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Old 07-07-2010, 10:31 AM   #1
shippropeller
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BASH: output of snmpget with multiple OIDs into separate variables


Hi all

I have a problem with snmp answers being empty or having spaces.

What I already have:

#get all interface indexes (if you wonder - I'm working for a cable company and different cablemodems have different number and types of interfaces):
ifi=$(for i in $(snmpwalk -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.1); do echo -n "$i "; done)

#for every interface I want to have the status (admin and oper), speed, type, physical address (MAC address) and description
#the printf command gives me a nice table of all the interfaces and their respective values
for i in ${ifi}
do
read -d "\e" ifadm ifoper ifspeed iftype ifphys < <(snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.7.$i .1.3.6.1.2.1.2.2.
1.8.$i .1.3.6.1.2.1.2.2.1.5.$i .1.3.6.1.2.1.2.2.1.3.$i .1.3.6.1.2.1.2.2.1.6.$i)
ifdescr=$(snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.2.$i)
printf "%+3s |%+5s |%+8s | %+10s | %-40s | %-20s | %s\n" "${i}" "${ifadm}" "${ifoper}" "${ifspeed}" "${ifdescr}" "${iftype}" "${if
phys}"
done

The problem is the physical address which is sometimes empty and the description which has spaces.
So I'm doing 2 snmpgets which is slower than 1 snmpget (sometimes I have up to 18 interfaces).


I'm trying to explain it a bit simpler.
Interface 5 gives me back the following lines:

user@host:~$ snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.7.5 .1.3.6.1.2.1.2.2.1.8.5 .1.3.6.1.2.1.2.2.1.5.5 .1.3.6.1.2.1.2.2.1.3.5 .1.3.6.1.2.1.2.2.1.6.5 .1.3.6.1.2.1.2.2.1.2.5
up
down
1000000000
ethernetCsmacd

Ethernet CPE Interface


Now the first line should go into variable ifadm,
2nd line should go into variable ifoper,
3rd line should go into variable ifspeed,
4th line should go into variable iftype,
5th line (which is empty) should go into variable ifphys and finally
6th line (which has spaces) should go into variable ifdescr

I'm pretty sure I made it too complicated, but I don't see the simple solution.

Many thx to all the help.
 
Old 07-07-2010, 01:19 PM   #2
David the H.
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Sorry, it is a bit hard to understand exactly what you're doing. It would help readability a lot if you put [code][/code] tags around your code, to preserve formatting.

Are the entries all coming out as one-per-line? And it does output blank lines if the value is empty? If so, then you can simply set the IFS to newline, then each variable can be easily configured to catch one whole line of code. You might even consider using an array here instead. Something like:
Code:
IFS=$'\n'   #set separator to newline only

ifarray=( $(your-command-to-get-the-values) )

ifadm="${ifarray[0]}"
ifoper="${ifarray[1]}"
...etc

unset IFS

Once you have the variables properly set, there should be no problem in handling blanks, if required. Simple parameter substitution can be used to remove or convert spaces, and to output a default value if blank.
 
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Old 07-07-2010, 03:02 PM   #3
shippropeller
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Thumbs up

Sorry for posting hard to read code. I think you can look at the one-liner code which was at the bottom of the first post, the rest was "just" explanation:

Command:
Code:
user@host:~$ snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.7.5 .1.3.6.1.2.1.2.2.1.8.5 .1.3.6.1.2.1.2.2.1.5.5 .1.3.6.1.2.1.2.2.1.3.5 .1.3.6.1.2.1.2.2.1.6.5 .1.3.6.1.2.1.2.2.1.2.5
Output:
Code:
up
down
1000000000
ethernetCsmacd

Ethernet CPE Interface
Yes, all entries are coming out as one-per-line. And yes, it does output blank lines if the value is empty.

I already thank you a lot for your time and I think you are close nearby, but the blank line isn't handled as expected:

Command:
Code:
user@host:~$ IFS=$'\n' ifarray=( $(snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.7.5 .1.3.6.1.2.1.2.2.1.8.5 .1.3.6.1.2.1.2.2.1.5.5 .1.3.6.1.2.1.2.2.1.3.5 .1.3.6.1.2.1.2.2.1.6.5 .1.3.6.1.2.1.2.2.1.2.5) ); echo =0=${ifarray[0]}=; echo =1=${ifarray[1]}=; echo =2=${ifarray[2]}=; echo =3=${ifarray[3]}=; echo =4=${ifarray[4]}=; echo =5=${ifarray[5]}=
Output:
Code:
=0=up=
=1=down=
=2=1000000000=
=3=ethernetCsmacd=
=4=Ethernet CPE Interface=
=5==
So it is assigning line 6 to array index 4 insted of 5 as expected.

Well, I could do simply after the my-command-to-get-the-values:
Code:
 | sed 's/$/ /'
Or do you know here a better trick?

Once more: Many thx for your help.
 
Old 07-07-2010, 03:52 PM   #4
David the H.
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Hmm. I guess I was wrong about that then. I was pretty sure the IFS-as-newline would register during the array setting. Sorry.

I think your idea of using sed at the end is a reasonable one. I can't think of any other easy way to register the field as non-empty off the top of my head. I think I'd use a unique character or string instead of a single space though, which makes it a bit easier to substitute out again afterwards.

And by the way, you can shorten up that nasty number string with a bit of brace expansion. Or else set it ahead of time in a variable. It helps keep the code readable that way.

Code:
IFS=$'\n'

ifarray=( $(snmpget -Oqv -v 2c -c $COMMUNITY $IP .1.3.6.1.2.1.2.2.1.{2,3,5,6,7,8}.5 |sed 's/^$/empty/ ) )

echo "${ifarray[4]/empty/}"  #removes the "empty" string if it finds it
 
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Old 07-08-2010, 12:50 AM   #5
shippropeller
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Registered: Jul 2010
Location: Zurich
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Many thx for all your help!
 
  


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