'into' function sets and exports _E_DESTTREE_ variable for usage by the following ebuild helpers: $ grep -r _E_DESTTREE_ bin/ebuild-helpers/* bin/ebuild-helpers/dobin: _E_DESTTREE_=${DESTTREE} bin/ebuild-helpers/dobin:if [[ ! -d ${ED%/}/${_E_DESTTREE_#/}/bin ]] ; then bin/ebuild-helpers/dobin: install -d "${ED%/}/${_E_DESTTREE_#/}/bin" || { __helpers_die "${0##*/}: failed to install ${ED%/}/${_E_DESTTREE_#/}/bin"; exit 2; } bin/ebuild-helpers/dobin: install -m0755 -o ${PORTAGE_INST_UID:-0} -g ${PORTAGE_INST_GID:-0} "${x}" "${ED%/}/${_E_DESTTREE_#/}/bin" bin/ebuild-helpers/dolib: _E_DESTTREE_=${DESTTREE} bin/ebuild-helpers/dolib:libdir="${ED%/}/${_E_DESTTREE_#/}/${CONF_LIBDIR}" bin/ebuild-helpers/domo: _E_DESTTREE_=${DESTTREE} bin/ebuild-helpers/domo: _E_DESTTREE_=/usr bin/ebuild-helpers/domo:if [ ! -d "${ED%/}/${_E_DESTTREE_#/}/share/locale" ] ; then bin/ebuild-helpers/domo: install -d "${ED%/}/${_E_DESTTREE_#/}/share/locale/" bin/ebuild-helpers/domo: mydir="${ED%/}/${_E_DESTTREE_#/}/share/locale/${mytiny%.*}/LC_MESSAGES" bin/ebuild-helpers/dosbin: _E_DESTTREE_=${DESTTREE} bin/ebuild-helpers/dosbin:if [[ ! -d ${ED%/}/${_E_DESTTREE_#/}/sbin ]] ; then bin/ebuild-helpers/dosbin: install -d "${ED%/}/${_E_DESTTREE_#/}/sbin" || { __helpers_die "${0##*/}: failed to install ${ED%/}/${_E_DESTTREE_#/}/sbin"; exit 2; } bin/ebuild-helpers/dosbin: install -m0755 -o ${PORTAGE_INST_UID:-0} -g ${PORTAGE_INST_GID:-0} "${x}" "${ED%/}/${_E_DESTTREE_#/}/sbin" $ grep dolib bin/ebuild-helpers/dolib.{a,so} bin/ebuild-helpers/dolib.a:LIBOPTIONS='-m0644' PORTAGE_INTERNAL_DOLIB=1 exec dolib "$@" bin/ebuild-helpers/dolib.so:LIBOPTIONS='-m0755' PORTAGE_INTERNAL_DOLIB=1 exec dolib "$@" $ This shows that 'into' function affects: dobin, dosbin, dolib, dolib.a, dolib.so, domo. domo is affected only in EAPIs older than "7". However ebuild(5) man page has this description which does not match implementation: " into <path> Sets the root (DESTTREE) for other functions like dobin, dosbin, doman, doinfo, dolib. The default root is /usr."