mjhjmtu

I have to extract from the command hcitool dev only the MAC address of the bluetooth dongle.

Output of hcitool dev is:

Devices:
hci0 xx:xx:xx:xx:xx:xx

I write this output to a file and try to get the info with awk:

hcitool dev > /home/pi/mario/BT.txt
awk ' print $2 ' /home/pi/mario/BT.txt

The output also contains the first row which is an empty cell:

xx:xx:xx:xx:xx:xx

How can I put off the first cell?

For you purpose is quite enough grep

hcitool dev | grep -o "[[:xdigit:]:]11,17"

-o outputs just finded patten

[[:xdigit:]:] mean all hexadecimal digits plus : char

11,17 the set of chars should be neither less then 11 no more 17 in length

try

 awk 'NR>1 print $2 ' /home/pi/mario/BT.txt

where

• 
  NR>1 means skip first row. (NR: Number of record)

cut

in:

hcitool dev | cut -sf3

out:

xx:xx:xx:xx:xx:xx

hcitool dev | awk '$0=$2'

With awk and many other languages, an assignment can be used as a conditional. The value assigned is then interpreted as a boolean value (integer zero, or an empty string, is "false").

In this case, the expression $0 = $2 will be "true" is there's anything in the second column. Regardless of whether there is or not, the contents of the line, $0, will be replaced by this value.

In awk, when a condition or pattern does not have a corresponding action block ( ... ) then the default action is to output the current line, as if the action had been print $0 or just print .

This has the effect of printing the second white-space-delimited column in the input data, but only for the lines where there is actually something in the second column.

The below command displays complete details of Bluetooth like address, type, Tx bytes, Rx bytes, name, link policy, manufacturer

hciconfig -a

awk

in:

hcitool dev | awk '/hci0/ print $2'

out:

xx:xx:xx:xx:xx:xx