测试和记录终端输出

Question

I am using the following command line in order to send command to my device controller thru bluetoothctl tool.

#!/bin/sh
{ sleep 1 && echo -e 'power on \n' && sleep 1;} | bluetoothctl

Which returns in the terminal :

root@snp:~# ./bt.sh 
[NEW] Controller 01:02:03:04:05:C3 snp [default]
[NEW] Device 98:0D:2E:E5:14:81 HTC
Changing power on succeeded
[CHG] Controller 01:02:03:04:05:C3 Powered: yes
[DEL] Controller 01:02:03:04:05:C3 snp [default]

I would like to reduce and manage the number of messages returned. Basically, I want to display on screen and store in a log file :

Changing power on succeeded
[CHG] Controller 01:02:03:04:05:C3 Powered: yes

I enter

{ sleep 1 && echo -e 'power on \n' && sleep 1;} | bluetoothctl | grep -E "Changing|[CHG]" 2>&1 | tee log.txt

But I obtain,

root@snp:~# ./bt.sh 
[NEW] Controller 01:02:03:04:05:C3 snp [default]
[NEW] Device 01:02:03:04:05:C3 HTC 
Changing power on succeeded
[DEL] Controller 01:02:03:04:05:C3 snp [default]

Where is my fault ?

In addition, is it possible to test if Powered = yes or not thru a conditional test, and all stuff do in the same line ?

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Edit n°1 :

Indeed, the status messages are not directed to standard error, 2>&1 was useless.

However, I tried your proposition by means of :

{ sleep 1 && echo -e 'power on \n' && sleep 1;} | bluetoothctl | grep -E 'Changing|\[CHG]' 

which always returns

root@snp:~# ./bt.sh 
Changing power on succeeded

Instead of

root@snp:~# ./bt.sh 
Changing power on succeeded
[CHG] Controller 01:02:03:04:05:C3 Powered: yes

Answer 1

The regex [CHG] is a character class which matches any one of C , H , or G . If you want to match an opening square bracket literally, you have to escape it.

grep -E 'Changing|\[CHG]'

In addition, you might want to check whether the status messages are being directed to standard error. If so, try

... | bluetoothctl 2>&1 | grep ...

The grep 2>&1 redirection you have does not seem to serve any useful purpose.