Programming with the UNIX system shell

Shell programming exercises

2-1.

Create a shell program called time from the following command line:

banner `date | cut -c12-19`

2-2.

Write a shell program that gives only the date in a banner display. Be careful not to give your program the same name as a UNIX system command.

2-3.

Write a shell program that sends a note to several people on your system.

2-4.

Redirect the date command without the time into a file.

2-5.

Echo the phrase ``Dear colleague'' in the same file as the previous exercise, without erasing the date.

2-6.

Using the above exercises, write a shell program that sends a memo to the same people on your system mentioned in Exercise 2-3. Include in your memo:

lines at the top that include the current date and the words ``Dear colleague''
the body of the memo (stored in an existing file)
a closing statement

2-7.

How can you read variables into the mv.file program?

2-8.

Use a for loop to move a list of files in the current directory to another directory. How can you move all your files to another directory?

2-9.

How can you change the program search, so that it searches through several files?

Hint:

for file
in $*

2-10.

Set the stty options for your environment.

2-11.

Change your prompt to the word Hello.

2-12.

Check the settings of the variables $HOME, $TERM, and $PATH in your environment.

Answers

2-1.

$ cat time
banner `date | cut -c12-19`
$
$ chmod u+x time

2-2.

   $ cat mydate
   banner `date | cut -c1-10`
   $

2-3.

   $ cat tofriends
   echo Type in the name of the file containing the note.
   read note
   mail janice marylou bryan < $note
   $

Or, if you used parameters for the logins (instead of the logins themselves) your program may have looked like this:

   $ cat tofriends
   echo Type in the name of the file containing the note.
   read note
   mail $* < $note
   $

2-4.

date | cut -c1-10 > file1

2-5.

echo Dear colleague >> file1

2-6.

$ cat send.memo
date | cut -c1-10 > memo1
echo Dear colleague >> memo1
cat memo >> memo1
echo A memo from M. L. Kelly >> memo1
mail janice marylou bryan < memo1
$

2-7.

$ cat mv.file
echo type in the directory path
read path
echo type in filenames, end with CTRL-d
while
read file
do
mv $file $path/$file
done
echo all done
$

2-8.

$ cat mv.file
echo Please type in directory path
read path
for file in $*
do
mv $file $path/$file
done
$

The command line for moving all files in the current directory is:

   $ mv.file *

2-9.

See the hint provided with exercise 2-9.

$ cat search
for file
in $*
do
if grep $word $file >/dev/null
then echo $word is in $file
else echo $word is NOT in $file
fi
done
$

2-10.

Add the following lines to your .profile:

   stty -tabs
   stty erase
   stty echoe

2-11.

Add the following command lines to your .profile:

   PS1=Hello
   export PS1

2-12.

Enter the following commands to check the values of the HOME, TERM, and PATH variables in your home environment:

$ echo $HOME
$ echo $TERM
$ echo $PATH