GNU bug report logs - #54484
"sed -E" is not specified by POSIX

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Keith Thompson <Keith.S.Thompson <at> gmail.com>
To: bug-sed <at> gnu.org
Cc: Keith Thompson <Keith.S.Thompson <at> gmail.com>
Subject: "sed -E" is not specified by POSIX
Date: Sun, 20 Mar 2022 14:36:05 -0700

$ sed --version
sed (GNU sed) 4.8
...

GNU sed's "man" and "info" documentation both say that the "-E"
option is specified by POSIX.  The man page says:

    The -E option switches to using extended regular expressions
    instead; it has been supported for years by GNU sed, and is now
    included in POSIX.

The info documentation says:

    '-E'
    '-r'
    '--regexp-extended'
         Use extended regular expressions rather than basic regular
         expressions.  Extended regexps are those that 'egrep' accepts; they
         can be clearer because they usually have fewer backslashes.
         Historically this was a GNU extension, but the '-E' extension has
         since been added to the POSIX standard
         (http://austingroupbugs.net/view.php?id=528), so use '-E' for
         portability.  GNU sed has accepted '-E' as an undocumented option
         for years, and *BSD seds have accepted '-E' for years as well, but
         scripts that use '-E' might not port to other older systems.  *Note
         Extended regular expressions: ERE syntax.

The linked web page on austingroupbugs.net (which, BTW, should
probably specify "https" rather than "http") is an enhancement request,
originally submitted in 2011.  It has "Resolution: Accepted As Marked"
and "Status: Applied", which certainly seems to imply that it's been
incorporated into POSIX, but The Open Group Base Specifications Issue 7,
2018 edition at
    https://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
doesn't mention the "-E" option.

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Keith Thompson <Keith.S.Thompson <at> gmail.com>
To: bug-sed <at> gnu.org
Cc: Keith Thompson <Keith.S.Thompson <at> gmail.com>
Subject: Re: bug#54484: "sed -E" is not specified by POSIX
Date: Mon, 21 Mar 2022 13:37:47 -0700

Quoting a discussion in comp.unix.shell:

Keith Thompson:
> The enhancement request was submitted in 2011.  The resolution is
> "Accepted As Marked" and the status is "Applied", so I'm not entirely
> sure what's going on.  But in any case, The Open Group Base
> Specifications Issue 7, 2018 edition doesn't mention "-E".

Geoff Clare:
> "Applied" means the edits have been made in the (troff) source of SUS.
> In this specific case the edit was applied long enough ago that it
> was included in the latest draft (2.1) of the next revision (Issue 8)
> that was made available to reviewers in August 2021.

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