what's the use of "{ list }" in /bin/sh?

[Timothy Reed]

In article <6954 at sigi.Colorado.EDU> wu at spot.Colorado.EDU (WU SHI-KUEI) writes:
>In article <23590 at teknowledge-vaxc.ARPA> mkhaw at teknowledge-vaxc.ARPA (Mike Khaw) writes:
>>
>>Under what circumstances is this useful (i.e., why whould one want to
>>put braces around a list of commands)?
>
>[ -r "$filename" ] || { echo "Cannot open $filename for reading" ; exit 1 }
>is another way of writing

Is "[ -r "$filename" ] || { echo "error" ; exit 1 }" faster than
"if [ -r filename ] ; then echo "error" ; exit ; fi" ???

Thanks!
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