Tuesday, May 28, 2013


Sometimes developers put undocumented options in their code to help with debugging issues. This morning I came across one of such options which prints extra debug information when executing NSS queries.

First you need to disable nscd:
# svcadm disable -t name-service/cache
Then you need to set env variable debug_eng_loop to >0, for example:
# NSS_OPTIONS="debug_eng_loop=2" ping -I 1 wp.pl
NSS_retry(0): 'ipnodes': trying 'files' ... result=NOTFOUND, action=CONTINUE
NSS: 'ipnodes': continue ...
NSS_retry(0): 'ipnodes': trying 'dns' ... result=SUCCESS, action=RETURN
NSS: 'ipnodes': return.
PING wp.pl: 56 data bytes
What's good about it is that it tells you which database configured in NSS returned the result.

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