Re: [gentoo-user] Need help with USE options.

[Holly Bostick]

Dale schreef:
> Hi again,
>
> I read a thread that was talking about the global USE pulling some
> things a user may not want installed.  I am going to do a reinstall
> and mostly copy some things over from my current install but I do
> want to change my USE line.  I am a bit worried about using the
> option they posted, the "-*" at the beginning of the USE line.  I may
>  disable something that I need then.

The first thing you need to understand is that USE flags enable/disable
*optional* support for supplemental applications. USE flags will never
affect anything that you "need" (to run the system), though it may
affect things that you "want" (for your own ease and comfort).

For example:

I run fvwm-crystal (not KDE, thus, and also not GNOME, though GNOME is
installed). However, I do use the KDE program K3b for CD burning.


 emerge -pv k3b

These are the packages that I would merge, in order:

Calculating dependencies ...done!
[ebuild   R   ] app-cdr/k3b-0.12.10  +alsa -arts +css -debug +dvdr
+encode +ffmpeg +flac +hal -kde +kdeenablefinal +mp3 +musepack
+musicbrainz +sndfile +vcd +vorbis -xinerama 0 kB


As you can see, I have kde and arts support diasabled. Since I do not
use KDE (or even have more than a minimal KDE installed), adding such
support would be pointless (bloat), since enabling the "arts" USE flag
would bring in aRTs (the KDE sound server, which I wouldn't use even if
I did use KDE), and enabling the "kde" USE flag would bring in
"k3bSetup2", which is a nice little utility to correct the permissions
on the CD/DVD burner if necessary, but it's not really "mission
critical" enough to warrant bringing in the additional KDE backend
required to support it (if the permissions need to be changed, I can do
it myself in 15 seconds, I don't need a GUI from a DE that I don't even
use just to do that).

But you can see from the dependency list that in order to install K3b, I
must install kde-env, kdebase, kdelibs, and kdesu; those are /hard/
dependencies, requried by the application in order for it to run at all;
the applications/libraries installed by the *USE* flags noted are optional:

Runtime Dependencies
k3b-0.12.9

|    >= app-cdr/cdrdao - 1.1.7-r3
    kde-base/kde-env3
    kde-base/kdebase
|    >= kde-base/kdelibs - 3.3
    kde-base/kdesu
    media-libs/libsamplerate
    media-libs/taglib
 |   >= media-sound/cdparanoia - 3.9.8
    media-sound/normalize
    = x11-libs/qt - 3.3*
    *css* media-libs/libdvdcss
    *encode* media-sound/lame
    *encode* media-sound/sox
    *ffmpeg* media-video/ffmpeg
    *flac* media-libs/flac
    *hal* sys-apps/dbus
    *mp3* media-libs/libmad
    *musepack* media-libs/libmpcdec
    *musicbrainz* media-libs/musicbrainz
    *sndfile* media-libs/libsndfile
    *vcd* media-video/vcdimager
    *vorbis* media-libs/libvorbis
    virtual/cdrtools
    *alsa* media-libs/alsalib
    *dvdr* app-cdr/dvd+rwtools

So the necessary KDE backend for the program to run is installed, just
not any "extras" that I don't necessarily want to use. That's what USE
flags do.

>
> I use KDE for my desktop.  I plan to have OOc installed along with
> java and that sort of thing.  I don't have any database software
> installed, that I know of anyway.   I want to make this a reasonable
> install this time.  I have a lot of gnome stuff installed right now
> and I don't use gnome at all.

So, add "-gnome" to your global USE flags-- oh, I see you already do--
and then do an emerge -uaDNtv world (to recompile all apps compiled with
"gnome" support without it), and then an emerge depclean -p  and then an
emerge depclean (or unmerge various packages individually) to remove the
now-unnecessary GNOME libs that were previously installed. You might
also want to disable "gtk", and "gtk2".

When you say you "have a lot of gnome stuff installed", what precisely
do you mean, anyway? You seem to have -gnome in your USE flags, so it's
not as if  you have applications installing unnecessary (for you) GNOME
libs and such. And surely you did not explicitly install GNOME-- or did
you? If so, unmerge it (if you emerged gnome or gnome-light, this will
only unmerge the meta packages, not the applications installed by the
meta packages), and then do an emerge depclean -p (and then an emerge
depclean, or unmerge the packages individually) to remove the
now-orphaned GNOME dependencies.

But you may have a number of packages that depend natively on GNOME/GTK
libs; and if so, then you're just stuck with those, in the same way I'm
stuck with kdebase and qt if I want to use K3b. If that's a real problem
for you, investigate what programs those may be and see if you can find
a KDE or generic X-based alternative (for example, if you use gcolor2, a
GTK/GNOME color-chooser, you may want to switch to kcoloredit, the KDE
color chooser).


> This is my current USE line:
>
>> USE="acl acpi alsa amd arts artsd artswrappersuid -bonobo cdr
>> chroot clanJavaScript -crypt dbus doc -eds ethereal f-prot fdftk
>> gaim gcj gimpprint gkrellm -gnome gphoto2 gtk -gtkhtml hal hbci
>> hpijs gif innodb java javascript jbig justify kde mmx mozdomi
>> mozilla nsplugin ofx offensive openoffice -oss parse-clocks ppds
>> pysol scanner scribus sse tcltk tiff tkinter truetype tuxracer udev
>>  usb X xml xprint yahoo 3dnow "

This means nothing to me, since I have no idea what your system does or
what you do with it.

Do you need optional "java" and "javascript" support globally, for
example? Do you develop java or javascript? Maybe you do; I don't know--
at least then having the "gcj" USE flag enabled would make sense (since
"gcj" is the gcc support for a java compiler, afaik).

Myself, I don't, so I disabled that globally, and only enabled it in
/etc/portage/package.use for those programs I know I want java and
javascript support for (firefox, basically).

Do you do desktop publishing? Do you even use scribus? Do all
applications you may or may not have installed that *can* use Scribus
actually *need* to have *optional* "scribus" support enabled?

And if you don't use a database, why do you have the innodb USE flag
enabled?

USE flags customize your system to your personal needs, and I cannot
know your personal needs-- only you can.

So I would suggest reading through /usr/portage/profiles/use.desc and
/usr/portage/profiles/use.local.desc to understand what the USE flags
you have enabled actually do. Myself, I have an alias in ~/.bashrc,
"stolen" from this list, to quickly scan USE flag definitions:

alias useflag="grep /usr/portage/profiles/use.*desc -e"

So if I do an emerge -uaDNtv world and see a USE flag I don't
understand, I can just do a
(taken from the k3b USE flags above):

 useflag sndfile
/usr/portage/profiles/use.desc:sndfile - Adds support for libsndfile

and make my own decision about whether I want libsndfile support enabled
or not.

I've gotta say, that when I install Gentoo, the longest part of the
installation for me is in fact not the kernel compilation (that's the
second longest), but the scanning of the USE flags and reading of the
notes, to make sure I disable what I don't want and enable what I do. I
could, of course, just leave everything be, and then fix it all later as
you are now doing (that's easy enough), but I'm a recovering
perfectionist as well, so I like to take the time and get it closer to
right the first time.

My USE flags are pretty generic

USE="-kde -arts -eds -esd 16bit 3dnow acpi -apm audiofile -berkdb
bigger-fonts caps cddb dbus dga dv dvd fbcon firefox font-server
gimpprint glut gtkhtml gnutls hal iconv inkjar -ipv6 jack jikes
kdeenablefinal kdexdeltas lcms libcaca maildir mmx mng -mozilla mpi nfs
nptl offensive openexr -pam pic portaudio povray sndfile socks5 sqlite
sse -sse2 svg threads toolbar unicode v4l wmf xprint xvid yv12"

but my /etc/portage/package.use is 115 lines.

I'm happy with that because even looking at it now, I can see that my
global USE flags really */are/* global, enabling support for things I
don't want to have to worry about (I want everything that could have
unicode support to actually have it enabled without me worrying about
it) and disabling support for things I know I don't want (if any package
I may choose to compile could have KDE
support, I know I don't want it, without having to worry about it, and I
don't think I even have ipv6, so I know I don't want that), and
so I know the reason that my package.use is so long is because it
enables/disables *specific* options in *specific* applications, which is
what it's supposed to do.

Such as

media-video/ffmpeg -mmx

Globally, I want mmx support, but ffmpeg won't compile on my system if
such support is enabled, so the support is disabled for that particular
program.

On the other hand, "extra" documentation support (the "doc" USE flag) is
usually disabled by default if it appears at all, but I've enabled it
for imagemagick:

media-gfx/imagemagick doc

because I consider imagemagick complex enough that I want to have the
docs available (because I will surely need them).

I use Samba, but I don't necessarily want everything that can have Samba
support to have Samba support, so for certain packages, "samba" is
specifically enabled in package.use, but not globally.

That's the way it's supposed to work, afaik. It does mean you have to
buckle down and think about what you specifically want/need, but
"customization" always requires that, whether it's because you're
detailing your hotrod (I've clearly seen too much "American Chopper",
"Pimp My Ride" and "Wheeler Dealers" this week, damn boyfriend, damn
Discovery and MTV) or because you're fine-tuning Gentoo.

HTH,
Holly
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