CODEWITHSUNDEEP
sedsh
AdrianL
AdrianL

Reputation: 335

extracting a number in a line with sed

I'm trying to get a Value out of a information block.

I'm creating the following output: 

RSSI: -21
RSSI: -12
RSSI: -13
RSSI: -13
RSSI: -16
RSSI: -13

with following command:

hcidump -a | egrep 'RSSI|bdaddr' | grep -A1 --no-group-separator 'bdaddr XX:XX:XX:XX:XX' | egrep 'RSSI'

But i would like to get only the Value at the end to be displayed. But I'm struggling with the right pattern, I found many hints online, but not one that will work, e.g.:

sed 's/RSSI: //'

Further I would like to know if there is a smoother way of my command on the top, because it seems with every | the output is getting slower, like it fills a buffer before it outputs the values.

PS: i wanna use this command in C with the system() function, is there an option to get the value to be stored in a C-variable?

Upvotes: 1

Views: 93

Answers (3)

dr_
dr_

Reputation: 2292

No need for sed, you can use cut:

cut -d' ' -f2 myfile

This will output only the 2nd column, considering one whitespace as column delimiter.

Edit: to delete whitespaces at the beginning of each line in myfile, do this first:

sed -i 's/^ *//' myfile

Upvotes: 2

Kent
Kent

Reputation: 195029

Give this a try

hcidump -a |.. whatever...:XX:XX'|grep -Po 'RSSI:\s+\K.*'

or

hcidump -a |.. whatever...:XX:XX'|awk '/RSSI/{print $2}'

Upvotes: 2

PradeepKumbhar
PradeepKumbhar

Reputation: 3421

Or, if you have variable number of spaces in between, you can use following:

rev myfile | cut -d' ' -f1 | rev

Upvotes: 0

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