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BOOK: Beginning Linux Programming, 4th Edition ISBN 978-0-470-14762-7
This is the forum to discuss the Wrox book Beginning Linux Programming, 4th Edition by Neil Matthew, Richard Stones; ISBN: 9780470147627
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Old September 15th, 2009, 04:28 AM
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Default What is the meaning of ":=" in shell script ?

Hello,

Stones & Matthew's book Beginning Linux Programming 4/e, chapter 2, "Shell Programming", p50, there is a short explanation about : (null command).

I understand that the null command does nothing and it is also used as true.
But I do not understand the following : construct.

: ${ var:=value }

Perhaps the first ':' means doing nothing, but what is the second ':' followed by '=' ? , and what is ${ } ?

Thanks.
 
Old September 15th, 2009, 10:11 PM
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I have found the answer by myself.
The meaning of ":=" is explained at p72.




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