rmqcat

rmqcat

A netcat-like tool for sending things through RabbitMQ.

Installation

npm install -g rmqcat
rmqcat --help

Use

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.

Common to both modes

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.

Duplex

# 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 argument following and redirect stdin and stdout of that process to 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".

One-way

# 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.