IT 244: Introduction to Linux/Unix

IT 244: Introduction to Linux/Unix
Homework 11

Due

Sunday, April 21st at 11:59 PM

What You Need to Do

Create the following scripts
- parameters.sh
- log_users.sh
- envir.sh
These scripts must be in an hw11 directory under your hw directory

Setup

From your home directory go to your it244 directory
```
cd it244
```
Go to your hw directory
```
cd hw
```
Create an hw11 directory
```
mkdir hw11
```
Enter this new directory
```
cd hw11
```

Special Instructions

Each of these scripts must have a hashbang line
Each of these script must be made executable using chmod
```
chmod 755 *.sh
```
Each script must have a comment that describes what the script does
If the script needs command line arguments the script must check that the right number are provided
If the script does not get the right number of command line arguments it should print an error message and quit.

Specification

parameters.sh

The script should
1. Print the the positional parameters 0 through 4 to the terminal.
2. Print the number of arguments given to this script from the command line.
Each positional parameter must be labeled and printed on a separate line
You do not need a for loop for this script
A series of echo commands will do
Be sure to test this script several times to make sure it works
Your output should look something like this

$ ./parameters.sh foo bar bletch bling
$0 ./parameters.sh
$1 foo
$2 bar
$3 bletch
$4 bling
$# 4

log_users.sh

The script should
1. Define a variable log whose value is the filename for the log file, users.log
2. Append the date to the log file whose name is contained in log
3. Append a line of dashes to this log file to act as a separator
4. Append a list of the users currently on to pe15 to this log file
5. Append a blank line to the log file.
The value users.log should be assigned to the variable at the top of the script
Thereafter, never never write "users.log" in your script
Use the value of log instead
Be sure you append the output so the log grows each time you run the script
Run cat on users.log to see the results of running this script
After running this script, the log file users.log should look something like this

Wed Dec  5 10:38:58 EST 2012
-----------------
Login    Name                      Tty      Idle  Login Time   Office     Office Phone
it244gh  Dummy for Glenn Hoffman   pts/0          Dec  5 10:29 (dsl092-066-161.bos1.dsl.speakeasy.net)

envir.sh

The script should
1. Test that it has been given a command line argument.
  It should print a usage message and exit if no argument is given.
2. List all global variables that contain the string given in the command line argument.
Use an if ... then ... else to check for a command line argument
Use env piped into grep along with a positional parameter
If I wanted to see all variables that contained "SH", I would run

./envir.sh SH
$ ./envir.sh SH
SHELL=/bin/bash
SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.TQqfDTv8LD/Listeners
SHLVL=2