Content of RPM nagios-devel-4.4.14-4.el9.x86_64.rpm :
/usr/include/nagios
/usr/include/nagios/archivejson.h
/usr/include/nagios/archiveutils.h
/usr/include/nagios/broker.h
/usr/include/nagios/cgiauth.h
/usr/include/nagios/cgiutils.h
/usr/include/nagios/comments.h
/usr/include/nagios/common.h
/usr/include/nagios/defaults.h
/usr/include/nagios/downtime.h
/usr/include/nagios/getcgi.h
/usr/include/nagios/jsonutils.h
/usr/include/nagios/lib
/usr/include/nagios/lib/bitmap.h
/usr/include/nagios/lib/dkhash.h
/usr/include/nagios/lib/fanout.h
/usr/include/nagios/lib/iobroker.h
/usr/include/nagios/lib/iocache.h
/usr/include/nagios/lib/kvvec.h
/usr/include/nagios/lib/libnagios.h
/usr/include/nagios/lib/lnag-utils.h
/usr/include/nagios/lib/nsock.h
/usr/include/nagios/lib/nspath.h
/usr/include/nagios/lib/nsutils.h
/usr/include/nagios/lib/nwrite.h
/usr/include/nagios/lib/prqueue.h
/usr/include/nagios/lib/runcmd.h
/usr/include/nagios/lib/skiplist.h
/usr/include/nagios/lib/snprintf.h
/usr/include/nagios/lib/squeue.h
/usr/include/nagios/lib/t-utils.h
/usr/include/nagios/lib/worker.h
/usr/include/nagios/locations.h
/usr/include/nagios/logging.h
/usr/include/nagios/macros.h
/usr/include/nagios/nagios.h
/usr/include/nagios/nebcallbacks.h
/usr/include/nagios/neberrors.h
/usr/include/nagios/nebmods.h
/usr/include/nagios/nebmodules.h
/usr/include/nagios/nebstructs.h
/usr/include/nagios/netutils.h
/usr/include/nagios/objectjson.h
/usr/include/nagios/objects.h
/usr/include/nagios/perfdata.h
/usr/include/nagios/shared.h
/usr/include/nagios/sretention.h
/usr/include/nagios/statusdata.h
/usr/include/nagios/statusjson.h
/usr/include/nagios/workers.h
/usr/lib64/nagios/libnagios.a