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7thSon

Member

Registered: 2017-05-07

Posts: 186

[SOLVED] How to script device detection with bluetootctl scan

I'm trying to write a script that interacts with bluetoothctl so that I do these steps:

1. Disable one of 2 controllers (I have builtin BT as well as a dongle, I want to use the dongle)
2. Scan for devices, until a specific headset is found
3. Pair with the device after it's found
4. Trust the device after pairing

I'm especially looking at step 2 since the behavior of bluetoothctl makes it a bit tricky.
Running `bluetoothctl scan on` starts the application, but the output doesn't stop until I exit out with ctrl-c, and is not possible to grep.
Are there any methods/workarounds that I could use to be able to essentially do some equivalent of `bluetoothctl scan on | grep XX:XX:XX:XX:XX:XX`, so that I can wait only until the device is detected, and then proceed with the rest of the commands?
For instance, does bluetoothctl write the scan results to a temporary file that could be checked for the mac address?

Last edited by 7thSon (2021-09-30 17:23:53)

7thSon

Member

Registered: 2017-05-07

Posts: 186

Re: [SOLVED] How to script device detection with bluetootctl scan

I can answer my own question here after some lucky research.
The tool to use here is `expect`, which allows me to interact exactly like I want to with the bluetoothctl console:

#!/usr/bin/env bash

device="00:1B:66:88:1D:52"
/usr/bin/expect <(
	cat <<EOF
set timeout 60
spawn bluetoothctl
send -- "scan on\r"
expect "$device"
send -- "pair $device\r"
expect "Pairing successful"
send -- "connect $device\r"
expect "Connection successful"
send -- "trust $device\r"
expect "trust succeeded"
send -- "exit\r"
expect eof
EOF
)

Raynman

Member

Registered: 2011-10-22

Posts: 1,539

Re: [SOLVED] How to script device detection with bluetootctl scan

Unnecessarily ugly/complex, though. Better would be

#!/usr/bin/env bash

device="00:1B:66:88:1D:52"
/usr/bin/expect -f - <<EOF
# ...
EOF

But Tcl has variables too, so you don't need bash at all:

#!/usr/bin/expect -f

set device "00:1B:66:88:1D:52"
# ...

7thSon

Member

Registered: 2017-05-07

Posts: 186

Re: [SOLVED] How to script device detection with bluetootctl scan

Unnecessarily ugly/complex, though. Better would be

#!/usr/bin/env bash

device="00:1B:66:88:1D:52"
/usr/bin/expect -f - <<EOF
# ...
EOF

But Tcl has variables too, so you don't need bash at all:

#!/usr/bin/expect -f

set device "00:1B:66:88:1D:52"
# ...

Ah thanks, I was just following along with some examples, so didn't really dive into the capabilities of expect.
I'll be sure to update this to simplify it!