Linux in a Nutshell, Fifth Edition

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Bash and Korn

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

-n count

Read at most count bytes. Not ksh88.

-p prompt

Bash: print prompt before reading input.

-p Korn shell: read from the output of a |& coprocess.

-r Raw mode; ignore \ as a line-continuation character.

-s Bash: read silently; characters are not echoed.

-s Korn shell: save input as a command in the history file.

-t timeout

When reading from a terminal or pipe, if no data is entered

after timeout seconds, return 1. This prevents an application

from hanging forever, waiting for user input. Not ksh88.

-u[n]

Read input from file descriptor n (default is 0).

Examples

Read three variables:

$ read first last address

Sarah Caldwell 123 Main Street

$ echo "$last, $first\n$address"

Caldwell, Sarah

123 Main Street

Prompt yourself to enter two temperatures, Korn shell version:

$ read n1?"High low: " n2

High low: 65 33

readonly

readonly [-afp] [variable[=value] ...]

Prevent the specified shell variables from being assigned new

values. An initial value may be supplied using the assignment

syntax, but that value may not be changed subsequently.

Options

ksh88 does not accept options for this command.

-a Each variable must refer to an array. Bash only.

-f Each variable must refer to an function. Bash only.

-p Print readonly before printing the names and values of read-

only variables.