From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Denk Date: Thu, 21 Jul 2011 15:11:30 +0200 Subject: [U-Boot] u-boot environment variable parsing In-Reply-To: References: Message-ID: <20110721131130.65D8F16AB841@gemini.denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Dear "Hebbar, Gururaja", In message 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 -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de A morsel of genuine history is a thing so rare as to be always valuable. - Thomas Jefferson