Man pages matching name setlinebuf in section 3:

setlinebuf.3.de	debian 10 / manpages-de-dev
setlinebuf.3.en	debian 10 / manpages-dev
setlinebuf.3.es	debian 10 / manpages-es
setlinebuf.3.ja	debian 10 / manpages-ja-dev
setlinebuf.3.zh_CN	debian 10 / manpages-zh
setlinebuf.3.zh_TW	debian 10 / manpages-zh
setlinebuf.3.de	debian 11 / manpages-de-dev
setlinebuf.3.en	debian 11 / manpages-dev
setlinebuf.3.es	debian 11 / manpages-es-dev
setlinebuf.3.fr	debian 11 / manpages-fr-dev
setlinebuf.3.ja	debian 11 / manpages-ja-dev
setlinebuf.3.zh_CN	debian 11 / manpages-zh
setlinebuf.3.zh_TW	debian 11 / manpages-zh
setlinebuf.3.de	debian 12 / manpages-de-dev
setlinebuf.3.en	debian 12 / manpages-dev
setlinebuf.3.ja	debian 12 / manpages-ja-dev
setlinebuf.3.zh_CN	debian 12 / manpages-zh
setlinebuf.3.zh_TW	debian 12 / manpages-zh