...

Is there a difference between running ls versus ls -al?
How can you find out what the –al options do?
What does the pwd command do?
From the command line, what happens if you press the up/down arrow keys?

...

02.11 Answers

1: Is there a difference between running ls versus ls -al?

Code Block

[arcc-t05@blog1 ~]$ ls
Desktop  Documents  Downloads

[arcc-t05@blog1 ~]$ ls -al
total 76
drwxr-x---   8 arcc-t05 arcc-t05  4096 Oct  3 13:57 .
drwxr-xr-x 925 root     root     32768 Sep 27 16:21 ..
-rw-------   1 arcc-t05 arcc-t05   212 Sep 12 15:44 .bash_history
-rw-r--r--   1 arcc-t05 arcc-t05    18 Aug 10 17:00 .bash_logout
-rw-r--r--   1 arcc-t05 arcc-t05   141 Aug 10 17:00 .bash_profile
-rw-r--r--   1 arcc-t05 arcc-t05   376 Aug 10 17:00 .bashrc
drwx------   3 arcc-t05 arcc-t05  4096 Sep 12 11:36 .config
drwxr-xr-x   2 arcc-t05 arcc-t05  4096 Aug 10 17:00 Desktop
drwxr-xr-x   2 arcc-t05 arcc-t05  4096 Aug 10 17:00 Documents

...

02.12 Answers

2: How can you find out what the –al options do?

Use man ls or ls --help
-a, --all do not ignore entries starting with .
-l use a long listing format

Options are also case sensitive:

Code Block
[arcc-t05@blog1 ~]$ ls -A .bash_history .bash_profile .config Documents .emacs .kshrc .mozilla .zshrc .bash_logout .bashrc Desktop Downloads .esd_auth .lesshst .sshWhat does the pwd command do?

3: What does the pwd command do?

Use man pwd or pwd --help
pwd - print name of current/working directory

4: From the command line, what happens if you press the up/down arrow keys?

Steps through the previous commands you’ve typed.

...

Code Block

# Reset: cd
# Move up one level.
# Move into the folder’s parent.
[arcc-t05@blog1 ~]$ cd ..
[arcc-t05@blog1 ~]$ pwd
/home

[arcc-t05@blog1 home]$ cd ..
[arcc-t05@blog1 /]$ pwd
/
# In the ‘root’ folder
[arcc-t05@blog1 /]$ ls

# Are we defining an absolute 
# or relative path?
[arcc-t05@blog1 /]$ cd opt
[arcc-t05@blog1 opt]$ pwd
/opt

Code Block

# Change back to home.
[arcc-t05@blog1 opt]$ cd
[arcc-t05@blog1 ~]$

# Are we defining an absolute 
# or relative path?
[arcc-t05@blog1 ~]$ cd /usr/include/asm
[arcc-t05@blog1 asm]$ pwd
/usr/include/asm

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

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

...

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

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

Headers and Sections

...

Code Examples

...

Two Column Tables are nice ways to separate content/ Background info along with a code example on the same “Slide”. Please notice the table width. This should stop scroll bars from appearing

Bullets are nice to include for distinct points
yep
they
sure
are
This is 14 lines

...

Code Block

Please use the "code snippet" in the + button when creating code examples. 
Also please do not go past the width of the table. 
This is to prevent scroll bars appearing This is the Max number of code lines to show an example

Straight Code - No context

Code Block
Limit to 16 lines in the example. This is the end

Same Thing With Images

...

Two Column Tables are nice ways to separate content/ Background info along with an image example on the same “Slide”. Please notice the table width. This should stop scroll bars from appearing

Bullets are nice to include for distinct points
yep
they
sure
are
This is 14 lines

...

Alternatively No Table

...

Finally The End

...

Link to Previous sub-module or Home Module

...

03.16 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

# Move the file ‘myfile.txt’ into the directory ‘folder01’
[~]$ mv myfile.txt folder01/

[~]$ ls
Desktop  Documents  Downloads  folder01

# We can ‘ls’ what is in a relative folder.
[~]$ ls folder01/
folder02  myfile.txt

...

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

Code Block

$ 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

...

03.18 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’

# “recursively” copy a folder and all its contents.
[~]$ cp –r folder01 folder03
[~]$ ls
Desktop  Documents  Downloads  folder01  folder03 myfile02b.txt  myfile02.txt

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

...

03.19 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

...

03.20 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

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?

...

03.21 rm: folders and file(s)

Code Block

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

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

[~]$ rm -r folder01/
[~]$ ls
Desktop  Documents  Downloads  myfile02b.txt  myfile02.txt

# Can remove multiple files.
[~]$ rm myfile02b.txt myfile02.txt 
[~]$ ls
Desktop  Documents  Downloads

...

03.22 rm: WARNING

From the command-line there is NO trash bin.

Using rm/rmdir is FINAL!

...

03.23 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

...

03.24 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.

...

03.25 Answers

1: How can you return to your home folder?

Use: cd or cd ~

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

Use: pwd

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

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

...

03.26 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.

...

03.27 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.

...

03.28 Permission Denied

Code Block

[]$ cd /project/arccanetrain/
# drwxr-sr-x    2 arcc-t01 arccanetrain   4096 May 16 16:26 arcc-t01
# No one other than arcc-t01 has permission to write within this folder.
[arccanetrain]$ cd arcc-t01/

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

[arcc-t01]$ cd ../intro_to_linux
# -rw-rw-r--    1 arcc-t05 arccanetrain     26 Oct  5 07:20 workshop_all.txt
# Anyone within the group can read/write this file.
[intro_to_linux]$ cat workshop_all.txt
Everybody can read this.

# Only arcc-t05 can read/write this file.
# -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

...

03.29 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.

...

03.30 Answer

Code Block

# Can you cd into the /opt folder?
[arcc-t05@blog1 ~]$ cd /opt
[arcc-t05@blog1 opt]$

# Can you cd into the /root folder?
[arcc-t05@blog1 ~]$ cd /root
-bash: cd: /root: Permission denied

# Justify your answer.
[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

Versions Compared

Old Version 6

New Version 7

Key

Headers and Sections

Code Examples

Straight Code - No context

Same Thing With Images

Alternatively No Table

Finally The End

Page Comparison

Versions Compared

Old Version 6

New Version 7

Key

Headers and Sections

Code Examples

Straight Code - No context

Same Thing With Images

Alternatively No Table

Finally The End