April 2011
Intermediate to advanced
840 pages
18h 7m
English
Chapter 10
Basic Script Building
In This Chapter
- Basic script building
- Using multiple commands
- Creating a script file
Now that we've covered the basics of the Linux system and the command line, it's time to start coding. This chapter discusses the basics of writing shell scripts. You'll need to know these basic concepts before you can start writing your own shell script masterpieces.
Using Multiple Commands
So far you've seen how to use the command line interface (CLI) prompt of the shell to enter commands and view the command results. The key to shell scripts is the ability to enter multiple commands and process the results from each command, even possibly passing the results of one command to another. The shell allows you to chain commands together into a single step.
If you want to run two commands together, you can enter them on the same prompt line, separated with a semicolon:
$ date ; who
Mon Feb 21 15:36:09 EST 2011
Christine tty2 2011-02-21 15:26
Samantha tty3 2011-02-21 15:26
Timothy tty1 2011-02-21 15:26
user tty7 2011-02-19 14:03 (:0)
user pts/0 2011-02-21 15:21 (:0.0)
$
Congratulations, you just wrote a shell script! This simple script uses just two bash shell commands. The date command runs first, displaying the current date and time, followed by the output of the who command, showing who is currently logged on to the system. Using this technique, you can string together as many commands as you wish, up to the ...
