On Thu, 25 Oct 2012 22:03:35 +0800 Clark WANG wrote: > On Thu, Oct 25, 2012 at 9:43 PM, David Korn <[email protected]> wrote: > > > 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.
> I see "The order of word expansion shall be as follows". I may > misunderstand the context as English is not my first language. :) "The order" refers to the order of the numbered list 1 2 3 4 the key phrase for 1. is "beginning to end" which means "altogether" > > "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] > > > --14dae93408b9b53bc204cce2add7 > Content-Type: text/html; charset=UTF-8 > Content-Transfer-Encoding: quoted-printable > <font><font face=3D"arial,helvetica,sans-serif"></font></font>On Thu, Oct 2= > 5, 2012 at 9:43 PM, David Korn <span dir=3D"ltr"><<a href=3D"mailto:dgk@= > research.att.com" target=3D"_blank">[email protected]</a>></span> wro= > te:<br> > <div class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margi= > n:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">cc: <a href=3D"ma= > ilto:[email protected]">[email protected]</a><br> > Subject: Re: [ast-users] =C2=A0[ksh93] Should ~$user be tilde expanded?<br> > --------<br> > <div class=3D"im"><br> > <br> > > I think bash behavior is correct according to<br> > > <a href=3D"http://pubs.opengroup.org/onlinepubs/009695399/utilities/xc= > u_chap02.html#tag_02_" target=3D"_blank">http://pubs.opengroup.org/onlinepu= > bs/009695399/utilities/xcu_chap02.html#tag_02_</a><br> > > 06which<br> > > says tilde expansion should be done before parameter expansion.<br> > ><br> > <br> > </div>Where do you see that? =C2=A0In section 2.6, it says<br></blockquote>= > <div><br>I see "The order of word expansion shall be as follows".= > I may misunderstand the context as English is not my first language. :)<br= > > > <br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord= > er-left:1px #ccc solid;padding-left:1ex"> > <br> > "Tilde expansion (see Tilde Expansion), parameter expansion (see Param= > eter<br> > Expansion), command substitution (see Command Substitution), and arithmetic= > <br> > expansion (see Arithmetic Expansion) shall be performed, beginning to end.<= > br> > See item 5 in Token Recognition.<br> > <br> > which implies that these should be simultaneously from beginning to end.<br= > ></blockquote><div><br>This make sense but ksh's behavior indicates tha= > t it makes two-pass parsing for ~$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 k= > now that parameter expansion is needed.<br> > </div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-l= > eft:1px #ccc solid;padding-left:1ex"> > <span class=3D"HOEnZb"><font color=3D"#888888"><br> > David Korn<br> > <a href=3D"mailto:[email protected]";>[email protected]</a><br> > </font></span></blockquote></div><br> > --14dae93408b9b53bc204cce2add7-- > --===============3356089777672575947== > Content-Type: text/plain; charset="us-ascii" > MIME-Version: 1.0 > Content-Transfer-Encoding: 7bit > Content-Disposition: inline > _______________________________________________ > ast-users mailing list > [email protected] > https://mailman.research.att.com/mailman/listinfo/ast-users > --===============3356089777672575947==-- _______________________________________________ ast-users mailing list [email protected] https://mailman.research.att.com/mailman/listinfo/ast-users
