I'm trying to pull one line from a subprocess.check_output but so far I have no luck. I'm running a Python script and this is my code: and this is what I get back when I run the script: Now I want to get the 9th line (RMS amplitude) out of this list. I already tried something with sed but it

How to get one line from a print output in linux?

I’m trying to pull one line from a subprocess.check_output but so far I have no luck. I’m running a Python script and this is my code:

output = subprocess.check_output("sox /home/pi/OnoSW/data/opsoroassistant/rec.wav -n stat", shell=True)

and this is what I get back when I run the script:

Samples read:             80000
Length (seconds):      5.000000
Scaled by:         2147483647.0
Maximum amplitude:     0.001129
Minimum amplitude:    -0.006561
Midline amplitude:    -0.002716
Mean    norm:          0.000291
Mean    amplitude:    -0.000001
RMS     amplitude:     0.000477
Maximum delta:         0.002930
Minimum delta:         0.000000
Mean    delta:         0.000052
RMS     delta:         0.000102
Rough   frequency:          272
Volume adjustment:      152.409

Now I want to get the 9th line (RMS amplitude) out of this list. I already tried something with sed but it didnt gave anything back:

output = subprocess.check_output("sox /home/pi/OnoSW/data/opsoroassistant/rec.wav -n stat 2>&1 | sed -n 's#^RMS     amplitude:[^0-9]*([0-9.]*)$#1#p0'",stderr= subprocess.STDOUT, shell=True)

Thank You

Answer

What about grep-ing the line ?

output = subprocess.check_output("sox /home/pi/OnoSW/data/opsoroassistant/rec.wav -n stat 2>&1 | grep 'RMS     amplitude:'",stderr= subprocess.STDOUT, shell=True)

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