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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
4<!-- The content of this document is licensed under the CC-BY-SA license --> 4<!-- The content of this document is licensed under the CC-BY-SA license -->
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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 1.45 2007/02/20 22:07:04 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>1.36</version>
17<date>2007-02-20</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>
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> 48</subsection>
40<subsection> 49<subsection>
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> 100</p>
103 101
104<p> 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>
123<p> 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 2004.3 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
141<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile">
142<comment>(This example is the sum of the settings in base, default-linux,
143 default-linux/x86 and default-linux/x86/2004.3)</comment>
144USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77
145 foomaticdb gdbm gif gpm gtk imlib jpeg kde gnome libg++ libwww mad
146 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt
136 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 147 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
137</pre> 148</pre>
138 149
139<p> 150<p>
140As you can see, this variable already contains quite a lot of keywords. Do 151As 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 152<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 153the <c>USE</c> variable to your needs: changes in this file will be undone when
143you update Portage! 154you update Portage!
144</p> 155</p>
145 156
146<p> 157<p>
155For instance, to remove support for KDE and QT but add support for ldap, the 166For 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>: 167following <c>USE</c> can be defined in <path>/etc/make.conf</path>:
157</p> 168</p>
158 169
159<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
160USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
161</pre> 172</pre>
162 173
163</body> 174</body>
164</subsection> 175</subsection>
165<subsection> 176<subsection>
205update) your changes will be lost! 216update) your changes will be lost!
206</p> 217</p>
207 218
208<p> 219<p>
209As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE-setting
210during the installation of mozilla. 221during the installation of seamonkey.
211</p> 222</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>
217 223
218<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
219# <i>USE="-java" emerge mozilla</i> 225# <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> 226</pre>
242 227
243</body> 228</body>
244</subsection> 229</subsection>
245<subsection> 230<subsection>
246<title>Precedence</title> 231<title>Precedence</title>
247<body> 232<body>
248 233
249<p> 234<p>
250Of course there is a certain precedence on what setting has priority over the 235Of 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 236USE 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 237<c>java</c> is still used due to a setting that has a higher priority.
238The precedence for the USE setting is, ordered
253by priority (first has lowest priority): 239by priority (first has lowest priority):
254</p> 240</p>
255 241
256<ol> 242<ol>
257 <li> 243 <li>
258 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 244 Default USE setting declared in the <path>make.defaults</path> files part of
259 </li> 245 your profile
260 <li>
261 Inherited USE setting if a package from
262 <path>/etc/make.profile/use.defaults</path> is installed
263 </li> 246 </li>
264 <li> 247 <li>
265 User-defined USE setting in <path>/etc/make.conf</path> 248 User-defined USE setting in <path>/etc/make.conf</path>
266 </li> 249 </li>
267 <li> 250 <li>
271 User-defined USE setting as environment variable 254 User-defined USE setting as environment variable
272 </li> 255 </li>
273</ol> 256</ol>
274 257
275<p> 258<p>
276To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 259To 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 260--info</c>. This will list all relevant variables (including the <c>USE</c>
278the content used by Portage. 261variable) with the content used by Portage.
279</p> 262</p>
280 263
281<pre caption="Running emerge info"> 264<pre caption="Running emerge --info">
282# <i>emerge info</i> 265# <i>emerge --info</i>
283</pre> 266</pre>
284 267
285</body> 268</body>
286</subsection> 269</subsection>
287<subsection> 270<subsection>
288<title>Adapting your Entire System to New USE Flags</title> 271<title>Adapting your Entire System to New USE Flags</title>
289<body> 272<body>
290 273
291<p> 274<p>
292If you have altered your USE flags and you wish to update your entire system to 275If 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. 276use 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> 277</p>
301 278
302<pre caption="Rebuilding your entire system"> 279<pre caption="Rebuilding your entire system">
303# <i>emerge --emptytree world</i> 280# <i>emerge --update --deep --newuse world</i>
304</pre> 281</pre>
305 282
306<p> 283<p>
307Next, run Portage's depclean to remove the conditional dependencies that 284Next, 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 285were emerged on your "old" system but that have been obsoleted by the new USE
309flags. 286flags.
310</p> 287</p>
311 288
312<warn> 289<warn>
313Running <c>emerge depclean</c> is a dangerous operation and should be handled 290Running <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 291with 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 292it 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. 293<c>-p</c> switch to have depclean only list the packages without removing them.
317</warn> 294</warn>
318 295
319<pre caption="Removing obsoleted packages"> 296<pre caption="Removing obsoleted packages">
320# <i>emerge -p depclean</i> 297# <i>emerge -p --depclean</i>
321</pre> 298</pre>
322 299
300<p>
301When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
302applications that are dynamically linked against shared objects provided by
303possibly removed packages. <c>revdep-rebuild</c> is part of the
304<c>gentoolkit</c> package; don't forget to emerge it first.
323<p> 305</p>
306
307<pre caption="Running revdep-rebuild">
308# <i>revdep-rebuild</i>
309</pre>
310
311<p>
324When depclean has finished, your system is using the new USE flag settings. 312When all this is accomplished, your system is using the new USE flag settings.
325</p> 313</p>
326 314
327</body> 315</body>
328</subsection> 316</subsection>
329</section> 317</section>
332<subsection> 320<subsection>
333<title>Viewing available USE-flags</title> 321<title>Viewing available USE-flags</title>
334<body> 322<body>
335 323
336<p> 324<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>
342
343<p>
344Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 325Let 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 326find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
346anything) and <c>--verbose</c> (give more output) options: 327options:
347</p> 328</p>
348 329
349<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE-flags">
350# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
351These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
352 333
353Calculating dependencies ...done! 334Calculating dependencies ...done!
354[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 335[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
355+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
356-moznocompose -moznoxft 337-moznoroaming -postgres -xinerama -xprint" 0 kB
357</pre> 338</pre>
358 339
359<p> 340<p>
360<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 341<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 342dedicated to package information called <c>equery</c> which resides in the
362<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 343<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
363</p> 344</p>
364 345
365<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
366# <i>emerge --usepkg gentoolkit</i> 347# <i>emerge gentoolkit</i>
367</pre> 348</pre>
368 349
369<p> 350<p>
370Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 351Now 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: 352certain package. For instance, for the <c>gnumeric</c> package:
372</p> 353</p>
373 354
374<pre caption="Using etcat to view used USE-flags"> 355<pre caption="Using equery to view used USE-flags">
375# <i>etcat uses gnumeric</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ]
376[ Colour Code : <i>set</i> <comment>unset</comment> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
377[ Legend : (U) Col 1 - Current USE flags ] 359[ Legend : Left column (U) - USE flags from make.conf ]
378[ : (I) Col 2 - Installed With USE flags ] 360[ : Right column (I) - USE flags packages was installed with ]
379
380 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 361[ Found these USE variables for app-office/gnumeric-1.6.3 ]
381 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 362 U I
382 - - <comment>gnomedb</comment> : unknown 363- - <i>debug</i> : Tells configure and the makefiles to build for debugging.
364 Effects vary across packages, but generally it will at
365 least add -g to CFLAGS. Remember to set FEATURES=nostrip too
366- - <i>gnome</i> : Adds GNOME support
383 + + <i>python</i> : Adds support/bindings for the Python language 367+ + <comment>python</comment> : Adds support/bindings for the Python language
384 + + <i>bonobo</i> : Adds support for gnome-base/bonobo (Gnome CORBA interfaces) 368- - <i>static</i> : !!do not set this during bootstrap!! Causes binaries to be
369 statically linked instead of dynamically
385</pre> 370</pre>
386 371
387</body> 372</body>
388</subsection> 373</subsection>
389</section> 374</section>

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