CSCI 257: Fundamental UNIX System Administration

Class Project for Spring 2003

The goal of the class project is to provide students with practical experience to administer Linux installation and administration on a computer shared with Windows.

Laboratory Assignment 4

ASSIGNMENT DUE: 12:00 NOON, March 12, 2003.

Assignment Description:

As a system administrator you will need to do various jobs such as manage file permissions, understand how to get information about your system and use scripting to automate tasks.

Goal:

The goal of this assignment is to introduce students to /proc, file permissions, and some shell features.

Objectives:

Explore /proc a little more.
Searching for files on your system (grep, find, and locate).
Learn how to use chmod to change permissions on files
Learn how to use chown to change file ownership
Learn about the sticky bit and the SUID and GUID bits
Learn a little about the bash shell
Learn some scripting basics

Expected Outcome:

TURN-IN

Students will perform the exercises listed and provide answers
Students will create a custom .bashrc file as described below and turn it in
Students will write the getinfo script described below and turn-in a printout

Generic questions to find out what kind of system you are doing you work on

What distribution and version of Linux are you using?__________________________________
Do you have X configured on this system?____________________________________________
Do you have internet access on this system under Linux?_________________________________
What shell are you using (bash is the Linux default, type echo $SHELL )?__________________

Examining /proc a little more (you might need to su to root to do some of this stuff).

Change to the /proc directory and view the output of ls
View the output of cat /proc/cpuinfo

What is the processor number (the first line)?_________________
What is the "model name"?________________________________
What about the cache size?________________________________

View the output of ls -l /proc/kcore ( /proc/kcore gives you a window into the memory on your computer, so you can actually view the contents of memory if you cat this file).

Notice the file size of this file tells you how much RAM you have on the system in bytes.

How many bytes of RAM does your system have according to a long listing of kcore?___________________________
Use mathematics to calculate the number of bytes of RAM your system should have? (My computer has 256MB so I do the following multiplication: 256 * 1024 * 1024 = 268435456 bytes)______________________________________
Does kcore and your math give the same result?___________________________

View the output of cat /proc/meminfo

How much is swap being used or is it all free?___________________________________

What version of gcc is on your system (cat /proc/version)?____________________________
View the output of cat /proc/interrupts

The left most column gives you the interrupt number 0-15, the next column is a counter of how many times that interrupt has been called, and the right most column tells you the driver that is calling the interrupt
What is the interrupt for the timer (0-15)?______________________
What is the interrupt for the keyboard (0-15)?_________________________

What is the watch command for (type whatis watch)?________________________________________________________________
Now view the output of watch -n1 cat /proc/interrupts

What does the counter for the keyboard interrupt read?_________________________
Hold down some key like "f" for a few seconds and watch the interrupt counter for the keyboard increase.
Next try tapping one key like "f" only occasionally to see how much the interrupt counter increases with each key press. How much does it increase with one key press?________________________________
What does the -n1 option do (type man watch if you aren't sure)?)___________________________________

View the output of cat /proc/partitions to see what partitions you have on your system. Compare it to the output of the command df. Next type the command mount with no options and view its output.
Change to the directory /proc/1 this directory contains information about process with ID 1

View the output of cat environ | tr '\0' '\n' to learn something about this programs environment

What is its home directory?______________________
What happens when you just cat environ?_____________________
What does the command tr do?______________________________

View the output of cat status

What is the name of this process?_____________________________
What state is it in?_________________________________________

View the output of the command scanpci -v | more

How many times do you see "card unknown" or "device unknown"?______________________________
Compare the output of scanpci -v | more to the output of cat /proc/pci, similar?__________________________________________
Also view the output of lspci, similar?______________________________________________________

Searching (you might need to su to root to do some of this stuff).

(When you su to root you might need to type "su -" so that your PATH gets set up right. Adding the dash makes it behave as a login shell).

The grep command

Search /etc for files containing your username, in my case I would type grep "todd" /etc/*

What files have your user name in them?________________________________________________

Do the search again but this time recursively search within all directories found inside /etc, in my case I would type grep -r "todd" /etc/*

Name any additional files with your username in them (or say none)?_____________________________ ______________________________________________________________________________________

This time just search the passwd file for your username, in my case I would type grep "todd" /etc/passwd

What is the output?______________________________________________________________________

The find command can be used to find files matching all sorts of different criteria

Use the command find / -name "*syslog*" to find all of the files and directories on your system with "syslog" somewhere in the name (This may take awhile).

Now try find / -name syslog

What were the results this time?____________________________________________________________

Use the command find / -path "*doc*bash*" to find files and directories whose full path includes the term "doc" followed by "bash" in some manner.
Finding setuid files

Run the command find / -perm -u+s to list files with the setuid bit set

Name 5 of the results:________________________________________________________________

The locate command

View the man page for the commands locate and updatedb
If your system doesn't have a locate database built you will need to run the command updatedb as root
Type the command locate syslog | nl

How many results were returned from this command?_____________________________________
Where is the syslogd configuration file on your system?____________________________________
(If you aren't sure from the output read the man page for syslogd).

Notice how much faster locate is than find, also note that locate uses a database for finding files so if the database is out of date it won't be much help for finding newly created files.
As a normal user run the command locate root | nl. How many results were returned?_________________
Now su to root and run the same command locate root | nl. How many results this time?_______________

The whereis command

What does whereis tell you (type whatis whereis)?_____________________________________________

Type the command whereis grub. What directory is grub in?_______________________
Type the command whereis lilo. What directory is lilo in?__________________________

Type the command whereis whereis. What directory is whereis in?___________________

The which command

What does which tell you (type whatis which)?_________________________________________________
Type the command which ls. What directory is ls in?____________________________

The type command

Type the command type ls. What is the output?________________________________________________
Type the command type cd. What is the output?________________________________________________
Type the command type vi. What is the output?________________________________________________

Permissions

Give the chmod command to change permissions on file1 to give:

Owner - read write execute
Group - read write
Other (or world) - read only
$___________________________________________________________________

Give the chmod command to change permissions on file2 to give:

Owner - read execute
Group - read execute
Other - no permissions
and set the setuid bit
$___________________________________________________________________

Give the chmod command to change permissions on file3 to give:

Owner - read write execute
Group - read execute
Other - execute
$___________________________________________________________________

Give the chmod command to add read permission for the group ownership of file4 but without modifying other existing permissions:_____________________________________________________________________________

With a user account can you change file permissions on /home?______________________
What is your standard file creation mode (type umask to see)?______________________
What umask would you use if you wanted all of the files you created to have by default

rwx for owner
rwx for group
read only for other
_______________________________________________________

What is chown used for?______________________________________________________________________

Shell Features and Customization (this doesn't go into everything but at least it's a start)

Change to /usr on your system

Use ls to see the directory listing
Next type echo *

Describe the output of echo * ?_____________________________________________________________

Next type echo "*"

What was the output of echo "*" ?__________________________________________________________

Set a variable called SOMEVAR, type SOMEVAR=/etc

Now try cd SOMEVAR and cd $SOMEVAR to see what one will take you to /etc

Which one took you to /etc?______________________________________________

What does echo SOMEVAR give you as output?__________________________________
What does echo $SOMEVAR give you as output?_________________________________
What does echo $SHLVL give you as output?_____________________________________
Now start a subshell by typing bash

Now what does echo $SHLVL give you as output?____________________________________

Now what does echo SOMEVAR give you as output?__________________________________

Now what does echo $SOMEVAR give you as output?_________________________________

Next exit your subshell by typing exit
Turn SOMEVAR to an environmental variable by typing export SOMEVAR
Once again start a subshell by typing bash

Now what does echo SOMEVAR give you as output?__________________________________

Now what does echo $SOMEVAR give you as output?_________________________________
Next exit your subshell by typing exit

You can see what your environment is by typing printenv (or env)

How many environmental variables are currently set, type printenv | nl ?___________________________________
Set a variable called SOMEVAR2, type SOMEVAR2=/bin
How many environmental variables are set now, type printenv | nl ?_______________________________________

You can unset these variabls by typing unset SOMEVAR SOMEVAR2

Now how many environmental variables are set, type printenv | nl ?_______________________________________

Bash has some built-in shell variables, here are a couple

What is the output of the following:

echo $SECONDS _________________________________________
echo $BASH _____________________________________________
echo $PWD ______________________________________________
echo $BASH_VERSION ___________________________________

There are some config files for bash that may exist in your home directory

Which of the following exist in your home directory, type ls -a ~

.bashrc ________

.profile ________

.bash_profile _______

.bash_history ________

.bash_logout ________

.bash_login ________

If both .profile and .bash_profile exist in your home directory only one gets run when you create a login shell.
If one or both of these files does not exist create them. Next edit your either your existing files or newly created files to add the lines echo "this is .bash_profile" and echo "this is .profile" respectively. Now you can create a login shell to see which gets ran by typing bash --login

If both of these files exist which one gets ran?________________________________________________

How would you redirect the output of the date command to a file named date.txt?________________________________
How would you append the output of the date command to a file named file1?___________________________________
(give the actual command for these).

Use the cut command on the output of a long directory listing in order to display only the file permissions. Then pipe this output to sort and uniq to filter out any double lines. Then use the wc to count the different permission types in this directory. The output should be a number on a single line only. Once you figure it out give exactly what you would type to do this in one line. __________________________________________________________________________________
(read the man pages for these commands, the answer will look something like: cmd -options | cmd -options | cmd | cmd ...)
(when I did this on my system I counted 2 extra lines, a blank line and a line with "total" in it, these were from the output of ls -l, don't worry about whether or not lines like this these are counted).

Create your own .bashrc file

Include at minimum the following personal customizations (make sure they all work)

A comment with YOUR NAME
Create at least 3 or 4 aliases

Set your umask to some value
Set PS1 (the variable that defines your prompt) to something

print out your file and turn it in with this lab

Write a Basic Script

Write a script called getinfo

This script will take one command line argument which will be the name of a program (additional arguments can be ignored).

This script will then run whatis, whereis and type -a providing the same argument that was passed to the script getinfo. Here is an example where I call getinfo on my computer three different times:

todd@sophia:~$ ./getinfo type
type [builtins]      (1)  - bash built-in commands, see bash(1)
type: /usr/share/man/man1/type.1.gz
type is a shell builtin

todd@sophia:~$ ./getinfo ls
ls                   (1)  - list directory contents
ls: /bin/ls /usr/share/man/man1/ls.1.gz
ls is /bin/ls

todd@sophia:~$ ./getinfo cd
cd [builtins]        (1)  - bash built-in commands, see bash(1)
cd                   (n)  - Change working directory
cd: /usr/share/man/man1/cd.1.gz /usr/share/man/mann/cd.n.gz
cd is a shell builtin

When getinfo is called with no arguments it will print the usage message as below:
```
todd@sophia:~$ ./getinfo 
Usage: getinfo COMMANDNAME
please try again...
```
(Notice that when getinfo was called without any arguments there was no additional error messages (for example, "usage: whatis keyword ..." or "whereis [ -sbmu ] [ -SBM dir ... -f ] name..."). Therefore this script will need to check that it was called with at least one command line argument.
I recommend writing this script using bash but you can use any of the following if you prefer sh, csh, tcsh, ksh. or perl.
To run the script you will need to have execute permission on it and have it in your PATH (or give the path like I did above ./getinfo).
Please include one line of documentation

# getinfo script - written by YOUR NAME

(You can document it more if it helps you but one line similar to above is all I care about).
Include a print out of this script with your turn-in