Re: [PATCH] common/rc: fix MKSWAP_PROG quoting

[Zorro Lang <zlang@redhat.com>]

On Tue, Aug 31, 2021 at 11:04:26AM +0800, Murphy Zhou wrote:
> After commit
>   0e4dd8b9 common/rc: fix ignoring of errors on
> we are getting this error message when running swapfiles tests:
>   +./common/rc: line 2553: MKSWAP_PROG: command not found
> 
> Signed-off-by: Murphy Zhou <xzhou@redhat.com>
> ---
>  common/rc | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/common/rc b/common/rc
> index 46b6b220..0597de13 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -2550,7 +2550,7 @@ _format_swapfile() {
>  	$CHATTR_PROG +C "$fname" > /dev/null 2>&1
>  	_pwrite_byte 0x61 0 "$sz" "$fname" >> $seqres.full
>  	# Ignore permission complaints on filesystems that don't support perms
> -	$(MKSWAP_PROG "$fname" 2> >(grep -v 'insecure permission' >&2)) >> $seqres.full
> +	($MKSWAP_PROG "$fname" 2> >(grep -v 'insecure permission' >&2)) >> $seqres.full

The change history is:

Commit 0c95c8ac tried to "hide permision warning", so did:
-       $MKSWAP_PROG "$fname" >> $seqres.full
+       # Ignore permission complaints on filesystems that don't support perms
+       $MKSWAP_PROG "$fname" 2> >(grep -v 'insecure permission' >&2) >> $seqres.full

Then commit 0e4dd8b9 said "it broke older versions of bash such as 4.4.23", so tried
to use "a $(foo) to run the executable":
-       $MKSWAP_PROG "$fname" 2> >(grep -v 'insecure permission' >&2) >> $seqres.full
+       $(MKSWAP_PROG "$fname" 2> >(grep -v 'insecure permission' >&2)) >> $seqres.full

Now this patch try to do ($FOO_PROG):
($MKSWAP_PROG "$fname" .....)

I'm *not* a bash expert, if I'm wrong feel free to correct me:) If the original problem
is trying to hide permision warning from stderr, and to avoid new syntax breaking old
bash, Why we must struggle with this complex syntax which isn't compatible. How about:

$MKSWAP_PROG "$fname" >> $seqres.full 2>&1 | grep -v "insecure permission"

Or other better and compatible way ?

Thanks,
Zorro

>  }
>  
>  _swapon_file() {
> -- 
> 2.20.1
>