetrain<project-name>  1603 Oct  6 08:08 vegatables.txt
-rw-rw-r--  1 arcc<someuser> <project-t05name> arccanetrain    26 Oct  5 07:20 workshop_all.txt
-rw-------  1 <someuser> arcc<project-t05name> arccanetrain    23 Oct  5 07:20 workshop_me.txt

Info
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.

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File Ownership and Permissions

Code Block
-rw-rw-r-- 1 <username> arcc<project-t05name> arccanetrain 26 Oct 5 07:20 workshop_all.txt

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User: This is the owner of the file/folder. By default, the person who created it becomes its owner.
- arcc-t05 is <username> 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 <project-name> is the group.
- All In general, for a workshop, all attending users / the arcc-txx users (if being used) 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.

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

Code Block
[]$ cd /project/arccanetrain<project-name>/ []$ ls -al ... # drwxr-sr-x 2 arcc<username> <project-t01name> arccanetrain 4096 May 16 16:26 arcc-t01<username> ...

Info

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

Try navigating into a <different-username> folder within <project-name> and creating a file.

Code Block

[arccanetrain<project-name>]$ cd arcc<different-t01username>/
# Can arcc-t05<username> create (write) a file within this folder?
[arcc<different-t01username]$ touch text.txt
touch: cannot touch 'text.txt': Permission denied

Note
No one, other than `arcc<different-t01username>` can create (write) a file within this folder.

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If we change directories, and go to /project/

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<project-name>/intro_to_linux, what permissions do the contents of this directory have?

Code Block
[arcc-t01<username>]$ cd ../intro_to_linux [arcc-t01<username>]$ ls -al # -rw-rw-r-- 1 arcc<arcc-t05username> arccanetrain<project-name> 26 Oct 5 07:20 workshop_all.txt

Info

Any user within the arccanetrain <project-name> 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<arcc-t05username> arccanetrain<project-name> 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<arcc-t05usernameusername>` can read/write this file. No one else, not even anyone within the `arccanetrain` `<project-name>` group, can view this file.

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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

Info

Questions: In all cases be able to justify your answer.

Can you create a folder under /project/<project-name>/username>/?
Can you /project/<project-name>/intro_to_linux/ and view workshop_all.txt?
Can you /project/<project-name>/intro_to_linux/ and view workshop_me.txt?
Can you cd into the /opt folder?
Can you cd into the /root folder?

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Answers

Info
1. Can you create a folder under `/project/<project-name>/username>/`?

Expand

title	Answer

Code Block
[]$ cd /project/<project-name>/ [<project-name>]$ cd <username> [<username>]$ touch test.txt # Do you get a “Permission denied”?

Yes. You should have write permissions as owner for this folder.

Code Block
# drwxr-sr-x 2 <username> <project-name> 4096 May 16 16:26 <username>

Info
2. Can you `/project/<project-name>/intro_to_linux/` and view `workshop_all.txt`?

Expand

title	Answer

Code Block
[<username>]$ cd ../intro_to_linux [intro_to_linux]$ cat workshop_all.txt # Do you get a “Permission denied”?

Yes. Everybody can read this.

Code Block
-rw-r--r-- 1 <arcc-username> <project-name> 26 Sep 4 10:38 workshop_all.txt

Info
3. Can you `/project/<project-name>/intro_to_linux/` and view `workshop_me.txt`?

Expand

title	Answer

Code Block
[intro_to_linux]$ cat workshop_me.txt # Do you get a “Permission denied”?

No. Only <arcc-username> can read/write this file.

Code Block
-rw------- 1 <arcc-username> <project-name> 23 Sep 4 10:38 workshop_me.txt

Info
4. Can you `cd` into the `/opt` folder?

Expand

title	Answer

Code Block
[<username>]$ cd /opt [<username> opt]$ # “other” has read permissions drwxr-xr-x. 5 root root 43 Jun 26 11:47 opt

Yes. The other has read permissions.

Code Block
drwxr-xr-x. 5 root root 43 Jun 26 11:47 opt

Info
5. Can you `cd` into the `/root` folder?

Expand

title	Answer

Code Block

[arcc-t05@blog1 ~<username>]$ cd /root
-bash: cd: /root: Permission denied
[arcc-t05@blog1 ~<username>]$ ls -l /
...
# “other” has No permission set for other read permissions
drwxrdr-xr-x---.   17 5 root root  4096 Oct 43 Jun4 26 1112:47 opt
...
# No permission set for other read permissions
58 root

No. There are no permissions set for other read permissions.

Code Block
dr-xr-x---. 17 root root 4096 Oct 4 12:58 root

No

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Next Steps

Previous

Using the Terminal

Workshop Home

Intro to Linux CLI: The File System

Next

Summary

Versions Compared

Old Version 23

New Version 24

Key

cd: Change the shell working directory

cd: Change working directory (cont)

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

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

rm: WARNING

history

Exercises

Answers

File Ownership and Permissions

File Ownership and Permissions

If we change directories, and go to /project/

<project-name>/intro_to_linux, what permissions do the contents of this directory have?

Exercise: Try it

Answers

Answers

Next Steps

Page Comparison

Versions Compared

Old Version 23

New Version 24

Key

cd: Change the shell working directory

cd: Change working directory (cont)

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

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

rm: WARNING

history

Exercises

Answers

File Ownership and Permissions

File Ownership and Permissions

If we change directories, and go to /project/

<project-name>/intro_to_linux, what permissions do the contents of this directory have?

Exercise: Try it

Answers

Answers

Next Steps