The resolver.3 man page's description of the available _res.options flag says: RES_DEBUG Print debugging messages. However, from looking at the libresolv source, I get the impression that if the library was not compiled with "DEBUG" defined then the RES_DEBUG option is silently ignored. Since it appears to be fairly common for the library to be compiled without DEBUG, it seems worth adding a note to the man page mentioning that RES_DEBUG will be ignored in that situation. (As far as I can tell from the build logs, both Debian and Ubuntu build the eglibc packages without DEBUG defined. Is there any easy way to tell on a given running system the whether libresolv was build with or without DEBUG defined?) It might also be worth mentioning the compile-time issue on the resolv.conf.5 page (in the paragraph for the "debug" option).
Thanks Nathan. I've applied the patch below. Cheers, Michael diff --git a/man3/resolver.3 b/man3/resolver.3 index 991b263..f659325 100644 --- a/man3/resolver.3 +++ b/man3/resolver.3 @@ -27,7 +27,7 @@ .\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu) .\" Modified 2004-10-31 by aeb .\" -.TH RESOLVER 3 2012-04-23 "GNU" "Linux Programmer's Manual" +.TH RESOLVER 3 2013-03-05 "GNU" "Linux Programmer's Manual" .SH NAME res_init, res_query, res_search, res_querydomain, res_mkquery, res_send, dn_comp, dn_expand \- resolver routines @@ -185,6 +185,10 @@ has been called. .TP .B RES_DEBUG Print debugging messages. +This option is only available if glibc was built with debugging enabled, +.\" See resolv/README. +.\" Support for RES_DEBUG was made conditional in glibc 2.2. +which is not the default. .TP .B RES_AAONLY Accept authoritative answers only. diff --git a/man5/resolv.conf.5 b/man5/resolv.conf.5 index 9a3ca54..1358b73 100644 --- a/man5/resolv.conf.5 +++ b/man5/resolv.conf.5 @@ -18,7 +18,7 @@ .\" .\" Added ndots remark by Bernhard R. Link - debian bug #182886 .\" -.TH RESOLV.CONF 5 2012-11-11 "" "Linux Programmer's Manual" +.TH RESOLV.CONF 5 2013-03-05 "" "Linux Programmer's Manual" .UC 4 .SH NAME resolv.conf \- resolver configuration file @@ -133,7 +133,9 @@ where \fIoption\fP is one of the following: sets .BR RES_DEBUG in -.IR _res.options . +.IR _res.options +(only effective if glibc was built with debug support; see +.BR resolver (3)). .TP .BI ndots: n .\" Since glibc 2.2