One of the most basic and useful program tools in the shell itself. Its also a powerful programming environment

Step 1. Type the following command to create a new file:
CODE:
cat > new_script


Step 2. Type the following lines:
CODE:
echo Your files are
ls
echo today is
date
Press ENTER to move the cursor to a new line and press CTRL-D. At this point, the file new_script contains a series of shell commands.

Step 3. Examine the file to be certain it is correct:
CODE:
cat new_script
If there are errors, remove the file new_script and return to step 1 to create it again.

Step 4. Try to run the script by entering its name:
CODE:
new_script
It doesn't run because its not executable.

Step 5. Display the permission of the file by entering:
CODE:
ls -la new_script
Notice that the file is not executable. You must make it executable.

Step 6. Type the following command to make new_script executable:
CODE:
chmod +x new_script


Step 7. To see the new permission, enter:
CODE:
ls -l
You now have execute permission, as well as read and write permissions for the file.

Step 8. Execute the new script by typing its name:
CODE:
new_script
All the commands that you typed into the file are executed, and their output is sent to the screen.

Step 9. If you receive an error message such as:
CODE:
Command not found
Type the following:
CODE:
./new_script
This command line tells the shell exactly where to find the shell script, new_script, in your current directory knows as "dot."