Tutorial6: File Transfer / Sending Email Messages

From CDOT Wiki
Jump to: navigation, search

TRANSFERRING FILES BETWEEN COMPUTERS


Main Objectives of this Practice Tutorial

  • List common utilities contained in the ssh application framework
  • Securely copy files between Unix/Linux servers using the scp command
  • Securely transfer copies of files between Unix/Linux servers using the sftp command
  • Use the ssh command to run and view commands on a remote computer from a local computer.
  • Use the mail command to send email with file attachments to your Seneca email account


Tutorial Reference Material

Course Notes
Definitions / Commands
YouTube Videos
Course Notes: Definitions: File Transfer Commands: Instructional Videos:

KEY CONCEPTS

The ssh Linux command is a suite of tools to allow the user to issue Linux commands securely between
Unix / Linux servers, as well as securely copy and transfer files among Unix/Linux servers.

In this tutorial, you will learn several different methods to securely transfer files from your Matrix Linux account
to other computers using Linux commands including scp, sftp and mail.


Issuing Commands on Remote Unix/Linux Servers

The ssh command can be used to run and view commands on remote computer from a local computer.

You can use the ssh command to issue Unix/Linux commands on a remote server
from your local computer without logging into a remote server (such as Matrix).


Command Usage:

ssh username@matrix.senecacollege.ca ls -l

You will be prompted for your Matrix account password, then the contents of your home directory in your remote Matrix account will be displayed on your local computer's terminal.

Secure Copy (scp)

The scp Unix/Linux command is used to securely copy files between Unix/Linux servers.

The scp command is used to securely copy files between your local computer and remote Unix/Linux server. The usage for the scp command is similar to the cp command with the addition of user name and host name.


Command Usage:

scp local.file username@host:destination-pathname
scp local.file username@host:
scp user@host:file-pathname local-pathname

The most common mistake that students make is forgetting to add
the colon character ":" after the remote hostname.

The user name in the command can be omitted if it's the same as on the local host.
Multiple file and recursive directory copy (i.e. option -R) is supported.

Secure File Transmission Control Protocol (sftp)

The sftp Unix/Linux command is used to securely transfer (copy) files between Unix/Linux servers.

FTP stands for File Transfer Protocol which provides a set of rules on how to convert data that is transferred between computers (both identical and different operating systems). The sftp command performs file transfers securely using encryption.


Command Usage:

sftp username@hostname


When you login via the sftp command, the sftp prompt appears. The sftp prompt is like a Bash shell prompt, but with a limited number of commands. When issuing sftp commands, the local server relates to the server where you first issued the sftp command. Refer to the diagram on the right for local and remote sftp commands.

Graphical SFTP application.


Graphical SFTP Applications

Although it is important to know how to use the sftp command for quizzes, midterm and final exam,
there are graphical sftp applications that provide an alternative to issuing commands.

If you installed the graphical Secure Shell Client application in your Windows computer from performing TUTORIAL 1 INVESTIGATION 1, you can use this application to transfer files between your computer and your Matrix account by graphically navigating, selecting and dragging files between computers.

Sending Emails with File Attachment (mail)

You can use the mail command in Matrix to send email messages
to other email accounts via the Internet.


Using the mail command with redirection to send email
with file attachment.

Sending a Simple Email Message:

  1. Type: mail username@hostname and press ENTER
  2. Enter subject line and press ENTER
  3. Type the body of the message and then when finished,
    press ctrl+d to send message

Sending an Email Message with a File Attachment:

Viewing email with file attachment in
Seneca email account.
  1. Type: mail username@hostname -a filepathname and press ENTER
  2. Enter subject line and press ENTER
  3. Type the body of the message and then when finished, press ctrl+d to send message

Alternative Method of Sending an Email Message with a File Attachment:

  1. Type: mail -s "subject line" username@hostname < filepathname
  2. Press ENTER to send

    NOTE: You would have to use this method since you have used stdin redirection
    to attach the file’s so you can’t input the subject line from the terminal!

INVESTIGATION 1: FILE TRANSFER (SECURE COPY)

ATTENTION: This tutorial will provide additional practice with the necessary skills for completing this weeks segment of your assignment and is not worth marks.

Make certain to open a command-line terminal and
NOT a graphic SSH application for this tutorial!.

The SSH package on your home computer and on the Matrix Linux server
contain a suite (i.e. collection) of secure utilities including ssh and scp.


In this investigation, you will learn how to use the scp command to securely copy files between your computer and your Matrix Linux server. This methods is useful because it can be performed in the MS-Windows, MacOSx, and Unix/Linux operating systems.

You will also learn how to issue the ssh command to run commands on your
remote Matrix server while remaining on your local computer.


Perform the Following Steps:

  1. Determine which operating system that your computer is using.

  2. Connect to your Matrix account using the instructions in the table below based on your current operating system.

Newer Version of Windows 10: MacOSX: Linux:
  • From the start menu, type cmd and launch program
  • In the command terminal, enter the following command:
    ssh senecausername@matrix.senecacollege.ca
  • Click Launchpad icon, type terminal
    and press ENTER
  • In the terminal, enter the following command:
    ssh senecausername@matrix.senecacollege.ca
  • From the menu, choose:
    Applications > System Tools > Terminal
  • In the terminal, enter the following command:
    ssh senecausername@matrix.senecacollege.ca

  1. NOTE: Make certain to open a command-line terminal and NOT a graphical SSH application for this tutorial.

  2. After logging into your Matrix account, issue to the pwd command to confirm you are in your home directory.

  3. Issue the following Linux command to create the following directory:
    mkdir ~/remote

  4. Change to the ~/remote directory and confirm that you have changed to that directory.

  5. Use a text editor to create a text file called myfile.txt

  6. Enter the following two lines displayed below in your editing session:
    This is my file
    It is a small file


  7. Save editing changes to your myfile.txt file and exit your text editor.

  8. Let's run a shell script to check that you created the remote directory
    and that you created the myfile.txt file (with correct file contents) in that directory.

  9. Enter the following command: ~uli101/week6-check-1

  10. If you encounter errors, make corrections and then re-run the checking script until you receive
    a congratulations message, and proceed to the next step.

    NOTE: We will now learn to transfer files between your local home computer and your remote Matrix Linux server.

You are required to remain in your local computer's command terminal for the remainder of this INVESTIGATION and INVESTIGATION 2
  1. Exit your Matrix ssh session but remain in the command terminal
    on your local computer..

    ATTENTION: You are required to remain in your local computer's command terminal for the remainder of this INVESTIGATION and INVESTIGATION 2.

  2. The mkdir command works with MS Windows/UNIX/Linux/MacOSx computers.
    Issue the following command on your local computer to
    create a directory called local: mkdir local

  3. The cd command works with MS Windows/UNIX/Linux/MacOSx computers.
    Issue the following command on your local computer to
    change to the local directory: cd local

  4. If you are using MS Windows on your local computer, issue the dir command to confirm you are
    in the local directory; otherwise, use the pwd command.

  5. If you are in MS Windows, open the GRAPHICAL NotePad application to create a text file
    (Otherwise, use the nano or vi text editor).

  6. Enter a few lines of text, and if using Notepad, then click on the File menu and select save as
    (save as the filename other.txt in your local directory) and then exit the Notepad text editor.

    NOTE: if using another text editor, save your editing session and exit the text editor.

  7. If your OS is MS Windows issue the dir Windows command to view the contents of your current directory
    (otherwise, issue the ls command for other operating systems).

    We will use the scp command to copy the local file called other.txt to your home directory on your remote Matrix Linux server.

  8. Issue the following Linux command to copy the other.txt file from your local machine to your remote Matrix server
    (replace yoursenecaid is YOUR Seneca ID and ADD A COLON : TO THE END OF THE COMMAND):
    scp other.txt yoursenecaid@matrix.senecacollege.ca:

  9. When prompted, enter your Matrix password.
    You can issue the ssh command, followed by a command that will be run on your remote computer,
    but display command output on your local computer.

    TIP: You can issue the ssh command, followed by a command that will be run on your remote computer, but display on your local computer without having to establish a continuous connection to your remote Matrix server.

  10. Issue the following command (using your matrix username):
    ssh yoursenecaid@matrix.senecacollege.ca ls -l other.txt

  11. When prompted, enter your password and press ENTER.

    Do you see detailed information other.txt file? (look at bottom)
    That command was run remotely on your Matrix server as confirmation that you securely copied that file to the home directory of the Matrix server.

    Let's copy the file called myfile.txt in the ~/remote directory that you created earlier in your Matrix account to your local directory on your home computer.

  12. Issue the following Linux command (replace yoursenecaid is YOUR Seneca ID).
    The period "." as second argument represents your current directory
    on your local computer):
    scp yoursenecaid@matrix.senecacollege.ca:remote/myfile.txt .

  13. Issue the dir or ls command (depending on the OS of your local computer) to confirmed your properly copied that file from Matrix.

  14. Use the Notepad application (or vi for other OS types) to create a text file called mytextfile.txt,
    type some text and then save in the local directory of your computer.

  15. Issue the dir or ls command (depending on your OS) to confirm that your newly-created file exists in your local directory.

  16. We are going to intentionally make a mistake with the scp command.
    Issue the following Linux command to copy the mytextfile.txt file from your local machine to your remote Matrix server
    (replace yoursenecaid is YOUR Seneca ID and DO NOT INCLUDE THE : at the end of the command so see what happens):
    scp mytextfile.txt yoursenecaid@matrix.senecacollege.ca

    Did you notice anything different (i.e. no password)?

  17. Issue the following command (using your matrix username):
    ssh yoursenecaid@matrix.senecacollege.ca ls -l mytextfile.txt

  18. When prompted, enter your password and press ENTER.

    The file mytextfile.txt does NOT appear in your home directory on your Matrix server!
    Note that the COLON was NOT added to the end of the command! Therefore, you MUST
    remember to include the COLON : at the end of the hostname, or it will NOT remotely copy the file!


  19. Issue the following command to properly copy that same file to your Matrix server:
    scp mytextfile.txt yoursenecaid@matrix.senecacollege.ca:

  20. Issue the following command to confirm that it was remotely copied to your home directory in Matrix:
    ssh yoursenecaid@matrix.senecacollege.ca ls -l /home/yoursenecaid/mytextfile.txt

    Do you see the output for the detailed file listing of mytextfile.txt?
    What does this indicate?

  21. Issue the following command to copy the other.txt file on your local computer to the ~/remote directory in Matrix renaming it as different.txt:
    scp other.txt yoursenecaid@matrix.senecacollege.ca:remote/different.txt

  22. Issue the following command to confirm that the file was remotely copied to your ~/remote directory in Matrix with a different filename:
    ssh yoursenecaid@matrix.senecacollege.ca ls -l /home/yoursenecaid/remote/different.txt

    Were you able to properly copy this file?

    Let's issue a checking script remotely to see that you properly copied that file from your
    local computer to your remote Linux server to both your home directory and ~/remote directory.

  23. Issue the following:
    ssh yoursenecaid@matrix.senecacollege.ca ~uli101/week6-check-2

    If you encounter errors, re-run the scp commands to correct and re-run the above command until you receive a congratulations message.

  24. Remain in the terminal on your local computer and proceed to INVESTIGATION 2.

In the next investigation, you will use the sftp Linux command to transfer (i.e. copy) files between your local computer and the Matrix server.


INVESTIGATION 2: FILE TRANSFER (SECURE FTP)

The SSH package on your home computer and on the Matrix Linux server
contain a suite (i.e. collection)of secure utilities including ssh and sftp.


In this investigation, you will learn how to use the sftp command to transfer files between
Unix/Linux servers. This methods is useful because it can be performed in the
MS-Windows, MacOSx, and Unix/Linux operating systems.

You will also learn how to issue the ssh command to run commands on your
remote Matrix server while remaining on your local computer.


Command Line Terminal (CLI)

Let's look at using the sftp command on your local machine.


Perform the Following Steps:

Make certain to remain in the
command-line terminal in your local computer.
  1. Make certain that you are in a command terminal on your local computer
    (i.e. do NOT log into your Matrix account).

  2. Issue a command (depending on your OS) to confirm that you are located in the local directory in your home computer.

  3. If you are in MS Windows, open the NotePad application to create a text file
    (otherwise: use another text editor like vi or nano)
    .
  4. Enter a few lines of text, and then click on the File menu and select save as
    (save as the filename thefile.txt in your local directory) and then exit the Notepad text editor.

    If you using another OS, then save-as using the same filename and directory location for the text editor you are using.

  5. If your OS is MS Windows issue the dir Windows command to view the contents of your current directory
    (otherwise, issue the ls command for other operating systems).

    Note: the relative pathname symbols "." and ".." work for the Windows/MacOSx/Unix/Linux operating systems.

  6. Issue the following command to move to the parent directory: cd ..

  7. If your OS is MS Windows issue the dir Windows command to view the contents of that parent directory that you changed to
    (otherwise, issue the ls command for other operating systems).

  8. Issue the following command to start an sftp session (note: yoursenecaid is YOUR Seneca ID):
    sftp yoursenecaid@matrix.senecacollege.ca

    NOTE: You may be required to enter yes to have the public key shared.

    Common sftp commands to manage the transfer
    of files between computers.
  9. You should be in the sftp command prompt where you are expected to issue sftp commands. Please take a moment to view common
    local and remote sftp commands on the right-side table.

  10. Issue the following sftp command: pwd

    What is the pathname? Which server does this represent: local or remote?

  11. Issue the following sftp command: lpwd

    What is the pathname? Which server does this represent: local or remote?

  12. Issue the following sftp command to create a directory on your remote server: mkdir remote2

  13. Issue the following sftp command to confirm that the remote2 directory has been created
    in your remote server's home directory:
    ls

  14. Issue the following sftp command to change to the remote2 directory on your remote server:
    cd remote2

  15. Issue the pwd sftp command to confirm that you have changed to the remote2 directory on your remote server.

  16. Issue the following sftp command to change to the local directory on your local computer:
    lcd local

  17. Issue the lpwd sftp command to confirm that you have changed to the local directory on your local computer.

  18. Issue the following sftp command to transfer the file called thefile.txt to the ~/remote2 directory on your remote server:
    put thefile.txt

  19. Issue the ls sftp command to confirmed that you transferred the file called: thefile.txt

    Let's create another directory on your local computer called local2 so we can learn to download a file from your remote directory.

  20. Issue the following sftp command to change to the parent directory on your local computer:
    lcd ..

  21. Issue the lpwd sftp command to confirm that your current working directory on your local computer is your home directory.

  22. Issue the following sftp command to create the following directory on your local computer:
    lmkdir local2

  23. Issue the following sftp command to change to the local2 directory on your local computer:
    lcd local2

  24. Issue the lpwd sftp command to confirm you have changed to the local2 directory on your local computer.

    Let's learn to download a file from your remote server to your local computer.

  25. Issue the following sftp command to transfer your thefile.txt file from the remote2 directory
    on your remote server to your local computer:
    get thefile.txt

  26. Issue the lls sftp command to confirm that you transferred the file thefile.txt to your local computer.

  27. Issue the following sftp command to exit the sftp utlilty: exit

  28. Issue the ssh command to login to your Matrix server account.

  29. Issue the following Linux command to remotely run a checking script to ensure you created the correct directories
    and properly transferred those created files:
    ssh yoursenecaid@matrix.senecacollege.ca ~uli101/week6-check-3

  30. If you encounter errors, make corrections and then re-run the checking script until you receive a congratulations message.

    FYI: To run a checking program to check if you created the local and local2 directories in MS Windows would require
    running a local-based script (like PowerShell). Since this is a Unix/Linux based course, we don't have a PowerShell script,
    so we will ignore checking for files transferred to your local computer.

Although it is important to learn how to use command-line sftp which is considered coverage for quizzes, midterm and final exam, there are graphical sftp applications available that are considered "user-friendly". The next investigation will show you how to transfer files between your local computer and your Matrix server graphically (assuming your local computer is running MS Windows).


Graphical Application (Secure Shell)

SSH Secure Shell Client has a graphical application to transfer files between computers.

If you installed the graphical Secure Shell application in TUTORIAL 1 INVESTIGATION 1,
you can run a graphical application from your computer desktop to transfer files between
your computer and your Matrix account.

Let's run the Secure Shell SFTP application to transfer files between computers.
This investigation assumes that your computer is a Windows machine. If you local computer
is NOT a Windows machine, you can skip this investigation.


Perform the Following Steps:

  1. On your local computer, open the NotePad application to create a text file.

  2. Enter a few lines of text, and then click on the File menu and select save as
    (save as the filename yourfile.txt in your local directory)
    and then exit the Notepad text editor.

    Double Click on SFTP to launch graphical application.
    Using Quick Connect to login to your Matrix Linux server.
  3. In your local computer's command terminal, make certain that you are in the local directory, and if not, change to that directory.

  4. Issue the dir command for the local directory to confirm that you created the file called yourfile.txt

  5. On your Windows desktop, point and double-click on the
    SSH Secure file Transfer application icon.

  6. The main Secure Shell SFTP application window should appear.

    FYI: This application shows files on your home computer (on the left-side) and files on your remote Matrix computer on the right-side. You will NOT see files
    for your Matrix server since you have NOT logged into the Matrix server.

  7. Click the Quick Connect button located in the Secure SFTP application window.

    NOTE: The Connect dialog box allows the user to specify the server name
    and your account name to allow you to connect to the server.

  8. Click on the textbox labelled Hostname and type the text: matrix.senecacollege.ca

  9. Click on the textbox labelled User Name and type your Seneca username
    (i.e. same as your Seneca userid).

  10. After entering the hostname and username, click the Connect button.

  11. Enter your Seneca password when prompted.

  12. When you correctly connect to your Matrix account, you should see folders
    in your remote server (i.e. Matrix server).

    Click and drag file(s) to transfer between computers.
  13. There are two sub-windows to represent your local computer on the left
    and the remote (Matrix) server on the right.

  14. In the left (local computer) window, point and double-click on your Windows
    profile name (i.e. username) and then locate and double-click on the local directory.

  15. In the right (remote Matrix server) window, navigate to the remote2 directory
    and double-click to move to that directory.

  16. In the left window, click and drag the yourfile.txt file to the right window.

  17. Check to see that the yourfile.txt file appears in the right window to confirm
    that the file has been transferred to your Matrix server.

    NOTE: You can select multiple files by using SHIFT-CLICK or CTRL-CLICK methods
    and then click and drag file selections between computers.

  18. Take a few moments to noter other buttons for both local and remote windows to
    refresh the view, delete file(s), navigate up to parent directory, etc.

  19. Click the File menu, and select Disconnect and then click OK to disconnect your sftp connection.

  20. Now that you have disconnected, close the sftp application window.

  21. Return to your command terminal on your local computer (do NOT connect to Matrix!).

  22. Issue the following Linux command to run a checking script to confirm that you transferred
    the most recently-created textfile to the remote2 directory in Matrix:
    ssh yoursenecaid@matrix.senecacollege.ca ~uli101/week6-check-4

  23. When prompted, enter your password.

  24. If you encounter errors, make corrections and then re-run the checking script until you receive a congratulations message.

In the next investigation, you will learn an alternative way to transfer a file to another computer server
by sending an e-mail message with an attached file.



INVESTIGATION 3: FILE TRANSFER (EMAIL)

The Matrix server is also an email server that can allow you to send emails messages to other email accounts.

In this investigation, you will learn how to transfer a file from your Matrix server to another computer by sending
an email message with a file attachment.


Perform the Following Steps:

  1. Make certain that you connect and login to your Matrix server and confirm that you are located in your home directory.

  2. Issue the following Linux command (using your Seneca-ID):
    mail yoursenecaid@myseneca.ca

  3. When prompted, enter the subject line: Test Message
    and press ENTER

  4. In the email message BODY section, type the following text displayed below (and press ENTER):
    This is a test email message

  5. Press ctrl-d to send your email message.

    Did any output display? What you do think EOT stands for?

  6. Launch a web-browser, login into your Seneca email account and check for new email messages.
    Did you receive the email message that you sent from your Matrix server?

    If you did NOT receive an e-mail message, check the JUNK or CLUTTER folders.
    If you still did not receive an email message, return to your terminal and re-issue the mail command
    making certain that you pressed ctrl-d instead of pressing ctrl-c

  7. Return to your terminal (i.e. Linux Bash shell) and issue the following Linux command:
    mail -a ~/remote/myfile.txt yoursenecaid@myseneca.ca

  8. When prompted, enter the subject line: Test Message with Attachment
    and press ENTER

  9. In the email message BODY section, type the following text displayed below (and press ENTER):
    This is a test email message with a file attachment

  10. Press ctrl-d to send your message.

  11. Switch to your Seneca email and check for new email messages.

    Did you receive that email message? Does the email contain a file attachment?

  12. Return to your Linux Bash shell and issue the following Linux command:
    mail yoursenecaid@myseneca.ca < ~/remote/myfile.txt

    What happened? Were you prompted for subject and could you enter text in email body?
    Did you see a file attachment as a separate file, or just text?

  13. Check your email to see if you received your email message. If you did, what do you notice regarding the subject line?

    You should have noticed that there was NO customized subject line,
    since you redirected standard input (stdin) from the file, so there was no way
    for the user to send a subject line.

    You can use the -s option, followed by text (in quotes) to specify a subject line.

  14. Return to your Linux Bash shell and issue the following Linux command:
    mail -s "email with attachment" yoursenecaid@myseneca.ca < ~/remote/myfile.txt

  15. Check your email to see if you received your email message. If you did, what do you notice this time?

  16. After completing this INVESTIGATION, perform the LINUX PRACTICE QUESTIONS at the end of the tutorial.

LINUX PRACTICE QUESTIONS

The purpose of this section is to obtain extra practice to help with quizzes, your midterm, and your final exam.

Here is a link to the MS Word Document of ALL of the questions displayed below but with extra room to answer on the document to simulate a quiz:

https://ict.senecacollege.ca/~murray.saul/uli101/uli101_week6_practice.docx

Your instructor may take-up these questions during class. It is up to the student to attend classes in order to obtain the answers to the following questions. Your instructor will NOT provide these answers in any other form (eg. e-mail, etc).


Review Questions:

  1. Write a Linux command to copy a file in the current directory called mytext.txt from your Matrix account to your account called user1
    on the Linux server domain name called tech.myserver.com to that user’s home directory.
  2. Write a Linux command similar to the previous question, but rename the file on the remote Linux server to yourtext.txt
  3. Write a Linux command to copy a file called ~/project/linux.txt to the remote server called linux.techie.org
    (your username for this remote server is the same username for your local server).

  4. Write a Linux command to connect to the username saulm for the server domain name tux.senecac.on.ca to transfer files between Linux servers.
  5. Assuming that you are connected to that server in question #4. What is the sftp command to display your current working directory on your local server?
  6. Assuming that you are connected to that server in question #4. What is the sftp command to view files in your local server?
    What is the sftp command to view files in your remote server?
  7. Assuming that you are connected to that server in question #4. What is the sftp command to download the file answers.txt from the current directory of your remote server?
  8. Assuming that you are connected to that server in question #4. What is the sftp command to upload the file questions.txt from your local server to the ~/documents/tests directory on your remote server?
  9. Assuming that you are connected to that server in question #4. What is the sftp command to quit your current session?

  10. Write a Linux command to send the attached file message.txt to the email address murray.saul@senecacollege.ca with the subject line: Important Message
  11. Create a table listing each Linux command, useful options and command purpose for the following Linux commands: scp , sftp , mail.
  12. Create a table listing each sftp commandand it's purpose.