Subject: Re: psh
To: Christos Zoulas <>
From: dustin sallings <>
List: current-users
Date: 10/19/1998 00:11:33
On Mon, 19 Oct 1998, Christos Zoulas wrote:

// What is wrong with:
// for i in `cat machinelist`
// do
// 	ssh -n $i "$@" &
// done

	There's no control over how many it'll run.  When I've got 1024
machines in machinelinst, it'd require something like 3072-4096 processes
to tell them all to take a new file.  With pfor, I tell it to do basically
that, but at most 8 at a time, which will save a *lot* of time, but not
blow the machine up in the meantime.

	Also, the syntax gets a bit funny when I have to do that whole
thing in a subshell.  Consider a more realistic loop (one that does more
than one thing):

pfor i in 3 5 11 21 8 9 13 7
        echo sleep $i
        sleep $i
        echo $i finished

	I could wrap the whole thing in parens or {}'s to get a subshell,
then background the whole subshell, but it looks a lot funnier than just
throwing a p in front of the for.

	BTW, I've replaced the MAXKIDS thing with a normal shell set since
I couldn't figure out how to read local vars cleanly inside of sh itself.
Now, to run 8 simultanous iterations of a loop, you just do this:

set -j8

	I used -j because it's the same flag as parallel make, and wasn't

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