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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 -->
5<!-- See http://creativecommons.org/licenses/by-sa/1.0 --> 5<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
6 6
7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.24 2004/11/20 22:23:30 neysx 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 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
11<version>1.21</version> 16<version>1.36</version>
12<date>2004-10-21</date> 17<date>2007-02-20</date>
13 18
14<section> 19<section>
15<title>What are USE-flags?</title> 20<title>What are USE-flags?</title>
16<subsection> 21<subsection>
17<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE-flags</title>
34 39
35<p> 40<p>
36To 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
37user 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
38deciding 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
39managment system, to make useful decisions. 44management system, to make useful decisions.
40</p> 45</p>
41 46
42</body> 47</body>
43</subsection> 48</subsection>
44<subsection> 49<subsection>
89</ul> 94</ul>
90 95
91<p> 96<p>
92A list of available global USE-flags can be found <uri 97A list of available global USE-flags can be found <uri
93link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml">online</uri> or locally in
94<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 99<path>/usr/portage/profiles/use.desc</path>.
95snippet:
96</p>
97
98<pre caption="A short snippet of available USE-flags">
99gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
100gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
101gtkhtml - Adds support for gnome-extra/gtkhtml
102guile - Adds support for dev-util/guile (interpreter for Scheme)
103icc - Use the Intel C++ Compiler if the package supports it
104icc-pgo - Enable PGO data generation or use when use icc.
105imap - Adds support for IMAP
106</pre> 100</p>
107 101
108<p> 102<p>
109A list of available local USE-flags can be found locally in 103A list of available local USE-flags can be found locally in
110<path>/usr/portage/profiles/use.local.desc</path>. 104<path>/usr/portage/profiles/use.local.desc</path>.
111</p> 105</p>
127<p> 121<p>
128As 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>
129variable. 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
130provide 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
131we 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
132in 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.
133this default setting: 127</p>
128
134</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>
135 136
136<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 137<p>
137USE="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:
138 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 139</p>
139 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
140 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"
141</pre> 148</pre>
142 149
143<p> 150<p>
144As 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
145<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
146the <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
147you update Portage! 154you update Portage!
148</p> 155</p>
149 156
150<p> 157<p>
159For 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
160following <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>:
161</p> 168</p>
162 169
163<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
164USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
165</pre> 172</pre>
166 173
167</body> 174</body>
168</subsection> 175</subsection>
169<subsection> 176<subsection>
209update) your changes will be lost! 216update) your changes will be lost!
210</p> 217</p>
211 218
212<p> 219<p>
213As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE-setting
214during the installation of mozilla. 221during the installation of seamonkey.
215</p> 222</p>
216 223
217<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
218# <i>USE="-java" emerge mozilla</i> 225# <i>USE="-java" emerge seamonkey</i>
219</pre>
220
221</body>
222</subsection>
223<subsection>
224<title>Inheriting USE-flags</title>
225<body>
226
227<p>
228Some packages don't only listen to USE-flags, but also provide USE-flags. When
229you install such a package, the USE-flag they provide is added to your USE
230setting. To view the list of packages that provide a USE-flag, check
231<path>/etc/make.profile/use.defaults</path>:
232</p>
233
234<pre caption="A snippet from /etc/make.profile/use.defaults">
235gnome gnome-base/gnome
236gtk x11-libs/gtk+
237qt x11-libs/qt
238kde kde-base/kdebase
239motif x11-libs/openmotif
240</pre> 226</pre>
241 227
242</body> 228</body>
243</subsection> 229</subsection>
244<subsection> 230<subsection>
245<title>Precedence</title> 231<title>Precedence</title>
246<body> 232<body>
247 233
248<p> 234<p>
249Of 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
250USE 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
251<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
252by priority (first has lowest priority): 239by priority (first has lowest priority):
253</p> 240</p>
254 241
255<ol> 242<ol>
256 <li> 243 <li>
257 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
258 </li> 245 your profile
259 <li>
260 Inherited USE setting if a package from
261 <path>/etc/make.profile/use.defaults</path> is installed
262 </li> 246 </li>
263 <li> 247 <li>
264 User-defined USE setting in <path>/etc/make.conf</path> 248 User-defined USE setting in <path>/etc/make.conf</path>
265 </li> 249 </li>
266 <li> 250 <li>
270 User-defined USE setting as environment variable 254 User-defined USE setting as environment variable
271 </li> 255 </li>
272</ol> 256</ol>
273 257
274<p> 258<p>
275To 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
276This 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>
277the content used by Portage. 261variable) with the content used by Portage.
278</p> 262</p>
279 263
280<pre caption="Running emerge info"> 264<pre caption="Running emerge --info">
281# <i>emerge info</i> 265# <i>emerge --info</i>
282</pre> 266</pre>
283 267
284</body> 268</body>
285</subsection> 269</subsection>
286<subsection> 270<subsection>
301were 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
302flags. 286flags.
303</p> 287</p>
304 288
305<warn> 289<warn>
306Running <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
307with 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
308it 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
309<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.
310</warn> 294</warn>
311 295
312<pre caption="Removing obsoleted packages"> 296<pre caption="Removing obsoleted packages">
313# <i>emerge -p depclean</i> 297# <i>emerge -p --depclean</i>
314</pre> 298</pre>
315 299
316<p> 300<p>
317When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 301When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
318applications that are dynamically linked against shared objects provided by 302applications that are dynamically linked against shared objects provided by
336<subsection> 320<subsection>
337<title>Viewing available USE-flags</title> 321<title>Viewing available USE-flags</title>
338<body> 322<body>
339 323
340<p> 324<p>
341Let 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
342find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c> 326find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
343options: 327options:
344</p> 328</p>
345 329
346<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE-flags">
347# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
348These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
349 333
350Calculating dependencies ...done! 334Calculating dependencies ...done!
351[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
352+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
353-moznocompose -moznoxft 337-moznoroaming -postgres -xinerama -xprint" 0 kB
354</pre> 338</pre>
355 339
356<p> 340<p>
357<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
358dedicated to package information called <c>etcat</c> which resides in the 342dedicated to package information called <c>equery</c> which resides in the
359<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 343<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
360</p> 344</p>
361 345
362<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
363# <i>emerge gentoolkit</i> 347# <i>emerge gentoolkit</i>
364</pre> 348</pre>
365 349
366<p> 350<p>
367Now 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
368certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
369</p> 353</p>
370 354
371<pre caption="Using etcat to view used USE-flags"> 355<pre caption="Using equery to view used USE-flags">
372# <i>etcat uses gnumeric</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ]
373[ Colour Code : <i>set</i> <comment>unset</comment> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
374[ Legend : (U) Col 1 - Current USE flags ] 359[ Legend : Left column (U) - USE flags from make.conf ]
375[ : (I) Col 2 - Installed With USE flags ] 360[ : Right column (I) - USE flags packages was installed with ]
376
377 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 ]
378 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 362 U I
379 - - <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
380 + + <i>python</i> : Adds support/bindings for the Python language 367+ + <comment>python</comment> : Adds support/bindings for the Python language
381 + + <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
382</pre> 370</pre>
383 371
384</body> 372</body>
385</subsection> 373</subsection>
386</section> 374</section>

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