ksh93 - test, test and then test a bit more

Since ksh93 is now [1] available for most version of UNIX (and Linux), we have been tentatively moving our courses (especially scripting) towards the new syntax. At the moment the scripting course is still based predominantly on the pre-93 versions, but we now introduce a fair amount of comparisons, 'gotchas' and demos of new capabilities and syntax.

Truth is, months later we still find new idiosyncrasies.

Here is one I found today, whilst teaching... Imagine the following example, to illustrate the need for double quotes when creating and accessing variables:

If you want to assign a value that has leading or trailing spaces or tabs, you need the quotes:

$ address=" 6 Pie Corner"

Would you expect to see the leading spaces if you didn't use the quotes when accessing the variable? Of course not! Well, in ksh93 it works! Haven't checked yet if this behaviour is driven by any particular setting or switch, but in my CentOS 5 ksh (Version M 1993-12-28 r), the following worked out of the box:

$ print -- $address

<space><space>6 Pie Corner


[1] in the original posting this said 'not' - corrected 18/10/2007