Linux in a Nutshell, Fifth Edition

case | 655

Bash and Korn

This is the Title of the Book, eMatter Edition

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

added built-in version is used only if a path search would other-

wise have found a command of the same name. (This allows

replacement of system commands with faster, built-in versions.)

Otherwise, the built-in command is always found.

Options

-d Delete the built-in command name.

-f Load new built-in command from library.

-s Only print “special” built-ins (those designated as special by

POSIX).

case

case value in

pattern1) cmds1;;

pattern2) cmds2;;

.

.

.

esac

Execute the first set of commands (cmds1)ifvalue matches

pattern1, execute the second set of commands (cmds2)ifvalue

matches pattern2, etc. Be sure the last command in each set ends

with ;;. value is typically a positional parameter or other shell vari-

able. cmds are typically Unix commands, shell programming

commands, or variable assignments. Patterns can use file-

generation metacharacters. Multiple patterns (separated by |) can

be specified on the same line; in this case, the associated cmds are

executed whenever value matches any of these patterns. See the

Examples here and under eval.

The shells allow pattern to be preceded by an optional open paren-

thesis, as in (pattern). In Bash and ksh88, it’s necessary for

balancing parentheses inside a $( ) construct.

The Korn shell allows a case to end with ;& instead