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Full Discussion: Understanding <<EOF
Top Forums Shell Programming and Scripting Understanding <<EOF Post 302591624 by methyl on Friday 20th of January 2012 06:09:35 AM
Old 01-20-2012
You are using the Shell feature known as a "here-document". See the section about "<<" in the manual for your Shell.
The Shell will read up to the terminating word (which in your example is EOF) and present the contents on STDIN to the program which is reading from STDIN (which in your example is sqlplus).

EOF is a popular choice for the terminating word because it happens to be an acronym for End Of File and it does not occur as a command name in any mainstream computer language (including Oracle SQL). You will find on this board that many people use an exclamation mark for the terminating word. Those from a mainframe background sometimes use four asterisks because this was the convention on card-readers.

The code posted is a bit weird because the backticks are not needed or desirable. If the output was to be placed in an environment variable the backticks would be needed. There are a lot of examples on this board.

Personally I prefer to start the script with code to edit the SQL program and place the program into a file, then execute the program as a parameter to sqlplus. This makes debugging so much easier.
 

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LEARN ABOUT REDHAT

tc-choke

TC(8)								       Linux								     TC(8)

NAME

       choke - choose and keep scheduler

SYNOPSIS

       tc qdisc ... choke limit packets min packets max packets avpkt bytes burst packets [ ecn ] [ bandwidth rate ] probability chance

DESCRIPTION

       CHOKe  (CHOose  and  Keep  for responsive flows, CHOose and Kill for unresponsive flows) is a classless qdisc designed to both identify and
       penalize flows that monopolize the queue. CHOKe is a variation of RED, and the configuration is similar to RED.

ALGORITHM

       Once the queue hits a certain average length, a random packet is drawn from the queue. If both the to-be-queued and the drawn packet belong
       to  the same flow, both packets are dropped. Otherwise, if the queue length is still below the maximum length, the new packet has a config-
       urable chance of being marked (which may mean dropped).	If the queue length exceeds  max,  the	new  packet  will  always  be  marked  (or
       dropped).  If the queue length exceeds limit, the new packet is always dropped.

       The marking probability computation is the same as used by the RED qdisc.

PARAMETERS

       The parameters are the same as for RED, except that RED uses bytes whereas choke counts packets. See tc-red(8) for a description.

SOURCE

       o      R.  Pan,	B.  Prabhakar, and K. Psounis, "CHOKe, A Stateless Active Queue Management Scheme for Approximating Fair Bandwidth Alloca-
	      tion", IEEE INFOCOM, 2000.

       o      A. Tang, J. Wang, S. Low, "Understanding CHOKe: Throughput and Spatial Characteristics", IEEE/ACM Transactions on Networking, 2004

SEE ALSO

       tc(8), tc-red(8)

AUTHOR

       sched_choke was contributed by Stephen Hemminger.

iproute2							    August 2011 							     TC(8)
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