ado@elsie.UUCP (Arthur David Olson) (09/03/85)
The latest version of the news software "cunbatch" Bourne shell script I've received has this as its last line (after installation): exec /usr/lib/news/compress -d | /usr/local/rnews Now my guess was that the "exec" thrown in there was designed to get rid of a sub-shell that might wait around for "compress" to complete (after which it would report back to the parent shell that was interpreting the script). However, my rummaging on our 4.1bsd VAX system revealed that whether you had a script with a last line of exec sleep 30 | sleep 30 or a script with a last line of sleep 30 | sleep 30 (or, for that matter, a script with sleep 30 | exec sleep 30 or exec sleep 30 | exec sleep 30 as the last line) you ended up with two "sleep"s and one "sh". And so the question to folks on the net: on what system does the "exec" in the "cunbatch" do something useful--and what useful does it do? (Side question: is there any system on which it does harm?) (To forestall one bogus answer: it's true that the C shell treats sleep 30 | sleep 30 and exec sleep 30 | sleep 30 differently. My question is whether there's any system on which "sh" treats them differently.) -- UNIX is an AT&T Bell Laboratories trademark. Sleep is a Rip Van Winkle trademark. -- UUCP: ..decvax!seismo!elsie!ado ARPA: elsie!ado@seismo.ARPA DEC, VAX and Elsie are Digital Equipment and Borden trademarks