On Thu, Oct 25, 2012 at 9:43 PM, David Korn <[email protected]> wrote:
> cc: [email protected] > Subject: Re: [ast-users] [ksh93] Should ~$user be tilde expanded? > -------- > > > > I think bash behavior is correct according to > > > http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_ > > 06which > > says tilde expansion should be done before parameter expansion. > > > > Where do you see that? In section 2.6, it says > I see "The order of word expansion shall be as follows". I may misunderstand the context as English is not my first language. :) > "Tilde expansion (see Tilde Expansion), parameter expansion (see Parameter > Expansion), command substitution (see Command Substitution), and arithmetic > expansion (see Arithmetic Expansion) shall be performed, beginning to end. > See item 5 in Token Recognition. > > which implies that these should be simultaneously from beginning to end. > This make sense but ksh's behavior indicates that it makes two-pass parsing for ~$u, rather than one-pass from beginning to end. For a one-pass parsing, when it sees the ~ char and peeks at the next $ char it'll tell that tilde expansion is not possible; then it'll move forward and get the $ char and peeks at the next u char and it will know that parameter expansion is needed. > > David Korn > [email protected] >
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