Write a script called greetme that will:

Make sure your script is executable.

								chmod +x greetme
							

What was the first line of your script? Why do you need this line?

Write a script called rename that will take two arguments: the first argument is the name of the original file and the second argument is the new name for the file.

If the user does not provide two arguments, a usage message will appear on the screen and the script will exit. Here is an example of how the script works:

$ rename
								Usage: rename oldfilename newfilename
$
$ rename file1 file2
								file1 has been renamed file2
								Here is a listing of the directory:
								a file2
								b file.bak
							

The following find command (SunOS) will list all files in the root partition that are larger than 100K and that have been modified in the last week. (Check your man pages for the correct find syntax on this system.)

								find / –xdev –mtime –7 –size +200 –print
							

Write a script called bigfiles that will take two arguments: one will be the mtime and one the size value. An appropriate error message will be sent to stderr if the user does not provide two arguments.

If you have time, write a script called vib that creates backup files for vi. The backup files will have the extension bak appended to the original name.

Write a script called nosy that will:

Create a text file called datafile (unless this file has already been provided for you). Each entry consists of fields separated by colons. The fields are:

Create a script called lookup that will:

Try the -x and -v options for debugging your script. How did you use these commands? How do they differ?

Write a script called checking that will:

In the lookup script, ask the user if he or she would like to add an entry to the datafile. If the answer is yes or y:

Rewrite checking. After checking whether the named user is in the /etc/passwd file, the program will check to see if the user is logged on. If so, the program will print all the processes that are running; otherwise it will tell the user:

								"<user is not logged on."
							

Use the let command to evaluate a set of grades. The script will ask the user for his or her numeric grade on an examination. ( Use declare -i ). The script will test that the grade is within a legal range between 0 and 100. If not, the program will exit. If the grade is within the legal range, the user's letter grade will be displayed, e.g., You received an A. Excellent! The range is:

A (90-100) B (80-89) C (70-79) D (60-69) F (Below 60)

The lookup script depends on the datafile in order to run. In the lookup script, check to see if the datafile exists and if it is readable and writeable. Add a menu to the lookup script to resemble the following:

[1] Add entry.
[2] Delete entry.
[3] View entry.
[4] Exit.

You already have the Add entry part of the script written. The Add entryy routine should now include code that will check to see if the name is already in the datafile and if it is, tell the user so. If the name is not there, add the new entry.

Now write the code for the Delete entry, View entry, and Exit functions.

The Delete part of the script should first check to see if the entry exists before trying to remove it. If it does, notify the user; otherwise, remove the entry and tell the user you removed it. On exit, make sure that you use a digit to represent the appropriate exit status.

How do you check the exit status from the command line?

The ps command is different on BSD (Berkeley UNIX) and System 5 (ATT UNIX). Linux uses the BSD options to ps. On System 5, the command to list all processes is:

								ps –ef
							

On Linux, the command is:

								ps aux
							

Write a program called systype that will check for a number of different system types. The cases to test for will be:

AIX
LINUX
HP–UX
SCO
OSF1
ULTRIX
SunOS (Solaris / SunOs)
OS

Solaris, HP–UX, SCO, and IRIX are ATT-type systems. The rest are BSDish.

The version of UNIX you are using will be printed to stdout. The system name can be found with the uname -s command or from the /etc/motd file.

Write a script called timegreet that will:

Provide a comment section at the top of the script, with your name, the date, and the purpose of the program.

Convert the following program to use the case command rather than if/elif.

#!/bin/bash
# Comment section
you=$LOGNAME
   hour=$( date +%H )
echo "The time is: $( date +%T )"
 if (( hour > 0 && hour < 12 ))
then
   echo "Good morning, $you!"
elif (( hour == 12 ))
then
   echo "Lunch time!"
elif (( hour > 12 && hour < 16 ))
then 
   echo "Good afternoon, $you!"
else
   echo "Good night, $you. Sweet dreams."
fi

Write a program called mchecker to check for new mail and write a message to the screen if new mail has arrived.

The size of a file can be found by looking at the output from ls -l, wc -c or from the find command.

Write a script that will:

Write a program called dusage that will mail a list of users, one at a time, a listing of the number of blocks they are currently using. The list of users will be in a file called potential_hogs. One of the users listed in the potential_hogs file will be admin.

Rewrite the last program, systype, as a function that returns the name of the system. Use this function to determine what options you will use with the ps command in the checking program.

The ps command to list all processes on ATT UNIX is:

								ps –ef

							

On Linux/BSD UNIX, the command is:

								ps –aux  or ps aux[9]
							

^[9] Using the leading dash with Linux will produce a warning. See the man page.

Write a function called cleanup that will remove all temporary files and exit the script. If the interrupt or hangup signal is sent while the program is running, the trap command will call the cleanup function.

Use a here document to add a new menu item to the lookup script to resemble the following:

[1] Add entry
[2] Delete entry
[3] Change entry
[4] View entry
[5] Exit

Write a function to handle each of the items in the menu. After the user has selected a valid entry, and the function has completed, ask if the user would like to see the menu again. If an invalid entry is entered, the program should print:

								"Invalid entry, try again."

							

and the menu will be redisplayed.

Create a submenu under View entry in the lookup script. The user will be asked if he or she would like to view specific information for a selected individual:

Use the trap command in a script to perform a cleanup operation if the interrupt signal is sent while the program is running.