A netcat-like tool for sending things through RabbitMQ.
npm install -g rmqcat
rmqcat --help
rmqcat
has two modes of use, one-way and two-way ("duplex"). Duplex
corresponds more or less to how netcat
works, that is, it
establishes a socket-like connection with a server ('listener') on one
side and a client on the other, which can speak back and forth.
One-way (simplex) either relays stdin to a RabbitMQ queue, or from a RabbitMQ queue to stdout. Sending to a queue doesn't wait for a receiver; receiving from a queue waits for data in the queue.
The option --url
can be used to address a specific RabbitMQ server,
and to provide connection parameters -- see the amqplib
documentation. By default a RabbitMQ server on
localhost is assumed, so you will probably want to supply --url
in
practice.
The option -D
will make rmqcat output a bit of debug information to
stderr.
The option --help
, if present at all, will make rmqcat output a
usage message to stderr then exit.
# Start a listener that will put whatever it gets in a file
rmqcat -l > recv.txt
# Send a file to the listener
rmqcat < send.txt
rmqcat
used this way will keep a connection open until it gets
end-of-file, so you can use it to "chat" back and forth, similar to
netcat.
A client (i.e., without -l
) will buffer input until its connection
is accepted by a listener.
The option -k
in combination with -l
will keep the listener
accepting successive connections. Otherwise it will exit once the
first connection closes.
The option -e
or --exec
causes rmqcat to spawn a child process
using the remainder of the arguments, and redirect stdin and stdout of
that process tthrough the queue. For example,
rmqcat -l --exec grep -n foo
If the option -k
is used in combination with -e
, the child process
will be run for each connection made. In a client, the process is run
once the connection is accepted.
The option --service
has a role similar to a TCP port number. It
names a queue to be used by clients and listeners to establish
connections. The default is arbitrarily "rmqcat"
.
# Send a file to a queue
rmqcat --send bobbins < bobbins.iso
# Save the file in a queue and output the SHA1 sum
rmqcat --recv bobbins | tee bobbins.iso | shasum
The string following either --send
or --recv
names a queue that
will hold the data in transit. More than one file of data can be
present in the queue; rmqcat --recv <queue>
will read a single file
before exiting, or wait if there is no data yet.