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Full Discussion: what does this command do?
Top Forums Shell Programming and Scripting what does this command do? Post 302190399 by era on Tuesday 29th of April 2008 02:30:06 PM
Old 04-29-2008
exec in this form is for redirecting the file descriptors of the process.

Think of it this way; if you always want to do "myscript 2>/tmp/fnord 1>&2" then you can say this inside myscript, right at the beginning:

Code:
exec 2>/tmp/fnord 1>&2

Then the redirections are no longer needed at the prompt when you run myscript.

So in your example, the script's input file descriptor (what every command will be reading from if not given a file argument -- read, cat, grep, you name it) from that point on is /dev/console, output from all commands will go to /dev/console (unless separately redirected, of course), and errors will go to the same (2>&1 means send standard error where-ever standard output is).
 

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AMQP-CONSUME(1) 						 RabbitMQ C Client						   AMQP-CONSUME(1)

NAME
amqp-consume - Consume messages from a queue on an AMQP server SYNOPSIS
amqp-consume [OPTION...] {command} [args...] DESCRIPTION
amqp-consume consumes messages from a queue on an AMQP server. For each message that arrives, a receiving command is run, with the message body supplied to it on standard input. amqp-consume can consume from an existing queue, or it can create a new queue. It can optionally bind the queue to an existing exchange. By default, messages will be consumed with explicit acknowledgements. A message will only be acknowledged if the receiving command exits successfully (i.e. with an exit code of zero). The AMQP "no ack" mode (a.k.a. auto-ack mode) can be enable with the -A option. OPTIONS
-q, --queue=queue name The name of the queue to consume messages from. If the --queue option is omitted, the AMQP server will assign a unique name to the queue, and that server-assigned name will be dixsplayed on stderr; this case implies that an exclusive queue should be declared. -e, --exchange=exchange name Specifies that an exclusive queue should be declared, and bound to the given exchange. The specified exchange should already exist unless the --exchange-type option is used to request the creation of an exchange. -r, --routing-key=routing key The routing key for binding. If omitted, an empty routing key is assumed. -d, --declare Forces an exclusive queue to be declared, even when it otherwise would not be. That is, when a queue name is specified with the --queue option, but no binding to an exchange is requested with the --exchange option. -A, --no-ack=routing key Enable "no ack" mode: The AMQP server will unconditionally acknowledge each message that is delivered, regardless of whether the target command exits successfully or not. EXAMPLES
Consume messages from an existing queue "myqueue", and output the message bodies on standard output via cat: $ amqp-publish -q myqueue cat Bind a new exclusive queue to an exchange "myexch", and send each message body to the script myscript, automatically acknowledging them on the server: $ amqp-consume -A -e myexch ./myscript SEE ALSO
librabbitmq-tools(7) describes connection-related options common to all the RabbitMQ C Client tools. AUTHOR
The RabbitMQ Team <info@rabbitmq.com> RabbitMQ C Client 2011-01-01 AMQP-CONSUME(1)
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