mjhjmtu

I am trying to make an AV bug raspberry pi for a class.

I am using sox to record sound.
Which is working fine.

the issue is sox needs to be stopped by a control+C to stop and create the new file. If killall is sent from a different ssh session it will drop the other session and sox will not create the file.

listen.sh

#! /bin/bash
NOW=$( date '+%F_%H:%M:%S' )

filename="/home/pi/gets/$NOW.wav"

sox -t alsa plughw:1 $NOW.wav;

sleep 6;

echo $filename

I have tried making a separate script for stopping it; pretty much

killlisten.sh

#! /bin/bash
sleep 5;
ps | grep sox | kill 0;

Then run a

superscript.sh

#! /bin/bash
./listen.sh;
./killlisten.sh;

Any advice on how to stop sox in a way that would still produce an output file would be great. This will ideally be set to run at set times so avoiding human interaction is essential.

Your pipeline

ps -aux | grep sox | kill 0

will not do what you want to do. This is because kill won't ever read the input from grep (the result from grep will also contain a lot of other things than just the PID of the sox process).

If you have pkill, just do

pkill sox

instead (use pkill -INT sox to send the same signal as Ctrl+C does).

If you change your startup script to

#!/bin/bash

NOW=$( date '+%F_%H:%M:%S' )

filename="/home/pi/gets/$NOW.wav"
sox -t alsa plughw:1 "$NOW.wav" & sox_pid="$!"

printf 'sox pid is %dn' "$sox_pid"

wait

# Alternatively (instead of "wait", if you want to kill sox after six seconds):
# sleep 6 && kill "$sox_pid" 

echo "$filename"

You will get the PID of the sox process printed to the terminal and you could use that to do kill pid (with pid replaced by that number).

Using & ofte the sox invocation places it in the background. The PID of that background task is automatically stored in $! and the code above assigns it to sox_pid which is later printed.

The wait command waits for the sox command (running in the background) to finish.

As we discussed in a previous session: Double-quote all variable expansions.

kill -SIGINT <pid>
is the usual equivalent to ^C.

use trapping:

#!/bin/bash

# this is a trap for ctrl + c 
trap ctrl_c INT

function ctrl_c() 

 echo "Trap: CTRL+C received, exit"
 exit