• Within this and following sections, we have tried to make the descriptions and examples generic.

• If you are following along as part of a scheduled training or bootcamp, where you see <project-name> replace this with the project name being used for the workshop (which changes) and <username> with your username.

• Also, the hostname that you might see might change depending on the cluster you’re using.

• 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.

/usr/include/bits/

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

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Commands are 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).

The next couple of parts list and briefly summarize the commands we will be covering within this section:

pwd, cd, ls, mkdir, mv, cp, rmdir and rm.

We will then follow up with examples on how to use them.

$ cd
[~]$ ls
Desktop  Documents  Downloads
[~]$ mkdir folder01
[~]$ ls
Desktop  Documents  Downloads  folder01

Try creating that folder again. What happens?

[~]$ mkdir folder01
mkdir: cannot create directory ‘folder01’: File exists
exists

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

Navigate into this folder and print the current working directory.

[~]$ cd folder01/
[folder01]$ pwd
/home/arcc-t05<username>/folder01

Within folder01, try creating two new folders called folder02 and folder03.

Navigate into folder02 and print the current working directory.

Notice: You can create multiple folders at the same time.

Renaming a file is the same as moving it to a new name.

Navigate to your home and create a file called myfil.txt

Move this file from myfil.txt to myfile.txt.

[~]$ mv myfil.txt myfile.txt 
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile.txt

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

Notice how we used ls to see what is in a relative folder.

[]$ cd
[~]$ touch myfile02.txt
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile02.txt

# Copy 

Copy (duplicate)

this file to a

new file

called myfile02b.txt.

[~]$ cp myfile02.txt myfile02b.txt 
[~]$ ls
Desktop  Documents  Downloads  folder01  myfile02b.txt  myfile02.txt

# Copy a file into an existing folder.

Copy file myfile02b.txt into the existing folder02 folder.

[~]$ cp myfile02b.txt folder01/
[~]$ ls folder01/
folder02  folder03  myfile02b.txt  myfile.txt

Navigate home and try copying the folder01 folder.

The rmdir command can only be used to remove an empty directory.

Look at one way at removing a folder that itself contains folders and files.

This has taken a lot of individual steps.

Can we do this quicker?

Take a further look at the rm command.

Alternatively we could have removed the above 2 files with: rm myfile*

The * character is a wildcard, so the rm myfile* will remove all starting with the characters myfile

You can repeat a command. Lets repeat the command labelled 223:

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

Questions:

1. How can you return to your home folder?

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

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

4. Go back through the command related slides are try for yourself.

1: How can you return to your home folder?

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

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

What does the output of ls –l mean?

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

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

-rw-rw-r--    1 <username> <project-name>     26 Oct  5 07:20 workshop_all.txt

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

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

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

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

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

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

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

Any user within the <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?

[] ls -al
# -rw-------    1 arcc<arcc-t05username> arccanetrain<project-name>     2623 Oct  5 07:20 workshop_all.txt

Only user <arcc-usernameusername> can read/write this file. No one else, not even anyone within the <project-name> group, can view this file.

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

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

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

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

4. Can you cd into the /opt folder?

5. Can you cd into the /root folder?

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

<username>
[<username>]$ touch test.txt
# Do you get a “Permission denied”?

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

#

drwxr-

sr-x 

2 

2. Can you /project/<project-name>/intro_to_linux

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

4. Can you cd into the /opt folder?

[<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.

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

5. Can you cd into the /root folder?