Fix singular spkg-configure

[mkoeppe]

Seen on archlinux-latest, https://github.com/FFY00/meson-python/actions/runs/3146686714/jobs/5115498470

Checking whether SageMath should install SPKG singular...
checking whether any of gmp ntl flint readline mpfr cddlib is installed as or will be installed as SPKG... no
checking for Singular... /usr/sbin/Singular
checking for SINGULAR... yes
checking that Singular's help is working... grep: warning: stray \ before white space
./configure: line 43759: test: too many arguments
no
configure: no suitable system package found for SPKG singular

CC: @dimpase @orlitzky

Component: build: configure

Author: Dima Pasechnik

Branch/Commit: 373bd38

Reviewer: Matthias Koeppe

Issue created by migration from https://trac.sagemath.org/ticket/34603

[dimpase]

comment:1

Does archlinux-latest use some sort of weird grep (3.8, the latest version from last month)? The error comes from

AS_IF([test x`printf "system(\"--browser\", \"builtin\"); \n help;" | Singular 2>&1 | grep "error\ occurred"` = x], [

i.e. grep does not understand "error\ occurred".

[dimpase]

comment:2

I've built grep 3.8, and indeed, I get a warning:

$ /tmp/bin/grep "bla\ baz" t # this is grep 3.8
/tmp/bin/grep: warning: stray \ before white space
bla baz
$ cat t
bla foo
bla baz
$ grep "bla\ baz" t # this is grep 3.6
bla baz

[dimpase]

comment:3

we can eiher just remove \ in the pattern, or send the warning to dev/null. Not sure what's the best, so I asked:

https://unix.stackexchange.com/questions/719384/the-correct-way-to-deal-with-spaces-in-a-pattern-for-grep

[dimpase]

comment:4

It seems we can just remove that \. I'll make a branch

[dimpase]

Commit: 373bd38

[dimpase]

Branch: u/dimpase/configure/nobackslash

[dimpase]

New commits:

373bd38

remove harmful \

[dimpase]

Author: Dima Pasechnik

[mkoeppe]

Reviewer: Matthias Koeppe

[vbraun]

Changed branch from u/dimpase/configure/nobackslash to 373bd38