jackrec man page
jackrec — JACK toolkit client for recording audio
jackrec -f filename -d seconds [ -b bitdepth ] port1 [ port2 ... ]
jackrec is a basic, but useful, audio recorder that will record audio from 1 or more JACK ports to a file on disk. The file format is always RIFF/WAV, with samples stored as signed integers. The sample bit depth can be selected using the -b option. The file will have as many channels as there are ports specified on the command line - each channel will contain the data recorded from one port. The user should generally specify the duration (in seconds) using the -d option. If not specified, jackrec will record until terminated by a signal (eg. from Ctrl-c).
This application is not intended to be a heavy duty audio recorder, and originated as an example client to show how to handle threading and disk I/O in a JACK client. However, it is a useful, simple recorder and is included in the JACK toolkit as a result.