A simple bash parser for the acarsdec utility.
This is actually a very simple shell script for BASH that, when fed the output from acarsdec, will parse each message into separate variables (with the default, full output format of acarsdec -o2). It only depends on grep (and eventually a database client). It will echo the message data to the standard output, but will also allow you to do whatever you want with the message data. You can find a commented section of the script, which inserts the message data into a plain table on a remote MySQL database. Just modify this part and comment out the echo statements to fit your needs.
Example usage: ./acarsdec -p 20 -r 0 131.725 | ./acars-parser.sh
Feeding a sample file: cat sample.txt | ./acars-parser.sh
Use this script at your own risk. It is more of a quick hack rather than a solid piece of code and may have issues. It is not fool proof and does not do a good job at checking the input for errors. If you spot anything suspicious, let me know, and I'll also be happy to accept pull requests with improvements.
But when you look at the code, keep in mind that I'm not a big friend of bash. :)
The script relies on a blank line to be output by acarsdec in order to determine that a message is complete. While acarsdec separates messages with a blank line, it seems it outputs the blank line only when a new message is received. If messages with a blank "Message" field are received, this is not a problem (as there are 2 empty lines) but if a "Message" is available, it means that the output will only be parsed/fed to the database as soon as another message is received. Not sure how to address this yet...
A friend of mine asked me for help setting up acarsdec with a USB DVB-T dongle on Raspberry Pi. If you don't know what ACARS is, this is probably not going to be useful to you.
While acarsdec 3.0 is a nice little utility, it is not very flexible with its output. It can either print the ACARS messages it receives to stdout, log them into a file, or feed them via UDP to another application over the network (using plane plotter or its native format). In version 3.0, it actually comes with a small server (acarsserv) via UDP, which is capable of filtering the messages and storing them into a SQLite database.
This is all nice and cool, but what we actually needed was to feed the received messages over to a remote database with the least hassle, and keep the Pi acting only as a receiver. Writing a simple bash parser seemed the most straightforward way, although the more correct approach would probably be to modify acarsdec to output the messages in another format (such as CSV or something) which would be easier to parse. But I haven't touched C in a while... It is worth noting that acarsdec does support a one-line-per-message output format (parameter -o1) but it seems it doesn't include all fields ("Block ID" and "Ack" are left out) and also the messages themselves are trimmed / shortened.