if u var=value command ; the var's only for cmd and disappears afterwards if u var=val ; cmd ; its not for cmd , excepts exported and is set after cmd , usual behav
old rule On Thu, May 23, 2024, 3:34 PM Robert Elz <k...@munnari.oz.au> wrote: > Date: Thu, 23 May 2024 09:04:48 -0400 > From: Chet Ramey <chet.ra...@case.edu> > Message-ID: <d7b7717e-794f-4447-a2df-894caf0f0...@case.edu> > > > | The bash output clearly tells you the > | order of operations, which is the whole purpose of -x. > > But it can be horribly misleading. Consider what bash does with > this similar case (I used 5.3a1 but I suspect any version would do) > > bash-5.3a1 -xc 'a=a b=b; a=1 b=2 cat /dev/null; echo $a' > + a=a > + b=b > + a=1 > + b=2 > + cat /dev/null > + echo a > a > > versus > > bash-5.3a1 -xc 'a=a b=b; a=1 b=2; cat /dev/null; echo $a' > + a=a > + b=b > + a=1 > + b=2 > + cat /dev/null > + echo 1 > 1 > > The only difference in the two outputs from -x is the arg to the echo > command at the end, no indication at all why they're different. > > > On the other hand: > > sh -xc 'a=a b=b; a=1 b=2 cat /dev/null; echo $a' > + a=a b=b > + a=1 b=2 cat /dev/null > + echo a > a > > sh -xc 'a=a b=b; a=1 b=2 ; cat /dev/null; echo $a' > + a=a b=b > + a=1 b=2 > + cat /dev/null > + echo 1 > 1 > > and it is quite clear what is happening. > > Personally I'd think it more likely that your average reader would > interpret "a=1 b=2" as being executed left to right than that they'd > somehow guess that "a=1" isn't really happening in shell environment. > > kre > > >
