[sr #110657] Autoconf configure script considers absence of usable grep a fatal error, although it only uses egrep thereafter

[Alain Knaff]

URL:
  <https://savannah.gnu.org/support/?110657>

                 Summary: Autoconf configure script considers absence of
usable grep a fatal error, although it only uses egrep thereafter
                 Project: Autoconf
            Submitted by: alainknaff
            Submitted on: Sun 15 May 2022 08:11:13 PM CEST
                Category: None
                Priority: 5 - Normal
                Severity: 3 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
        Operating System: None

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Details:

Configure scripts generated by autoconf first test for a "usable" grep (i.e.
one which understands the -e option, and supports multiple -e options), and
then after that looks for an egrep candidate.

By default it tries to use grep -E for egrep, or if that doesn't work, it
tries actual egrep.

During the rest of the script (most scripts in any case, not sure about some
exotic tests), $EGREP is only ever used, not $GREP.

This works fine on most platforms, where grep an egrep are the same binary
anyways, and change regular expression syntax depending on how they are
called.

Not so on AT&T UnixPC, where they are largely independent of each other. Grep
seems to be generally the older binary, and generally supports less command
line options than egrep.
For example, grep does not support -e , but egrep does.

This lack of support of -e makes the configure script fail, although there is
a usable egrep.

Fix: make lack of "usable" grep on non-fatal error (and only try to use egrep
directly in that case, rather than grep -E)






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