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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 1.13 2004/05/07 07:42:53 swift Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.46 2007/04/14 03:09:30 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>
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: 100</p>
101
92</p> 102<p>
93 103A list of available local USE flags can be found locally in
94<pre caption="A short snippet of available USE-flags"> 104<path>/usr/portage/profiles/use.local.desc</path>.
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> 105</p>
103 106
104</body> 107</body>
105</subsection> 108</subsection>
106</section> 109</section>
107<section> 110<section>
108<title>Using USE-flags</title> 111<title>Using USE flags</title>
109<subsection> 112<subsection>
110<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
111<body> 114<body>
112 115
113<p> 116<p>
114In 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
115you how to declare USE-flags. 118you how to declare USE flags.
116</p>
117
118<p> 119</p>
120
121<p>
119As 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>
120variable. 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
121provide 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
122we 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
123in 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.
124this default setting: 127</p>
128
125</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>
126 136
127<pre caption="/etc/make.profile/make.defaults USE variable"> 137<p>
128USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm gtk 138Let us take a look at this default setting for the 2004.3 profile:
129 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses nls 139</p>
130 oggvorbis opengl pam pdflib png python qt quicktime readline sdl slang 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
131 spell ssl svga tcpd truetype X xml2 xmms xv zlib" 147 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
132</pre> 148</pre>
133 149
134<p> 150<p>
135As 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
136<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
137the <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
138you update Portage! 154you update Portage!
139</p> 155</p>
140 156
141<p> 157<p>
142To change this default setting, you need to add or remove keywords to the 158To change this default setting, you need to add or remove keywords to the
143<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable 159<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable
144in <path>/etc/make.conf</path>. In this variable you add the extra USE-flags you 160in <path>/etc/make.conf</path>. In this variable you add the extra USE flags you
145require, or remove the USE-flags you don't want. This latter is done by 161require, or remove the USE flags you don't want. This latter is done by
146prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
147</p> 163</p>
148 164
149<p> 165<p>
150For 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
151following <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>:
152</p> 168</p>
153 169
154<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
155USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
156</pre> 172</pre>
157 173
158</body> 174</body>
159</subsection>
160<subsection> 175</subsection>
176<subsection>
177<title>Declaring USE flags for individual packages</title>
178<body>
179
180<p>
181Sometimes you want to declare a certain USE flag for one (or a couple) of
182applications but not system-wide. To accomplish this, you will need to create
183the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
184<path>/etc/portage/package.use</path>.
185</p>
186
187<p>
188For instance, if you don't want <c>berkdb</c> support globally but you do want
189it for <c>mysql</c>, you would add:
190</p>
191
192<pre caption="/etc/portage/package.use example">
193dev-db/mysql berkdb
194</pre>
195
196<p>
197You can of course also explicitly <e>disable</e> USE flags for a certain
198application. For instance, if you don't want <c>java</c> support in PHP:
199</p>
200
201<pre caption="/etc/portage/package.use 2nd example">
202dev-php/php -java
203</pre>
204
205</body>
206</subsection>
207<subsection>
161<title>Declare temporary USE-flags</title> 208<title>Declare temporary USE flags</title>
162<body> 209<body>
163 210
164<p> 211<p>
165Sometimes you want to set a certain USE-setting only once. Instead of editing 212Sometimes you want to set a certain USE setting only once. Instead of editing
166<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 213<path>/etc/make.conf</path> twice (to do and undo the USE changes) you can just
167declare the USE-variable as environment variable. 214declare the USE variable as environment variable. Remember that, when you
168</p> 215re-emerge or update this application (either explicitly or as part of a system
169 216update) your changes will be lost!
170<p> 217</p>
218
219<p>
171As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE setting
172during the installation of mozilla. 221during the installation of seamonkey.
173</p> 222</p>
174
175<note>
176The <c>emerge</c> command will be discussed more thoroughly in <uri
177link="?part=2&amp;chap=2">Portage and Software</uri>.
178</note>
179 223
180<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
181# <i>USE="-java" emerge mozilla</i> 225# <i>USE="-java" emerge seamonkey</i>
182</pre> 226</pre>
183 227
184</body> 228</body>
185</subsection>
186<subsection> 229</subsection>
187<title>Inheriting USE-flags</title>
188<body>
189
190<p>
191Some packages don't only listen to USE-flags, but also provide USE-flags. When
192you install such a package, the USE-flag they provide is added to your USE
193setting. To view the list of packages that provide a USE-flag, check
194<path>/etc/make.profile/use.defaults</path>:
195</p>
196
197<pre caption="A snippet from /etc/make.profile/use.defaults">
198gnome gnome-base/gnome
199gtk x11-libs/gtk+
200qt x11-libs/qt
201kde kde-base/kdebase
202motif x11-libs/openmotif
203</pre>
204
205</body>
206</subsection> 230<subsection>
207<subsection>
208<title>Precendence</title> 231<title>Precedence</title>
209<body> 232<body>
210 233
211<p> 234<p>
212Of course there is a certain precendence on what setting has priority over the 235Of course there is a certain precedence on what setting has priority over the
213USE 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
214<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
215by priority (first has lowest priority): 239by priority (first has lowest priority):
216</p> 240</p>
217 241
218<ol> 242<ol>
219 <li> 243 <li>
220 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
221 </li> 245 your profile
222 <li>
223 Inherited USE setting if a package from
224 <path>/etc/make.profile/use.defaults</path> is installed
225 </li> 246 </li>
226 <li> 247 <li>
227 User-defined USE setting in <path>/etc/make.conf</path> 248 User-defined USE setting in <path>/etc/make.conf</path>
228 </li> 249 </li>
229 <li> 250 <li>
251 User-defined USE setting in <path>/etc/portage/package.use</path>
252 </li>
253 <li>
230 User-defined USE setting as environment variable 254 User-defined USE setting as environment variable
231 </li> 255 </li>
232</ol> 256</ol>
233 257
234<p> 258<p>
235To 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
236This 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>
237the content used by Portage. 261variable) with the content used by Portage.
238</p> 262</p>
239 263
240<pre caption="Running emerge info"> 264<pre caption="Running emerge --info">
241# <i>emerge info</i> 265# <i>emerge --info</i>
242</pre> 266</pre>
243 267
244</body> 268</body>
245</subsection> 269</subsection>
246<subsection> 270<subsection>
247<title>Adapting your Entire System to New USE Flags</title> 271<title>Adapting your Entire System to New USE Flags</title>
248<body> 272<body>
249 273
250<p> 274<p>
251If 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
252use 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:
253Note however that these steps will take a long time to finish and that work is
254on the way to adjust Portage to handle this behaviour quicker and automatically.
255</p>
256
257<p>
258First of all, rebuild your entire system using the new USE flags:
259</p> 277</p>
260 278
261<pre caption="Rebuilding your entire system"> 279<pre caption="Rebuilding your entire system">
262# <i>emerge --emptytree world</i> 280# <i>emerge --update --deep --newuse world</i>
263</pre> 281</pre>
264 282
265<p> 283<p>
266Next, run Portage' depclean to remove the conditional dependencies that 284Next, run Portage's depclean to remove the conditional dependencies that
267were 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
268flags. 286flags.
269</p> 287</p>
270 288
271<warn> 289<warn>
272Running <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
273with 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
274it 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
275<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.
276</warn> 294</warn>
277 295
278<pre caption="Removing obsoleted packages"> 296<pre caption="Removing obsoleted packages">
279# <i>emerge -p depclean</i> 297# <i>emerge -p --depclean</i>
280</pre> 298</pre>
281 299
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.
282<p> 305</p>
306
307<pre caption="Running revdep-rebuild">
308# <i>revdep-rebuild</i>
309</pre>
310
311<p>
283When 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.
284</p> 313</p>
285 314
286</body> 315</body>
287</subsection> 316</subsection>
288</section> 317</section>
289<section> 318<section>
290<title>Package specific USE-flags</title> 319<title>Package specific USE flags</title>
291<subsection> 320<subsection>
292<title>Viewing available USE-flags</title> 321<title>Viewing available USE flags</title>
293<body> 322<body>
294 323
295<p>
296In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
297we will explain how to manage your installed software and how to work with
298<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
299you how to view what USE-flags a package uses.
300</p> 324<p>
301
302<p>
303Let 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
304find 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>
305anything) and <c>--verbose</c> (give more output) options: 327options:
306</p> 328</p>
307 329
308<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE flags">
309# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
310These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
311 333
312Calculating dependencies ...done! 334Calculating dependencies ...done!
313[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
314+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
315-moznocompose -moznoxft 337-moznoroaming -postgres -xinerama -xprint" 0 kB
316</pre> 338</pre>
317 339
318<p> 340<p>
319<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
320dedicated to package information called <c>etcat</c> which resides in the 342dedicated to package information called <c>equery</c> which resides in the
321<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 343<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
322</p> 344</p>
323 345
324<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
325# <i>emerge --usepkg gentoolkit</i> 347# <i>emerge gentoolkit</i>
326</pre> 348</pre>
327 349
328<p> 350<p>
329Now 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
330certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
331</p> 353</p>
332 354
333<pre caption="Using etcat to view used USE-flags"> 355<pre caption="Using equery to view used USE flags">
334# <i>etcat uses gnumeric</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ]
335[ Colour Code : <i>set</i> <comment>unset</comment> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
336[ Legend : (U) Col 1 - Current USE flags ] 359[ Legend : Left column (U) - USE flags from make.conf ]
337[ : (I) Col 2 - Installed With USE flags ] 360[ : Right column (I) - USE flags packages was installed with ]
338
339 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 ]
340 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 362 U I
341 - - <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
342 + + <i>python</i> : Adds support/bindings for the Python language 367+ + <comment>python</comment> : Adds support/bindings for the Python language
343 + + <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
344</pre> 370</pre>
345 371
346</body> 372</body>
347</subsection> 373</subsection>
348</section> 374</section>

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