路徑（不存在請先建立路徑）：
/etc/portage/package.use/
建立一個任意名稱檔案：
nano /etc/portage/package.use/list
格式範例：
www-servers/nginx aio -pcre2 pcre-jit rtmp
net-misc/wget cookie-check idn metalink _ntlm
sys-apps/util-linux fdformat magic
net-misc/openssh ldns kerberos ldns -security-key
sys-fs/cryptsetup fips ssh
dev-libs/libcbor custom-alloc
app-arch/libarchive nettle
sys-apps/shadow bcrypt
sys-devel/gcc fortran -go graphite jit -lto -pgo vtv
app-editors/nano justify magic
dev-vcs/git -perl
#dev-db/postgresql perl
sys-kernel/linux-firmware initramfs savedconfig
net-misc/dhcpcd udev
sys-boot/grub -fonts -themes mount -truetype
sys-libs/glibc nscd suid
sys-devel/binutils gold multitarget
media-libs/libmetalink expat -xml
net-nds/openldap tcpd argon2 autoca overlays pbkdf2 sasl sha2
dev-libs/modsecurity fuzzyhash geoip geoip2 json lmdb lua pcre2
net-misc/curl alt-svc gnutls gopher hsts mbedtls nss quiche rtmp sslv3