Parsing "for" clause
in [Shell]
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From: Roman Cheplyaka on 13 Mar 2010 02:25 According to formal shell grammar http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html the "for" clause is defined by following productions: for_clause : For name linebreak do_group | For name linebreak in sequential_sep do_group | For name linebreak in wordlist sequential_sep do_group As can be seen from them, if there is no "in" reserved word, there can be no sequential_sep before do_group. However, all available to me shells (ksh, bash, dash, posh) accept both forms: for i do echo $i; done for i; do echo $i; done Are they all wrong or I missed something?
From: Stephane CHAZELAS on 13 Mar 2010 04:46 2010-03-12, 23:25(-08), Roman Cheplyaka: > According to formal shell grammar http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html > the "for" clause is defined by following productions: > > for_clause : For name linebreak > do_group > | For name linebreak in sequential_sep > do_group > | For name linebreak in wordlist sequential_sep > do_group > > As can be seen from them, if there is no "in" reserved word, there can > be no sequential_sep before do_group. > However, all available to me shells (ksh, bash, dash, posh) accept > both forms: > for i do echo $i; done > for i; do echo $i; done > > Are they all wrong or I missed something? FWIW, the Bourne shell (a non-POSIX shell, but POSIX shells descend from it) doesn't support the latter. Note that it's a a bug in posh if it supports it, it should be reported. But not in the other shells. POSIX doesn't prevent shell implementations from supporting it, but script writers from using it. posh was created as a tool to help script authors to write compliant scripts, so it should report an error on non-conformant syntax. -- Stéphane
From: Roman Cheplyaka on 13 Mar 2010 08:30
On Mar 13, 11:46 am, Stephane CHAZELAS <stephane_chaze...(a)yahoo.fr> wrote: > 2010-03-12, 23:25(-08), Roman Cheplyaka: > > > > > According to formal shell grammarhttp://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html > > the "for" clause is defined by following productions: > > > for_clause : For name linebreak > > do_group > > | For name linebreak in sequential_sep > > do_group > > | For name linebreak in wordlist sequential_sep > > do_group > > > As can be seen from them, if there is no "in" reserved word, there can > > be no sequential_sep before do_group. > > However, all available to me shells (ksh, bash, dash, posh) accept > > both forms: > > for i do echo $i; done > > for i; do echo $i; done > > > Are they all wrong or I missed something? > > FWIW, the Bourne shell (a non-POSIX shell, but POSIX shells > descend from it) doesn't support the latter. > > Note that it's a a bug in posh if it supports it, it should be > reported. But not in the other shells. POSIX doesn't prevent > shell implementations from supporting it, but script writers > from using it. > > posh was created as a tool to help script authors to write > compliant scripts, so it should report an error on > non-conformant syntax. Didn't know that. From debian package description: "posh is a stripped- down version of pdksh that aims for compliance with Debian's policy, and few extra features." And I didn't find any homepage besides Debian git repository. The original question (and similar questions earlier in this newsgroup) comes from my attempt to write such a tool, loker (http:// github.com/feuerbach/loker). I take standards compliance for serious, that's why I need to know which behaviour is correct one. |