Re: nawk doesn't match mac addresses with quantifiers

Robert Langdon wrote:
> Dear Community,
> 
> Using quantifiers as shown in the code below doesn't match mac addresses

> from the input file.
> 
> Neither...
> 
> #!/usr/bin/nawk -f
> /([0-9a-fA-F][0-9a-fA-F]:){5}([0-9a-fA-F][0-9a-fA-F])/ {
>  print $1
> }
> 
> nor
> 
> #!/usr/bin/nawk -f
> /[0-9a-fA-F][0-9a-fA-F]:{5}[0-9a-fA-F][0-9a-fA-F]/ {
>  print $1
> }
> 
> match any line.

I don't believe nawk supports RE intervals (e.g. {5}). GNU awk supports
it if you use the --re-interval option. /usr/xpg4/bin/awk is, I think, a
POSIX awk and so should support it like any POSIX awk would.

> cat input_file.lst
> 00:01:96:b5:bb:ab  ANYTEXTA         Associated     7     Yes   802.11b  
29
> 00:03:66:aa:c2:02  ANYTEXTB         Associated     4     No    802.11b  
29
> 00:11:cf:df:65:66  ANYTEXTC         Associated     4     No    802.11b  
29
> 00:f0:f8:00:67:33  ANYTEXTD         Associated     4     No    802.11b  
29
> 
> The code below, without quantifiers, match the mac address properly.
> #!/usr/bin/nawk -f
>
/[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]:[0-9a-fA-F][0-9a-fA-F]/

> {
>  print $1
> }
> 
> Any ideas how to create a proper pattern with quantifiers to match a mac

> address?

gawk --re-interval 
'/^([[:xdigit:]][[:xdigit:]]:){5}[[:xdigit:]][[:xdigit:]]/ {
print $1
}'

or:

awk 'BEGIN{x="[[:xdigit:]]"; d=x x; a=d":"d":"d":"d":"d":"d}
$1 ~ a { print $1 }'

Regards,

	Ed.