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1<?xml version='1.0' encoding='UTF-8'?> 1<?xml version='1.0' encoding='UTF-8'?>
2<!DOCTYPE sections SYSTEM "/dtd/book.dtd"> 2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3 3
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6 6
7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.20 2004/10/10 11:09:27 swift Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.50 2010/06/07 09:20:00 nightmorph Exp $ -->
8 8
9<sections> 9<sections>
10
11<abstract>
12USE flags are a very important aspect of Gentoo. In this chapter, you learn to
13work with USE flags and understand how USE flags interact with your system.
14</abstract>
15
16<version>1.39</version>
17<date>2010-06-07</date>
18
10<section> 19<section>
11<title>What are USE-flags?</title> 20<title>What are USE flags?</title>
12<subsection> 21<subsection>
13<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE flags</title>
14<body> 23<body>
15 24
16<p> 25<p>
17When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
18system for that matter) you make choices depending on the environment you are 27system for that matter) you make choices depending on the environment you are
23<p> 32<p>
24This is not only true for choosing what packages you want to install, but also 33This is not only true for choosing what packages you want to install, but also
25what features a certain package should support. If you don't need OpenGL, why 34what features a certain package should support. If you don't need OpenGL, why
26would you bother installing OpenGL and build OpenGL support in most of your 35would you bother installing OpenGL and build OpenGL support in most of your
27packages? If you don't want to use KDE, why would you bother compiling packages 36packages? If you don't want to use KDE, why would you bother compiling packages
28with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
29</p> 38</p>
30 39
31<p> 40<p>
32To help users in deciding what to install/activate and what not, we wanted the 41To help users in deciding what to install/activate and what not, we wanted the
33user to specify his/her environment in an easy way. This forces the user into 42user to specify his/her environment in an easy way. This forces the user into
34deciding what they really want and eases the process for Portage, our package 43deciding what they really want and eases the process for Portage, our package
35managment system, to make useful decisions. 44management system, to make useful decisions.
36</p> 45</p>
37 46
38</body> 47</body>
39</subsection>
40<subsection> 48</subsection>
49<subsection>
41<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
42<body> 51<body>
43 52
44<p> 53<p>
45Enter the USE-flags. Such a flag is a keyword that embodies support and 54Enter the USE flags. Such a flag is a keyword that embodies support and
46dependency-information for a certain concept. If you define a certain USE-flag, 55dependency-information for a certain concept. If you define a certain USE flag,
47Portage will know that you want support for the chosen keyword. Of course 56Portage will know that you want support for the chosen keyword. Of course
48this also alters the dependency information for a package. 57this also alters the dependency information for a package.
49</p> 58</p>
50 59
51<p> 60<p>
64</p> 73</p>
65 74
66</body> 75</body>
67</subsection> 76</subsection>
68<subsection> 77<subsection>
69<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
70<body> 79<body>
71 80
72<p> 81<p>
73There are two types of USE-flags: <e>global</e> and <e>local</e> USE-flags. 82There are two types of USE flags: <e>global</e> and <e>local</e> USE flags.
74</p> 83</p>
75 84
76<ul> 85<ul>
77 <li> 86 <li>
78 A <e>global</e> USE-flag is used by several packages, system-wide. This is 87 A <e>global</e> USE flag is used by several packages, system-wide. This is
79 what most people see as USE-flags. 88 what most people see as USE flags.
80 </li>
81 <li> 89 </li>
90 <li>
82 A <e>local</e> USE-flag is used by a single package to make package-specific 91 A <e>local</e> USE flag is used by a single package to make package-specific
83 decisions. 92 decisions.
84 </li> 93 </li>
85</ul> 94</ul>
86 95
87<p> 96<p>
88A list of available global USE-flags can be found <uri 97A list of available global USE flags can be found <uri
89link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml">online</uri> or locally in
90<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 99<path>/usr/portage/profiles/use.desc</path>.
91snippet:
92</p>
93
94<pre caption="A short snippet of available USE-flags">
95gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
96gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
97gtkhtml - Adds support for gnome-extra/gtkhtml
98guile - Adds support for dev-util/guile (interpreter for Scheme)
99icc - Use the Intel C++ Compiler if the package supports it
100icc-pgo - Enable PGO data generation or use when use icc.
101imap - Adds support for IMAP
102</pre>
103
104<p> 100</p>
101
102<p>
105A list of available local USE-flags can be found locally in 103A list of available local USE flags can be found locally in
106<path>/usr/portage/profiles/use.local.desc</path>. 104<path>/usr/portage/profiles/use.local.desc</path>.
107</p> 105</p>
108 106
109</body> 107</body>
110</subsection> 108</subsection>
111</section> 109</section>
112<section> 110<section>
113<title>Using USE-flags</title> 111<title>Using USE flags</title>
114<subsection> 112<subsection>
115<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
116<body> 114<body>
117 115
118<p> 116<p>
119In the hope you are convinced of the importance of USE-flags we will now inform 117In the hope you are convinced of the importance of USE flags we will now inform
120you how to declare USE-flags. 118you how to declare USE flags.
121</p>
122
123<p> 119</p>
120
121<p>
124As previously mentioned, all USE-flags are declared inside the <c>USE</c> 122As previously mentioned, all USE flags are declared inside the <c>USE</c>
125variable. To make it easy for users to search and pick USE-flags, we already 123variable. To make it easy for users to search and pick USE flags, we already
126provide a <e>default</e> USE setting. This setting is a collection of USE-flags 124provide a <e>default</e> USE setting. This setting is a collection of USE flags
127we think are commonly used by the Gentoo users. This default setting is declared 125we think are commonly used by the Gentoo users. This default setting is declared
128in the <path>/etc/make.profile/make.defaults</path> file. Let us take a look at 126in the <path>make.defaults</path> files part of your profile.
129this default setting: 127</p>
128
130</p> 129<p>
130The profile your system listens to is pointed to by the
131<path>/etc/make.profile</path> symlink. Each profile works on top of another,
132larger profile, the end result is therefore the sum of all profiles. The top
133profile is the <path>base</path> profile
134(<path>/usr/portage/profiles/base</path>).
135</p>
131 136
132<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 137<p>
133USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 138Let us take a look at this default setting for the 10.0 profile:
134 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 139</p>
135 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 140
136 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 141<pre caption="Cumulative make.defaults USE variable for the 10.0 profile">
142<comment>(This example is the sum of the settings in base, default/linux,
143 default/linux/x86 and default/linux/x86/10.0/)</comment>
144USE="a52 aac acpi alsa branding cairo cdr dbus dts dvd dvdr emboss encode exif
145fam firefox flac gif gpm gtk hal jpeg lcms ldap libnotify mad mikmod mng mp3
146mp4 mpeg ogg opengl pango pdf png ppds qt3support qt4 sdl spell
147startup-notification svg tiff truetype vorbis unicode usb X xcb x264 xml
148xulrunner xv xvid"
137</pre> 149</pre>
138 150
139<p> 151<p>
140As you can see, this variable already contains quite a lot of keywords. Do 152As you can see, this variable already contains quite a lot of keywords. Do
141<b>not</b> alter the <path>/etc/make.profile/make.defaults</path> file to tailor 153<b>not</b> alter any <path>make.defaults</path> file to tailor
142the <c>USE</c> variable to your needs: changes in this file will be undone when 154the <c>USE</c> variable to your needs: changes in this file will be undone when
143you update Portage! 155you update Portage!
144</p> 156</p>
145 157
146<p> 158<p>
147To change this default setting, you need to add or remove keywords to the 159To change this default setting, you need to add or remove keywords to the
148<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable 160<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable
149in <path>/etc/make.conf</path>. In this variable you add the extra USE-flags you 161in <path>/etc/make.conf</path>. In this variable you add the extra USE flags you
150require, or remove the USE-flags you don't want. This latter is done by 162require, or remove the USE flags you don't want. This latter is done by
151prefixing the keyword with the minus-sign ("-"). 163prefixing the keyword with the minus-sign ("-").
152</p> 164</p>
153 165
154<p> 166<p>
155For instance, to remove support for KDE and QT but add support for ldap, the 167For instance, to remove support for KDE and QT but add support for ldap, the
156following <c>USE</c> can be defined in <path>/etc/make.conf</path>: 168following <c>USE</c> can be defined in <path>/etc/make.conf</path>:
157</p> 169</p>
158 170
159<pre caption="An example USE setting in /etc/make.conf"> 171<pre caption="An example USE setting in /etc/make.conf">
160USE="-kde -qt ldap" 172USE="-kde -qt4 ldap"
161</pre> 173</pre>
162 174
163</body> 175</body>
164</subsection> 176</subsection>
165<subsection> 177<subsection>
168 180
169<p> 181<p>
170Sometimes you want to declare a certain USE flag for one (or a couple) of 182Sometimes you want to declare a certain USE flag for one (or a couple) of
171applications but not system-wide. To accomplish this, you will need to create 183applications but not system-wide. To accomplish this, you will need to create
172the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit 184the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
173<path>/etc/portage/package.use</path>. 185<path>/etc/portage/package.use</path>. This is usually a single file, but can
186also be a directory; see <c>man portage</c> for more information. The following
187examples assume <path>package.use</path> is a single file.
174</p> 188</p>
175 189
176<p> 190<p>
177For instance, if you don't want <c>berkdb</c> support globally but you do want 191For instance, if you don't want <c>berkdb</c> support globally but you do want
178it for <c>mysql</c>, you would add: 192it for <c>mysql</c>, you would add:
192</pre> 206</pre>
193 207
194</body> 208</body>
195</subsection> 209</subsection>
196<subsection> 210<subsection>
197<title>Declare temporary USE-flags</title> 211<title>Declare temporary USE flags</title>
198<body> 212<body>
199 213
200<p> 214<p>
201Sometimes you want to set a certain USE-setting only once. Instead of editing 215Sometimes you want to set a certain USE setting only once. Instead of editing
202<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 216<path>/etc/make.conf</path> twice (to do and undo the USE changes) you can just
203declare the USE-variable as environment variable. Remember that, when you 217declare the USE variable as environment variable. Remember that, when you
204re-emerge or update this application (either explicitly or as part of a system 218re-emerge or update this application (either explicitly or as part of a system
205update) your changes will be lost! 219update) your changes will be lost!
206</p> 220</p>
207 221
208<p> 222<p>
209As an example we will temporarily remove java from the USE-setting 223As an example we will temporarily remove java from the USE setting
210during the installation of mozilla. 224during the installation of seamonkey.
211</p> 225</p>
212
213<note>
214The <c>emerge</c> command will be discussed more thoroughly in <uri
215link="?part=2&amp;chap=2">Portage and Software</uri>.
216</note>
217 226
218<pre caption="Using USE as environment variable"> 227<pre caption="Using USE as environment variable">
219# <i>USE="-java" emerge mozilla</i> 228# <i>USE="-java" emerge seamonkey</i>
220</pre>
221
222</body>
223</subsection>
224<subsection>
225<title>Inheriting USE-flags</title>
226<body>
227
228<p>
229Some packages don't only listen to USE-flags, but also provide USE-flags. When
230you install such a package, the USE-flag they provide is added to your USE
231setting. To view the list of packages that provide a USE-flag, check
232<path>/etc/make.profile/use.defaults</path>:
233</p>
234
235<pre caption="A snippet from /etc/make.profile/use.defaults">
236gnome gnome-base/gnome
237gtk x11-libs/gtk+
238qt x11-libs/qt
239kde kde-base/kdebase
240motif x11-libs/openmotif
241</pre> 229</pre>
242 230
243</body> 231</body>
244</subsection> 232</subsection>
245<subsection> 233<subsection>
246<title>Precedence</title> 234<title>Precedence</title>
247<body> 235<body>
248 236
249<p> 237<p>
250Of course there is a certain precedence on what setting has priority over the 238Of course there is a certain precedence on what setting has priority over the
251USE setting. You don't want to declare <c>USE="-java"</c> only to see that 239USE setting. You don't want to declare <c>USE="-java"</c> only to see that
252<c>java</c> is declared anyway. The precedence for the USE setting is, ordered 240<c>java</c> is still used due to a setting that has a higher priority.
241The precedence for the USE setting is, ordered
253by priority (first has lowest priority): 242by priority (first has lowest priority):
254</p> 243</p>
255 244
256<ol> 245<ol>
257 <li> 246 <li>
258 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 247 Default USE setting declared in the <path>make.defaults</path> files part of
259 </li> 248 your profile
260 <li>
261 Inherited USE setting if a package from
262 <path>/etc/make.profile/use.defaults</path> is installed
263 </li> 249 </li>
264 <li> 250 <li>
265 User-defined USE setting in <path>/etc/make.conf</path> 251 User-defined USE setting in <path>/etc/make.conf</path>
266 </li> 252 </li>
267 <li> 253 <li>
271 User-defined USE setting as environment variable 257 User-defined USE setting as environment variable
272 </li> 258 </li>
273</ol> 259</ol>
274 260
275<p> 261<p>
276To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 262To view the final <c>USE</c> setting as seen by Portage, run <c>emerge
277This will list all relevant variables (including the <c>USE</c> variable) with 263--info</c>. This will list all relevant variables (including the <c>USE</c>
278the content used by Portage. 264variable) with the content used by Portage.
279</p> 265</p>
280 266
281<pre caption="Running emerge info"> 267<pre caption="Running emerge --info">
282# <i>emerge info</i> 268# <i>emerge --info</i>
283</pre> 269</pre>
284 270
285</body> 271</body>
286</subsection> 272</subsection>
287<subsection> 273<subsection>
288<title>Adapting your Entire System to New USE Flags</title> 274<title>Adapting your Entire System to New USE Flags</title>
289<body> 275<body>
290 276
291<p> 277<p>
292If you have altered your USE flags and you wish to update your entire system to 278If you have altered your USE flags and you wish to update your entire system to
293use the new USE flags, you can try following the next steps to accomplish this. 279use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
294Note however that these steps will take a long time to finish and that work is
295on the way to adjust Portage to handle this behaviour quicker and automatically.
296</p>
297
298<p>
299First of all, rebuild your entire system using the new USE flags:
300</p> 280</p>
301 281
302<pre caption="Rebuilding your entire system"> 282<pre caption="Rebuilding your entire system">
303# <i>emerge --emptytree world</i> 283# <i>emerge --update --deep --newuse world</i>
304</pre> 284</pre>
305 285
306<p> 286<p>
307Next, run Portage's depclean to remove the conditional dependencies that 287Next, run Portage's depclean to remove the conditional dependencies that
308were emerged on your "old" system but that have been obsoleted by the new USE 288were emerged on your "old" system but that have been obsoleted by the new USE
309flags. 289flags.
310</p> 290</p>
311 291
312<warn> 292<warn>
313Running <c>emerge depclean</c> is a dangerous operation and should be handled 293Running <c>emerge --depclean</c> is a dangerous operation and should be handled
314with care. Double-check the provided list of "obsoleted" packages to make sure 294with care. Double-check the provided list of "obsoleted" packages to make sure
315it doesn't remove packages you need. In the following example we add the 295it doesn't remove packages you need. In the following example we add the
316<c>-p</c> switch to have depclean only list the packages without removing them. 296<c>-p</c> switch to have depclean only list the packages without removing them.
317</warn> 297</warn>
318 298
319<pre caption="Removing obsoleted packages"> 299<pre caption="Removing obsoleted packages">
320# <i>emerge -p depclean</i> 300# <i>emerge -p --depclean</i>
321</pre> 301</pre>
322 302
303<p>
304When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
305applications that are dynamically linked against shared objects provided by
306possibly removed packages. <c>revdep-rebuild</c> is part of the
307<c>gentoolkit</c> package; don't forget to emerge it first.
323<p> 308</p>
309
310<pre caption="Running revdep-rebuild">
311# <i>revdep-rebuild</i>
312</pre>
313
314<p>
324When depclean has finished, your system is using the new USE flag settings. 315When all this is accomplished, your system is using the new USE flag settings.
325</p> 316</p>
326 317
327</body> 318</body>
328</subsection> 319</subsection>
329</section> 320</section>
330<section> 321<section>
331<title>Package specific USE-flags</title> 322<title>Package specific USE flags</title>
332<subsection> 323<subsection>
333<title>Viewing available USE-flags</title> 324<title>Viewing available USE flags</title>
334<body> 325<body>
335 326
336<p>
337In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
338we will explain how to manage your installed software and how to work with
339<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
340you how to view what USE-flags a package uses.
341</p> 327<p>
342
343<p>
344Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 328Let us take the example of <c>seamonkey</c>: what USE flags does it listen to? To
345find out, we use <c>emerge</c> with the <c>--pretend</c> (don't really do 329find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
346anything) and <c>--verbose</c> (give more output) options: 330options:
347</p> 331</p>
348 332
349<pre caption="Viewing the used USE-flags"> 333<pre caption="Viewing the used USE flags">
350# <i>emerge --pretend --verbose mozilla</i> 334# <i>emerge --pretend --verbose seamonkey</i>
351These are the packages that I would merge, in order: 335These are the packages that I would merge, in order:
352 336
353Calculating dependencies ...done! 337Calculating dependencies ...done!
354[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 338[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
355+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 339-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
356-moznocompose -moznoxft 340-moznoroaming -postgres -xinerama -xprint" 0 kB
357</pre> 341</pre>
358 342
359<p> 343<p>
360<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 344<c>emerge</c> isn't the only tool for this job. In fact, we have a tool
361dedicated to package information called <c>etcat</c> which resides in the 345dedicated to package information called <c>equery</c> which resides in the
362<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 346<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
363</p> 347</p>
364 348
365<pre caption="Installing gentoolkit"> 349<pre caption="Installing gentoolkit">
366# <i>emerge --usepkg gentoolkit</i> 350# <i>emerge gentoolkit</i>
367</pre> 351</pre>
368 352
369<p> 353<p>
370Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 354Now run <c>equery</c> with the <c>uses</c> argument to view the USE flags of a
371certain package. For instance, for the <c>gnumeric</c> package: 355certain package. For instance, for the <c>gnumeric</c> package:
372</p> 356</p>
373 357
374<pre caption="Using etcat to view used USE-flags"> 358<pre caption="Using equery to view used USE flags">
375# <i>etcat uses gnumeric</i> 359# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
376[ Colour Code : <i>set</i> <comment>unset</comment> ] 360[ Searching for packages matching =gnumeric-1.6.3... ]
377[ Legend : (U) Col 1 - Current USE flags ] 361[ Colour Code : set unset ]
378[ : (I) Col 2 - Installed With USE flags ] 362[ Legend : Left column (U) - USE flags from make.conf ]
379 363[ : Right column (I) - USE flags packages was installed with ]
380 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 364[ Found these USE variables for app-office/gnumeric-1.6.3 ]
381 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 365 U I
382 - - <comment>gnomedb</comment> : unknown 366 - - debug : Enable extra debug codepaths, like asserts and extra output.
367 If you want to get meaningful backtraces see
368 http://www.gentoo.org/proj/en/qa/backtraces.xml .
369 + + gnome : Adds GNOME support
383 + + <i>python</i> : Adds support/bindings for the Python language 370 + + python : Adds support/bindings for the Python language
384 + + <i>bonobo</i> : Adds support for gnome-base/bonobo (Gnome CORBA interfaces) 371 - - static : !!do not set this during bootstrap!! Causes binaries to be
372 statically linked instead of dynamically
385</pre> 373</pre>
386 374
387</body> 375</body>
388</subsection> 376</subsection>
389</section> 377</section>

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