Using sed - Part 2

Each team member must complete this assignment individually in his or her own it341 directory.

This project will not be done on your virtual machine.

Instead, it will be done on users.cs.umb.edu.

When I say "script" in this assignment, I am referring to something very different from the script utility, as used in Assignment #3.

The first line of each script file should be a "shebang" line:
#!/bin/bash
To make file changes in place, use sed with the -i option. Example:
                sed -i 's/Roses/Poinsettias/' roses.txt
Rather than printing the change to standard output, it will change the file itself.
To create a backup when changing a file, specify an extension for the backup file with the -i option. Example:
                sed -i.bak 's/Roses/Poinsettias/' roses.txt
In addition to changing the file, the new file roses.txt.bak will contain the file's old contents.
My grading process will include the following:

Copy pristine file copies into a folder.

Print the text of your script files.

Run the scripts.

Print the text files to verify their contents have changed.

You may see (a variation of) my grading script at the bottom of this page.

For another example, see the file roses_example.pdf

To be sure that these scripts work, you will likely need to run and test them multiple times. Each time, you should download new copies of the text files before testing your scripts.

NOTE: This assignment assumes that you are familiar with the process of writing and running bash scripts.
Log in to users.cs.umb.edu
You will need an ssh client to do this.
Go to your it341 directory
    cd it341
Create a directory for this assignment
    mkdir assign4
Go to your assign4 directory
    cd assign4
Copy practice files to this directory
    cp  /home/ckelly/course_files/it341_files/{interfaces,hosts,passwd} .
The scripts you will write below will operate on the files you have just copied.
Create script files in this directory
    touch {interfaces,hosts,passwd}_update.sh
Do a long listing to confirm that script files exist:
    ls -l *_update.sh
Make script files executable:
    chmod 750 *_update.sh
Open the shell script interfaces_update.sh for editing:
The first line of your shell script should be the hashbang line: #!/bin/bash

Next, add sed commands that will make the following modifications to the interfaces file you have just copied
Change the line
    iface  eth0  inet  dhcp
to read
    iface  eth0  inet  static
Add the following after this line
    network  10.0.0.0
    address  10.0.0.201  
    gateway  10.0.0.1
    broadcast  10.0.0.255
    netmask  255.255.255.0
    dns-nameservers  10.0.0.1
If you need to debug/troubleshoot your shell script, please re-copy the interfaces from /home/ckelly/course_files/it341_files so that you have a fresh copy to test against.
Open the shell script hosts_update.sh for editing:
The first line of your shell script should be the hashbang line: #!/bin/bash

Next, add sed commands that will add the following lines to hosts
    # Gateway
    10.0.0.1    it20.it.cs.umb.edu  it20
    
    # Addresses for the Windows PCs
    10.0.0.240  it21.it.cs.umb.edu it21
    10.0.0.241  it22.it.cs.umb.edu it22
    10.0.0.242  it23.it.cs.umb.edu it23
    10.0.0.243  it24.it.cs.umb.edu it24
    10.0.0.244  it25.it.cs.umb.edu it25
    10.0.0.245  it26.it.cs.umb.edu it26
    10.0.0.246  it27.it.cs.umb.edu it27
    10.0.0.247  it28.it.cs.umb.edu it28
If you need to debug/troubleshoot your shell script, please re-copy the hosts from /home/ckelly/course_files/it341_files so that you have a fresh copy to test against.
Open the shell script passwd_update.sh
The first line of your shell script should be the hashbang line: #!/bin/bash

Next, add sed commands that will modify the line
    sysadmin:x:1000:1000:sysadmin,,,:/home/sysadmin:/bin/bash
so it reads
    sysadmin:x:1000:1000:sysadmin,,,:/home.it20/sysadmin:/bin/bash
NOTE: Multiple lines in the passwd file may contain home, but your script should be written so that it is changed ONLY on the line for sysadmin. If you need to debug/troubleshoot your shell script, please re-copy the passwd from /home/ckelly/course_files/it341_files so that you have a fresh copy to test against.

Script Behavior Example:

The following images are intended to illustrate how your scripts would behave. The example I am using here will involve the files interfaces and interfaces_update.sh

This just shows an example of you creating your directory for this assignment, changing into it, and copying over the relevant files:
Editing interfaces_update.sh and setting the permissions to 750. You may have already set the permissions to 750, before editing, in which case you would not need to set them again:
This shows what the interfaces file would look like before running the interfaces_update.sh script -- and after. Notice how the file-size and the last-modified date on the interfaces file have changed!
This shows the contents of the interfaces file, which you see has changed as a result of running the interfaces_update.sh script:

Grading Script:

(This is not the exact script I will use, but it is a good indicator of how one should be able to run your script.)

#!/bin/bash


# Each iteration or repetition of this loop represents 
# the process of grading ONE student's work

for student in `ls ~/it341`
do
    
    # Here, I bring in pristine copies of the text
    # files, copy over your script files, and 
    # and make them executable

    mkdir $student
    cd $student
    cp /home/ckelly/course_files/it341_files/* .
    cp ~/it341/$student/assign4/*.sh .
    chmod 755 *.sh

    # Check, print, and run interfaces_update.sh

    ls -l interfaces_update.sh
    cat interfaces_update.sh
    echo Running interfaces_update.sh
    ./interfaces_update.sh

    # Confirm that expected changes were made to
    # the interfaces file

    ls -l interfaces
    cat interfaces

    # Check, print, and run hosts_update.sh

    ls -l hosts_update.sh
    cat hosts_update.sh
    echo Running hosts_update.sh
    ./hosts_update.sh

    # Confirm that expected changes were made
    # to the hosts file

    ls -l hosts
    cat hosts

    # Check, print, and run passwd_update.sh

    ls -l passwd_update.sh
    cat passwd_update.sh
    echo Running passwd_update.sh
    ./passwd_update.sh

    # Confirm that expected changes were made
    # to the passwd file

    ls -l passwd
    cat passwd

done