Newbie needs help (for example USE-flags)

macoute · n00b Joined: 21 Nov 2006 Posts: 1

Hello,

Im just switching to Gentoo from my Debian Unstable. I'm installing with stage3 in chroot environment.

Installation went fine this far, but as I'm now installing KDE and multimedia - full desktop,that is - I could use some help.

What is the basical use of USE-flags? As I'm very unsure about what I'm going to install to this desktop, I don't know whether I should choose some flags or not. Is there any problem with enabling about the all flags? What is the easiest way to accomplish this? If I don't use the flag dvdr for example now, but I install a DVDR-drive at some point, do I need to recompile the whole system? I actually know only a bit about this emerge although I read the documentation in gentoo install documents, so where could I find some extra info?

Why does emerge fail very often? Is there something wrong with something I did, cause emerge fails very often, outputting once this, once that. Once, when I emerged multiple programs (kdebase, x11-xorg, amarok, mplayer etc) it compiled for an hour and then complained that I'm not using the X flag, although emerge --info stated otherwise. Now it failed with

!!! Digest verification failed:
!!! /usr/portage/net-libs/libtorrent/ChangeLog
!!! Reason: Failed on MD5 verification
!!! Got: e77641888b16c612a928d4198bf62659
!!! Expected: 3e9cf8da9acd62a663d726101fd9547d
Error in sys.exitfunc:

when emerging rtorrent. How could I check i have made my make.conf a sensible one?

Does emerge reinstall programs I emerge if they have already been installed?

beandog · Posted: Tue Nov 21, 2006 4:31 pm Post subject:

The USE flags just enable certain compile-time options like say ... enable mp3 support or add support for a GUI. Each result depends on what the package enables with those USE flags, which are generalized in nature.

Don't turn all the USE flags on as that would make everything take quite a long time to compile, and youd be needlessly pulling in a lot of dependencies. Just check each package as you go to see which flags they have, then lookup what they do.

You can emerge gentoolkit and run euse -i foo to see what USE flag does.

batistuta · Veteran Joined: 29 Jul 2005 Posts: 1384 Location: Aachen

one useful program for managing your USE flags is called "ufed". It provides some descriptions and automatically updates your make.conf based on the input. The program is in portage.

I also suggest you to choose a profile before you tweak your flags. You probably want desktop profile. But after that, take a look at the default chose USE flags. For instance, the desktop profile chooses both gnome and kde. You probably want to deactivate these.
Use ufed *after* selecting the profile, since ufed removes redundant flags from your make.conf (flags that are in both make.conf and the profile)

My use flags for example are the following (many seem to be missing, because they are in the desktop profile already)

MM23 · Tux's lil' helper Joined: 10 Nov 2006 Posts: 83

For the most part, it's best to put things you absolutely know you'll want programs to use (i.e if you're a perl programmer, why not have everything you install compile with perl scripting support?) in make.conf, and otherwise I just set up specific use flags for each application in package.use. It's a little tedious, but sometimes you just don't need mp3 support or vnc support for EVERY single thing you EVER emerge.

Bones McCracker · Veteran Joined: 14 Mar 2006 Posts: 1611 Location: U.S.A.

Building a set of USE flags is an iterative process as you install packages. You don't need to set them all up at once the day you finish your install; you will be setting them up as you go. Most important, don't just go enable them all like you were asking.

It's also a very user-specific thing. Asking for "example USE flags" is like asking somebody for an "example income tax return" -- theirs has little to do with yours. There is, however, a good process you can follow to build your own set right.

Also, USE flag settings are at the heart of customizing your system, which is what I think Gentoo is all about. So this is an important aspect of Gentoo that you should take the time to learn about and use correctly. Read and re-reach the handbook sections about USE flags. USE flags are something that many users don't do right. The documentation can be somewhat confusing, though, so I'll try to pass on what might be a couple of useful thoughts regarding this.

Some key points:

1. USE flags are set in a couple different configuration files and it's important to understand how they interact. During install you choose a portage profile (by pointing symlink /etc/make.profile at your profile of choice in /usr/portage/profiles). In each portage profile directory, there is a file make.defaults, which comprises a default set of USE flags as well as other portage settings. For you, a good choice would be the "desktop" profile. Picking a profile is the only flexibility you have; it's best not to edit the make.defaults file because it will be changed by updates. Also, some packages will add default USE flags to the file when emerged. So that's your first consideration -- do you have the right profile.

2. These profile defaults are over-ridden by settings that you place in configuration files in the /etc directory. Global settings you put in /etc/make.conf, and package-specific settings you put in a couple files that go in /etc/portage. By definition, these files you DO edit.
For optimal control it's important to differentiate between "Global" and "Local" USE flags and to manage each in the appropriate configuration file. "Global" USE flags are flags you are confident in setting one way for all packages. It is best to use your /etc/make.conf file for global USE flags only, and to place the local USE flags specific to a given package in /etc/portage/package.use. For example, the USE flag "SSL" might tell one package to link to a library that enables it to authenticate with SSL, but it might tell a different package to link to and depend upon an SSL certificate management application and its libraries (thereby creating a whole new dependency for an application you had not planned to install on your system and have no use for, which itself carries its own set of dependencies). So I make sure I understand what each USE flag means to each ebuild before I emerge it, and I am careful to put the right USE flags in make.conf vs. package.use.

3. USE flags aren't something you set up and then forget. You should be checking the USE flags of each package you emerge and possibly modifying one or more of the aforementioned configuration files. It's a process. A good way to do this is

RedEagle · n00b Joined: 07 Feb 2007 Posts: 3

Hey everyone. As apparent from the thread subject, this is my first post here on Gentoo forums. Just a quick question about USE flags:

As this is my first Gentoo install I am following the handbook pretty much word for word, nervous that if I deviate I might mess something up. Anyway I reached the part that describes setting your USE flags in /etc/make.conf. It talks about how Gentoo compiles software from source, removing and adding this according to your USE flags. I was just wondering if I'm not exactly sure what I will be setting up this system for (KDE, GNOME, etc) would it work to not specify any USE flags at the moment. Basically I am just worried that I will remove something I want later on and then be forced to recompile my entire system.

Thanks for the help you guys, and great forums BTW.
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Phenax · l33t Joined: 10 Mar 2006 Posts: 972

No, this will not harm you at all, besides the possibility of recompiling just a few programs. Heck, you could use both USE flags! USE flags are for optional support in programs. If a program needs something, it will grab it. You can get KDE or Gnome or any of their programs using the package manager at any time, regardless of your USE flags.
Say the IRC client, kvirc has optional KDE support (It does..). If you enable the KDE useflag, then it will be compiled with a nice KDE interface -- it will also drag in the required kde packages. With the -kde use flag, it will just use the default X interface and not drag in the kde packages. Look below and you can update programs to your currently set USE flags.

Anyways, the only things you'd need to recompile are the applications that use the KDE useflag, which are few -- that's because if an application REQUIRES KDE, it will get it. Not too many applications have just optional KDE support

You can update your whole system to your current set of USE flags later by doing a

RedEagle · n00b Joined: 07 Feb 2007 Posts: 3

Thanks very much, I think I'll just go with the USE flags recommended in the handbook:

Phenax · l33t Joined: 10 Mar 2006 Posts: 972

Yes, that would be good for a kde-based system. As I said, it only enables optional dependencies and features. If a package needs something, it will always get it. Though, it is in good practice to make your USE flags reflect what you will be doing, because if you compile Firefox with Gnome support, it will of course be better integrated with Gnome! It's also in good practice to always try to

RedEagle · n00b Joined: 07 Feb 2007 Posts: 3

I'll be sure to check that out when I get the system up and running (hopefully it won't be too much longer

-- I'm about to configure the kernel ).

EDIT (didn't see bit about IRC): Joining up now; I'll probably need help configuring the kernel :oops:

. I appreciate all of your help.
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Dikkiedik · Guru Joined: 04 Oct 2004 Posts: 406 Location: Netherlands

CNLiberal · Posted: Thu Mar 08, 2007 10:20 pm Post subject: What USE flags do I need?

I'm not very well versed at Gentoo. However, I think it's probably the easiest to upgrade to new versions. With Fedora, you have the problem that the RPMs only work for certain versions. I just want to have a machine that will upgrade without having to re-install the OS. Maybe this can be done easily on Fedora, I don't know. What I want is to rebuild my FC4 backend server to a Gentoo system. When I say backend, I'm running MythTV at home and this machine is my master backend server. I'd like to load MythTV v.19 so i don't have to reload my frontend. So basically, I don't know USE flags at all. I want to run MythTV, IVTV, Xine (w DVD reading/writing support), sharing folders as samba (i could try CIFS but I'm not sure how well it's supported on my frontend), exporting NFS directories, KDE, MySQL (something in the version 4 range), nvidia grafx (with XGL possibly), LVM2, Alsa sound (analog out, with the option of digital out), firefox, gaim, amarok, and open office. I'm sure there's other things I want, but I just want to know what USE flags I'll need to get this started? I'm sure I can research the rest, but I've always found USE flags to be difficult. I don't want to emerge KDE and then find out I forgot NFS and SAMBA support. Thanks for your patience with the n00b!

Jim
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likewhoa · Posted: Thu Mar 08, 2007 10:27 pm Post subject:

read this USE flag description page..

http://www.gentoo.org/dyn/use-index.xml

if you want to read descriptions on USE flags from the command line,..

CNLiberal · Posted: Thu Mar 08, 2007 10:41 pm Post subject:

I've read those and I'm still at a loss. I guess I can try again. I wanted to try this this weekend, but I guess I'll have to wait. i still need to copy all the data off my LVM partition. I'll have to bring it in to work because I have access to terabyte servers.
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thorpe · Posted: Fri Mar 09, 2007 3:48 am Post subject:

As an example, before you emerge anything use the -pv switch, this will enlighten you as to which flags you may, may not whish to enable.
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likewhoa · Posted: Fri Mar 09, 2007 4:39 am Post subject:

to add to the above post,.. when you find certain use flags you want to use with a certain package, but wish to only use them for that package only instead of globally just make an entry to /etc/portage/package.use

example, to add java support for mozilla-firefox only and not globally you would..

tuam · l33t Joined: 04 May 2004 Posts: 765 Location: CGN, Germany

wolf31o2 · Posted: Fri Mar 09, 2007 5:48 pm Post subject:

I would suggest you start with using the "desktop" subprofile for your architecture. I'm assuming here that you're using x86, based on your sig. I would use the default-linux/x86/2006.1/desktop profile, as it will enable many of the most useful options for a desktop system. You can negate USE flags you don't want in make.conf, so if you don't want GNOME, you would have the following in make.conf:

USE="-esd -gnome"

The simplest thing to do is to not touch anything and just use the defaults. Over time, you'll start to figure out exactly what different USE flags do. Also, as mentioned already, use of "emerge -vp packagename" will show you the USE flags affecting the merge.
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shooter · n00b Joined: 09 Mar 2007 Posts: 1

I followed the Gentoo Installation Guide, and I use the USE flag in the documentation.But I met some problems.

So you should read the feedback on the screen, and use THAT USE flag.

vorobei99 · n00b Joined: 11 Aug 2007 Posts: 12

What flags i need to use to have good workstation to support all futuries like dvd/cd rw , compision , beryl , opengl ..etc

Please make me advice..I am newbie.Last time i forget to use sound options .PLease help

didymos · Posted: Mon Aug 20, 2007 1:49 pm Post subject:

Just use the desktop profile to get the most commonly used/needed flags. For any others, you just need to look through them, see what they're for, and decide whether or not you want support for the things they enable. Most are pretty self-explanatory.
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der.gecko · Posted: Mon Aug 20, 2007 2:39 pm Post subject:

additionally, try common sense!

here is a list of available use flags:

http://www.gentoo.org/dyn/use-index.xml#doc_chap1

general rule... if you don't know what a specific use flag does, you probably won't need it^^

nixnut · Posted: Mon Aug 20, 2007 5:12 pm Post subject:

merged above three posts here
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Spudgun · n00b Joined: 26 Oct 2007 Posts: 30

Hey everyone,
I've just finished installing Gentoo, and would now like to know some USE flags which people would recommend for a Gnome desktop workstation (DVD Watching, CD writing, graphics editing, document writing, web browsing, etc), without any KDE parts what so ever?

Thanks alot,
Spudgun

Ehnvis · Guru Joined: 13 Jun 2006 Posts: 305 Location: /dev/random

Start out with using the 2007.0 desktop profile. If thats not enough you can add USE flags to /etc/make.conf.

eselect profile list to show the available profiles, the one marked with a star is the one you use. If your not using the 2007.0 desktop profile change with eselect profile set <number of 2007.0 desktop profile>. Then run an emerge -uDN world to update your system to use the new use flags.

If you dont have the eselect command emerge gentoolkit.
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