Linux in a Nutshell, Fifth Edition

678

|

Chapter 6: The Bash Shell and Korn Shell

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

return

return [n]

Use inside a function definition. Exit the function with status n or

with the exit status of the previously executed command.

select

select x [in list]

do

commands

done

Display a list of menu items on standard error, numbered in the

order they are specified in list.Ifnoin list is given, items are taken

from the command line (via "$@"). Following the menu is a

prompt string (set by PS3). At the PS3 prompt, users select a menu

item by typing its line number, or they redisplay the menu by

pressing the Enter key. User input is stored in the shell variable

REPLY. If a valid item number is typed, commands are executed.

Typing EOF terminates the loop.

Example

PS3="Select the item number: "

select event in Format Page View Exit

do

case "$event" in

Format) nroff $file | lp;;

Page) pr $file | lp;;

View) more $file;;

Exit) exit 0;;

* ) echo "Invalid selection";;

esac

done

The output of this script looks like this:

1. Format

2. Page

3. View

4. Exit

Select the item number:

set

set [options arg1 arg2 ...]

With no arguments, set prints the values of all variables known to

the current shell. Options can be enabled (-option) or disabled

(+option). Options can also be set when the shell is invoked. (See

the earlier section “Invoking the Shell.”) Arguments