On Tue, Aug 29, 2006 at 01:57:27PM +0100, Julian Gilbey wrote: > On Tue, Aug 29, 2006 at 01:40:38PM +0200, David Weinehall wrote: > > Quoting from "Shell & Utilities"/"2.6.4 Arithmetic Expansion" of SuSv3: > > > > "If the shell variable x contains a value that forms a valid integer > > constant, then the arithmetic expansions "$((x))" and "$(($x))" shall > > return the same value." > > > > I cannot seem to find any reasonable way to parse this other than that > > $((x+1)) should be treated in the same way that $(($x+1)) would be. > > Maybe, maybe not. But this is not the behaviour of dash. Maybe SuSv3 > differs from POSIX in this respect, or maybe this is a bug in dash?
I don't know, but in my experience posh adheres closer to the standards than dash does, and posh accepts the $((x+1)) notion. "The core of the Single UNIX Specification, Version 3 is also IEEE Std 1003.1. The latest 2004 edition incorporates IEEE Std 1003.1-2001 and two technical corrigendum. IEEE Std 1003.1-2001 is a major revision and incorporates IEEE Std 1003.1-1990 (POSIX.1) and its subsequent amendments, and IEEE Std 1003.2-1992 (POSIX.2) and its subsequent amendments, combined with the core volumes of the Single UNIX Specification, Version 2. It is technically identical to The Open Group, Base Specifications, Issue 6; they are one and the same documents, the front cover having both designations. The final draft achieved 98% approval by the IEEE ballot group and was officially approved by the IEEE-SA Standards Board on December 6th 2001." In other words, SuSv3 is POSIX.1 + POSIX.2 + errata. > Also, note that "x+1" is not a shell variable, so $((x+1)) may not be > treated in the same way as the special case $((x)). Well, while I guess that is a *possible* interpretation, it would be fairly inconsistent, something that the rest of SuSv3 tries to avoid, so it seems highly unlikely. However, dash does not support $((x)) either, so I'd say that dash is buggy in any case, since it can be argued that SuSv3 is the clarified version of POSIX. Regards: David -- /) David Weinehall <[EMAIL PROTECTED]> /) Rime on my window (\ // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ // Diamond-white roses of fire // \) http://www.acc.umu.se/~tao/ (/ Beautiful hoar-frost (/ -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
