UNIX Command Practice

Writing a Shell Script A shell script is just a file with a sequence of UNIX commands in it. Use a .sh extension for these to get proper syntax coloring. Here is an example. The echo command just spits what is handed it to stdout. Create this file.

#!/bin/bash
echo Hello, World!

Now make the file executable and it will run your UNIX command. Do that as follows.

$ chmod +x hello.sh
$ ./hello.sh
Hello, World!
$

The first line is called the shebang line. It basically says, "this is a shell script." After it, just insert the UNIX commmands you want to have run. You can put shell scripts in your ~/bin directory and run them from anywhere in the file system.

Here is another example. It gives you date, time and a calender. It shows the environment variables LOGNAME and HOSTNAME being accessed.

#!/bin/bash
echo Hello, $LOGNAME!
echo You are logged into the host $HOSTNAME
echo The current date and time are 
date
echo Here is a calendar for this month
cal
$ ./time.sh
Hello, morrison!
You are logged into the host fluorine.ncssm.edu
The current date and time are
Fri Feb 24 10:47:16 EST 2017
Here is a calendar for this month
    February 2017   
Su Mo Tu We Th Fr Sa
          1  2  3  4
 5  6  7  8  9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28

You are going to write a shell script that performs various manipulations with the file scrabble.txt which you can download in the navigation area.

There is also a skeleton file provided, practice.sh. All of the problems are present in the skeleton file.