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Old 10-09-2017, 02:10 PM   #1
Jason_25
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Control bluetoothctl with scripting?


I am trying to interact with bluetoothctl through scripting. Such as shown in these threads:
https://stackoverflow.com/questions/...alent-commands
https://stackoverflow.com/questions/...er-interaction

Code:
bluetoothctl << EOF \n pair 54:46:6B:01:6C:CC \n EOF
result: > is displayed and nothing happens

Code:
echo -e 'pair 54:46:6B:01:6C:CC' | bluetoothctl
result: command is entered and bluetoothctl immediately quits without waiting for the pin prompt so it can be captured

Code:
bluetoothctl <<< 'pair 54:46:6B:01:6C:CC'
result: command is entered and bluetoothctl immediately quits without waiting for the pin prompt so it can be captured

What is the solution here?

edit: Fixed.

I tried to use:
Code:
hcitool cc <bdaddr>; hcitool auth <bdaddr>
This always failed.

I then tried to use screen which was similar to the second two problems above in that the bluetoothctl just quits immediately. I also spent some time needlessly trying to manipulate the file handlers for the process in /proc but ultimately that just writes to the screen not the program itself. Finally the answer was to use Tmux as so:
Code:
tmux new-session -d -s ServerFault 'sudo bluetoothctl -a |& tee /run/shm/BLUETOOTH_OUTPUT'
To send commands:
Code:
tmux send-keys -t ServerFault -l 'pair BT_MAC_OF_SLAVE_GOES_HERE'
tmux send-keys -t ServerFault Enter
To debug you can tmux attach-session -t ServerFault or cat /run/shm/BLUETOOTH_OUTPUT.

Notes: I had to remove all the tr and a through z stuff. Just by accident I stumbled upon the |& tee stuff. That is required because a normal redirect to file does not work and is blank. I chose /run/shm because at least on the Raspberry Pi that is where RAM files are stored. The word ServerFault can be anything you like. I think the newest version of Bluez may have a different, possibly better utility for doing this. As far as bluetoothctl itself goes it takes more to actually do anything than the examples here. It also takes way more to actually write a script that can handle Bluetooth connections through bluetoothctl but hopefully this gets you started on one or allows you to work up a simple solution.

References:
https://serverfault.com/questions/17...a-screen-sessi
https://www.reddit.com/r/tmux/commen...zh&sh=48426000

Last edited by Jason_25; 10-09-2017 at 10:16 PM.
 
Old 10-16-2017, 11:11 PM   #2
firstfire
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Hi.

In bash you can use e.g. coproc to start and communicate with another process:
Code:
#!/bin/bash

coproc bluetoothctl
echo -e 'info 54:46:6B:01:6C:CC\nexit' >&${COPROC[1]}
output=$(cat <&${COPROC[0]})
echo $output
Here COPROC is a two-element array containing output/input file descriptors respectively. See the Coprocesses section of man bash for details.
 
Old 05-03-2018, 06:44 AM   #3
pantiri
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Hi,
seems that your answer cannot be working in a script, but only via command line
i faild to launch a script that executes coproc command
 
Old 05-04-2018, 05:35 AM   #4
firstfire
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Hi.

Welcome to LQ!

It works for me (in the sense that it is possible to interact with background process; it's up to you what exactly you'll do with bluetoothctl) so make sure that

1. You made the script executable (chmod +x script.sh)
2. Your version of bash supports coproc (help coproc; Coprocesses section in man bash)
3. bluetoothctl is actually installed and working.
4. bluetoothctl adds color codes and other control characters to output which may lead to strange results (e.g. it may appear that there are no output at all -- pipe to less or hd to see that it's there). To alleviate this one may use sed, for instance
Code:
$ /tmp/test.sh | sed 's/\x1B\[[0-9;]*[JKmsu]//g; s/\r/\n/g'
Waiting to connect to bluetoothd...
[bluetooth]#
[NEW] Controller C4:85:08:A0:67:51 alar [default] [bluetooth]#
[NEW] Device 1C:52:16:9A:DC:D5 QCY-QY19 [bluetooth]#
[NEW] Device 9C:DF:03:0E:C7:EC harman BT [bluetooth]#
[NEW] Device 00:0D:18:A1:50:2F MMC12 [bluetooth]# info 54:46:6B:01:6C:CC Device 54:46:6B:01:6C:CC not available [bluetooth]# exit [bluetooth]#
[DEL] Controller C4:85:08:A0:67:51 alar [default] [bluetooth]#

Waiting to connect to bluetoothd...
 
Old 05-04-2018, 06:19 AM   #5
pantiri
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Registered: May 2018
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Hello
Many thanks for your answer and help
actually it's working in command line, so i think coproc is supported and bluetoothctl is installed and working
When I launch it in command line, line by line it works
Then I create a simple script, I make it executable with others simple commands like echo.. I can see echo results
But when I check the process I see that coproc bluetoothctl has not been launched
and so I have help coproc showing this
i@pi3_portail:~/script_py$ help coproc
coproc: coproc [NAME] command [redirections]
Create a coprocess named NAME.

Execute COMMAND asynchronously, with the standard output and standard
input of the command connected via a pipe to file descriptors assigned
to indices 0 and 1 of an array variable NAME in the executing shell.
The default NAME is "COPROC".

Exit Status:
The coproc command returns an exit status of 0.
 
Old 05-04-2018, 06:21 AM   #6
pantiri
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So i thing, from your answer, the point 1, 2, 3 are OK
For the point 4.. not very clear for me sorry
 
  


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