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.
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