Re: [U-Boot] u-boot environment variable parsing

Dear "Hebbar, Gururaja",

In message C82BA3053CFD354AACBD25EFBD2A4EC603F0193C2D@dbde02.ent.ti.com you wrote:

The question here is mmc_args re-uses variable bootargs as $(bootargs) & nand_args re-uses it as ${bootargs}. Note the difference in curly & flower brackets. "run mmc_args" fails for me however nand_args runs properly.

Does this not answer your question sufficiently?

My question is

1. Which is correct?

${...} is correct.

2. What is the difference between the two?

${...} is correct, and $(...) is not correct.

I have seen few boards using both methods.

$(...) was used in very old versions of U-Boot, but this got changed for the sake of compatibility with standard shell syntax.

Note that the simple cmmand line parser still accepts the obsolete $(...) format; the hush shell doesn't.

Best regards,

Wolfgang Denk