On 02/14/2014 11:29 AM, Dan Kegel wrote: > The script > > eval export dir=~$LOGNAME > echo $dir This has been discussed by the POSIX folks. See: http://austingroupbugs.net/view.php?id=351 The standard added the definition of a 'declaration utility', which can evaluate its arguments in assignment context, and marked that 'export' is one such utility: >> At line 74276 (XCU export DESCRIPTION), add: >> The export special built-in shall be a declaration utility. Therefore, >> if export is recognized as the command word of a simple command, then >> subsequent words of the form name=word shall be expanded in an >> assignment context. See Section 2.9.1. Meanwhile, 'eval' is not allowed to be a declaration utility. Thus, once this POSIX interpretation is made live in Issue 8 (currently still unreleased), a conforming shell would have to evaluate this as: eval export dir=~$LOGNAME # not in assignment context eval 'export' 'dir=~buildbot' # actual arguments passed to eval export dir=~buildbot # declaration context, do tilde expansion dir gets /home/buildbot ksh and bash are compliant, dash needs to be patched. However, as Issue 8 POSIX is not yet released, dash is not yet non-compliant, and you are correct that workarounds exist while waiting for someone to write the patch for dash. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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