How can I make snmpwalk escape new lines in its output?

Question

I've checked the documentation but can't see anything -- does anyone know if its possible to escape the newlines returned from some OIDs?

I need to parse the output in a script and its causing me headaches.

For example:

$ snmpwalk -v2c -c public -Oq 10.0.0.1 1.3.6.1.2.1.1
SNMPv2-MIB::sysDescr.0 Cisco Internetwork Operating System Software
IOS (tm) Catalyst 4000 L3 Switch Software (cat4000-I5S-M), Version 12.2(18)EW4, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by cisco Systems, Inc.
Com
SNMPv2-MIB::sysObjectID.0 SNMPv2-SMI::enterprises.9.1.502
DISMAN-EVENT-MIB::sysUpTimeInstance 122:19:10:46.16
SNMPv2-MIB::sysContact.0 012345
SNMPv2-MIB::sysName.0 name
SNMPv2-MIB::sysLocation.0 London,uk,emea

In my code I can parse each line of the output and split it on the first space which works until I get a multiline response like the sysDescr OID above. It would be great if there was some way to actually print \n in the response instead of a real new line.

Answer 1

You can try piping your output through this sed script:

$ snmpwalk ... | sed -n '/MIB::/!{H;$g};/MIB::/{$!x;s/\n/\\n/g;ta;${x;/^$/!p;x};:a;/^$/!p}'
SNMPv2-MIB::sysDescr.0 Cisco Internetwork Operating System Software\nIOS (tm) Catalyst 4000 L3 Switch Software (cat4000-I5S-M), Version 12.2(18)EW4, RELEASE SOFTWARE (fc1)\nTechnical Support: http://www.cisco.com/techsupport\nCopyright (c) 1986-2005 by cisco Systems, Inc.\nCom
SNMPv2-MIB::sysObjectID.0 SNMPv2-SMI::enterprises.9.1.502
DISMAN-EVENT-MIB::sysUpTimeInstance 122:19:10:46.16
SNMPv2-MIB::sysContact.0 012345\nfoo\nbar
SNMPv2-MIB::sysName.0 name
SNMPv2-MIB::sysLocation.0 London,uk,emea

Here's an AWK version that's more readable, but a little longer:

$ snmpwalk ... | awk 'function printit() {printf prev; if (accum) printf "\\n" accum; print ""} !/MIB::/{accum=accum "\\n" $0} /MIB::/{if (NR>1) {printit()}; accum=""; prev=$0} END{printit()}'

Answer 2

• Try: snmpwalk --hexOutputLength=1024 .....
• Or disable line breaks: snmpwalk --hexOutputLength=0 .....

Reference:
https://it.sourceforge.net/p/net-snmp/mailman/message/16868020/
http://net-snmp.sourceforge.net/docs/man/snmp.conf.html