Variable assignment inside awk


 
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# 1  
Old 04-10-2013
Variable assignment inside awk

Hi,

Was hoping someone could help with the following:

Code:
while read line; do pntadm -P $line | awk '{if (( $2 == 00 && $1 != 00 ) || ( $2 == 04 )) print $3,$5}'; done < /tmp/subnet_list

Anyone know if it is possible to assign $3 and $5 to separate variables within the {} brackets?

Thanks in advance
CiCa
# 2  
Old 04-10-2013
This will go much faster if you explain what it is you are trying to accomplish. Perhaps demonstrate a failed attempt and explain why it was inadequate.

The answer to your question as asked is an obvious yes. The value of the field variables $3 and $5 can be assigned to separate variables (although they already are in separate variables). Perhaps you meant if those values could be pulled out of AWK and assigned to shell variables?

Again, this will go much faster if you explain the bigger picture.

Regards,
Alister
# 3  
Old 04-10-2013
Hi Alister,

Essentially what I am trying to get here is pick out list of IP addresses from dhcp pool on a Solaris (dhcp) server where certain criteria are matched.

/tmp/subnet_list - contains a list of subnets

The pool for each subnet is listed and each line (containing an IP address among other details) is checked.

I am trying to match each line that has a MAC address present AND a reserved flag of 00 (awk variables $1 and $2 respectively) OR has a reserved flag of 04 (again awk variable $1).

For each of the lines that are matched, I want to pass the awk variables $3 and $5 (of the line in question) out to a shell variable e.g. ip_address=$3 and lease_date=$5. So I can then pass these through another check...

I hope this helps explain things a little better and unfortunately I can not provide code examples at this point in time, as I do not have access to the script from the system I am presently using.

If further details are required, let me know...

Thanks in advance
CiCa
# 4  
Old 04-10-2013
Here's a possible way, in a shell script:
Code:
rm -f /tmp/awk_output
while read line; do
  pntadm -P $line | awk '{if (( $2 == 00 && $1 != 00 ) || ( $2 == 04 )) print $3,$5}' >> /tmp/awk_output
done < /tmp/subnet_list

while read ip_address lease_date; do
  echo $ip_address lease_date
  # further ops
done < /tmp/awk_output

# 5  
Old 04-11-2013
Thanks Hanson44 - I could do it that way, but I was really hoping to assign $3 and $5 to shell variables inside the {} brackets (assuming that it is actually possible?)...

Just to make the picture a little clearer:
Code:
root[my-box]# cat /tmp/final_list
111.222.333.0
root[my-box]# pntadm -P 111.222.333.0 | head

Client ID       Flags   Client IP       Server IP       Lease Expiration                Macro           Comment

00A0BCDE1FGHI1  00      111.222.333.001    111.222.333.253     04/06/2013                      macro1
00              04      111.222.333.002    111.222.333.253     Zero                            macro1
00              00      111.222.333.003    111.222.333.253     Zero                            macro1
00A0BCDE1FGHI2  00      111.222.333.004    111.222.333.253     05/06/2013                      macro1
root[my-box]#

Present code:
Code:
while read line; do pntadm -P $line | awk '{if (( $2 == 00 && $1 != 00 ) || ( $2 == 04 )) print $3,$5}'; done < /tmp/subnet_list

The code I have a present should pick out three lines from above (IP's 111.222.333.001 ...002 and ...004).

Can anyone tell me how to assign $3 and $5 to shell variables, within the {} brackets - please? Smilie

Rgds
CiCa

Last edited by CiCa; 04-11-2013 at 05:50 AM..
# 6  
Old 04-11-2013
Use array
Code:
while read line; do 
  val=( pntadm -P $line | awk '{if (( $2 == 00 && $1 != 00 ) || ( $2 == 04 )) print $3,$5}' )
  echo ${val[0]} ${val[1]}
done < /tmp/subnet_list

--ahamed
# 7  
Old 04-11-2013
Thanks Ahamed101 - unfortunately though, my knowledge around arrays and their usage is pretty limited e.g. how do I then read these values out of the array?

Alternatively, do you know of a way of doing this without the use of an array?

Thanks
CiCa
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