Greg Wooledge wrote in <zk57gsgiubfkw...@wooledge.org>: |On Thu, May 23, 2024 at 06:56:01AM +0800, Dan Jacobson wrote: |> It seems these should both make one line "+ a=b c=b" output, |> |> for s in sh bash |> do $s -xc 'a=b c=$a'
Only to note that this is not portable. The FreeBSD shell will not assign "b" to "c" for this one! |> done |> |> I mean they give the same results, but bash splits it into |> two lines, so the user reading the bash -x output cannot tell |> if one (correct) or two (incorrect) lines were used. |> They can tell with sh -x. | |Does it actually matter? What makes bash's output "incorrect", exactly? | |> By the way, I looked up and down the man page, |> and wasn't sure if it says one should expect |> $c to end up as c= or c=b in fact! | |I don't know where it's documented, but assignments and expansions are |always performed left to right. In your example, a value is assigned |to variable a before $a is expanded. | |> And I'm not sure the man page says to expect two lines or one of -x |> output either, when using sh vs. bash. | |I don't see why it matters. The purpose of the -x output is to show |you what the shell is doing, so that you can debug your script. As |long as the output is *clear*, it's doing its job. | |In bash's case, | |hobbit:~$ bash -xc 'a=b c=$a' |+ a=b |+ c=b | |you can very easily see the order in which the assignments happen, and |the values that are assigned. --End of <zk57gsgiubfkw...@wooledge.org> --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
