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jcynix 4 hours ago

The [[…]] built-in test version was introduced in Peter Korn's korn shell, ksh88 IIRC. As where various other modernized notations like array variables, process substitution or

    $(command)
as a much more readable version of the backquotes version.

https://docs.oracle.com/cd/E36784_01/html/E36870/ksh88-1.htm...

While learning the Bourne shell as acstudent, I was rapidly lured by csh and then tcsh, but Tom Christiansen's pamphlet https://everything2.com/title/csh+programming+considered+har...

and (or?) the appearance of Paul Falstad's Z-Shell saved me ;-0