use.conf

The use.conf file controls which use flags are and are not enabled. It is a standard configuration file which may be a bash file (use.bash) and which may use the use.conf.d/ directory.

Each line in the file consists of a specification followed by one or more use flags and labels. A specification may be any of:

• The special specification */*, which matches all packages. Nearly all users will have at least one line using this specification.
• A simple category/package name.
• A simple set name.
• A complex dependency specification.

Any token may be quoted using either single or double quotes.

A use flag or label can be:

• flag, which enables that flag.
• -flag, which disables that flag.
• LABEL:, which marks any subsequent flags on that line as applying to a particular use expand label. Common examples of use expand labels are VIDEO_CARDS, LINGUAS and INPUT_DEVICES.
• -*, which disables all flags for the current label, or all flags that are not a label if there is no current label.

Use flag settings are cumulative. This applies to expanded use flags too, so if you do not wish to inherit, say, default VIDEO_CARDS from your profile, you will need to use */* VIDEO_CARDS: -* radeon.

Example

# Accept some basic defaults for all packages, inheriting defaults from profiles
*/* -doc -nls -apache2 bash-completion -gnome -kde mpd flac aac cdparanoia \
  mmx mmxext rtc sse -arts -qt3 -cups real dvd threads dvdnav mp3 quicktime \
  pnm real vidix a52 3dnow 3dnowext amr bidi bl cddb dts srt unicode xvmc

# And set some USE_EXPAND defaults for all packages, explicitly overriding defaults
# from profiles
*/* LINGUAS:           -* en_GB en
*/* VIDEO_CARDS:       -* nv nvidia
*/* ALSA_CARDS:        -* emu10k1

# Some per package settings
app-editors/vim        -perl -python
app-crypt/gnupg        -X
media-sound/lame       -gtk

# And some wildcarding
dev-cpp/*              doc