April 2011
Intermediate to advanced
840 pages
18h 7m
English
Chapter 13
Handling User Input
In This Chapter
- Command line parameters
- Special parameter variables
- Being shifty
- Working with options
- Standardizing options
- Getting user input
So far you've seen how to write scripts that interact with data, variables, and files on the Linux system. Sometimes, you need to write a script that has to interact with the person running the script. The bash shell provides a few different methods for retrieving data from people, including command line parameters (data values added after the command), command line options (single-letter values that modify the behavior of the command), and the capability to read input directly from the keyboard. This chapter discusses how to incorporate these different methods into your bash shell scripts to obtain data from the person running your script.
Command Line Parameters
The most basic method of passing data to your shell script is to use command line parameters. Command line parameters allow you to add data values to the command line when you execute the script:
$ ./addem 10 30
This example passes two command line parameters (10 and 30) to the script addem. The script handles the command line parameters using special variables. The following sections describe how to use command line parameters in your bash shell scripts.
Reading Parameters
The bash shell assigns special variables, called positional parameters, to all of the parameters entered in a command line. This even includes the name of the program the ...
