How do i cut section with start and end using Bash? - linux

Question

When i am doing pactl list i get lot of information. Out of those information, i am trying to only get the part start with Sink #0 till end of that section.
1) Information's
Sink #0
State: SUSPENDED
Name: auto_null
Description: Dummy Output
Driver: module-null-sink.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 14
Mute: no
Volume: 0: 0% 1: 0%
0: -inf dB 1: -inf dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor Source: auto_null.monitor
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = "Dummy Output"
device.class = "abstract"
device.icon_name = "audio-card"
Source #0
State: SUSPENDED
Name: auto_null.monitor
Description: Monitor of Dummy Output
Driver: module-null-sink.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 14
Mute: no
Volume: 0: 80% 1: 80%
0: -5.81 dB 1: -5.81 dB
balance 0.00
Base Volume: 100%
0.00 dB
Monitor of Sink: auto_null
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = "Monitor of Dummy Output"
device.class = "monitor"
device.icon_name = "audio-input-microphone"
2) I am trying, such as:
#!/bin/bash
command=$(pactl list);
# just get Sink #0 section not one line
Part1=$(grep "Sink #0" $command);
for i in $Part1
do
# show only Sink #0 lines
echo $i;
done
3) It output very strange
grep: dB: No such file or directory
How can i get that section using my BASH script, is there any other best way to work on such filtering?
Follow up: So i was also trying to keep it simple. such as:
pactl list | grep Volume | head -n1 | cut -d' ' -f2- | tr -d ' '
|________| |________| |______| |_____________| |_________|
| | | | |
command target get show 1 row cut empty Dont know..
to list

Answer 1

You can use several features of the sed editor to achieve your goal.
sed -n '/^Sink/,/^$/p' pactl_Output.txt
-n says "don't perform the standard option of printing each line of output
/^Sink/,/^$/ is a range regular expr, that says find a line that begins with Sink, then keep looking at lines until you find an empty line (/^$/).
the final char, p says Print what you have matched.
If there are spaces or tabs on the empty line, use " ...,/^$[${spaceChar}${tabChar}]*\$/p". Note the change from single quoting to dbl-quoting which will allow the variables ${spaceChar} and ${tabChar} to be expanded to their real values. You may need to escape the closing '$'. YOu'll need to define spaceChar and tabChar before you use them, like spaceChar=" " . No way here on S.O. for you to see the tabChar, but not all sed's support the \t version. It's your choice to go with pressing tab key or use \t. I would go with tab key as it is more portable.
While it is probably possible to accomplish your goal with bash, sed was designed for this sort of problem.
I hope this helps.

Answer 2

Try:
Part1=`echo $command | grep "Sink #0"`
instead of
Part1=$(grep "Sink #0" $command);