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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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7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.26 2004/12/28 20:01:06 cam 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 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>1.23</version> 16<version>1.36</version>
12<date>2004-12-28</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>
18<body> 23<body>
19 24
20<p> 25<p>
21When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
22system 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
27<p> 32<p>
28This 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
29what 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
30would 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
31packages? 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
32with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
33</p> 38</p>
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>
44<subsection> 48</subsection>
49<subsection>
45<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
46<body> 51<body>
47 52
48<p> 53<p>
49Enter 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
50dependency-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,
51Portage 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
52this also alters the dependency information for a package. 57this also alters the dependency information for a package.
53</p> 58</p>
54 59
55<p> 60<p>
68</p> 73</p>
69 74
70</body> 75</body>
71</subsection> 76</subsection>
72<subsection> 77<subsection>
73<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
74<body> 79<body>
75 80
76<p> 81<p>
77There 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.
78</p> 83</p>
79 84
80<ul> 85<ul>
81 <li> 86 <li>
82 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
83 what most people see as USE-flags. 88 what most people see as USE flags.
84 </li>
85 <li> 89 </li>
90 <li>
86 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
87 decisions. 92 decisions.
88 </li> 93 </li>
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>
107
108<p> 100</p>
101
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>
112 106
113</body> 107</body>
114</subsection> 108</subsection>
115</section> 109</section>
116<section> 110<section>
117<title>Using USE-flags</title> 111<title>Using USE flags</title>
118<subsection> 112<subsection>
119<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
120<body> 114<body>
121 115
122<p> 116<p>
123In 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
124you how to declare USE-flags. 118you how to declare USE flags.
125</p>
126
127<p> 119</p>
120
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>make.defaults</path> files part of your profile. Let us take a 126in the <path>make.defaults</path> files part of your profile.
133look at this 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="/usr/portage/profiles/default-linux/x86/2004.3/make.defaults USE variable"> 137<p>
137<comment>(This is an example and might have changed since it was taken)</comment> 138Let us take a look at this default setting for the 2004.3 profile:
139</p>
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>
138USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77 144USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77
139 foomaticdb gdbm gif gpm gtk gtk2 imlib jpeg kde gnome libg++ libwww mad 145 foomaticdb gdbm gif gpm gtk imlib jpeg kde gnome libg++ libwww mad
140 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt 146 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt
141 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib" 147 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
142</pre> 148</pre>
143 149
144<p> 150<p>
149</p> 155</p>
150 156
151<p> 157<p>
152To 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
153<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
154in <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
155require, 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
156prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
157</p> 163</p>
158 164
159<p> 165<p>
160For 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
161following <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>:
162</p> 168</p>
163 169
164<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
165USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
166</pre> 172</pre>
167 173
168</body> 174</body>
169</subsection> 175</subsection>
170<subsection> 176<subsection>
197</pre> 203</pre>
198 204
199</body> 205</body>
200</subsection> 206</subsection>
201<subsection> 207<subsection>
202<title>Declare temporary USE-flags</title> 208<title>Declare temporary USE flags</title>
203<body> 209<body>
204 210
205<p> 211<p>
206Sometimes 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
207<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
208declare the USE-variable as environment variable. Remember that, when you 214declare the USE variable as environment variable. Remember that, when you
209re-emerge or update this application (either explicitly or as part of a system 215re-emerge or update this application (either explicitly or as part of a system
210update) your changes will be lost! 216update) your changes will be lost!
211</p> 217</p>
212 218
213<p> 219<p>
214As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE setting
215during the installation of mozilla. 221during the installation of seamonkey.
216</p> 222</p>
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 the <path>make.defaults</path> files part of 244 Default USE setting declared in the <path>make.defaults</path> files part of
259 your profile 245 your profile
260 </li> 246 </li>
261 <li> 247 <li>
262 Inherited USE setting if a package from
263 <path>/etc/make.profile/use.defaults</path> is installed
264 </li>
265 <li>
266 User-defined USE setting in <path>/etc/make.conf</path> 248 User-defined USE setting in <path>/etc/make.conf</path>
267 </li> 249 </li>
268 <li> 250 <li>
269 User-defined USE setting in <path>/etc/portage/package.use</path> 251 User-defined USE setting in <path>/etc/portage/package.use</path>
270 </li> 252 </li>
272 User-defined USE setting as environment variable 254 User-defined USE setting as environment variable
273 </li> 255 </li>
274</ol> 256</ol>
275 257
276<p> 258<p>
277To 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
278This 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>
279the content used by Portage. 261variable) with the content used by Portage.
280</p> 262</p>
281 263
282<pre caption="Running emerge info"> 264<pre caption="Running emerge --info">
283# <i>emerge info</i> 265# <i>emerge --info</i>
284</pre> 266</pre>
285 267
286</body> 268</body>
287</subsection> 269</subsection>
288<subsection> 270<subsection>
303were 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
304flags. 286flags.
305</p> 287</p>
306 288
307<warn> 289<warn>
308Running <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
309with 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
310it 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
311<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.
312</warn> 294</warn>
313 295
314<pre caption="Removing obsoleted packages"> 296<pre caption="Removing obsoleted packages">
315# <i>emerge -p depclean</i> 297# <i>emerge -p --depclean</i>
316</pre> 298</pre>
317 299
318<p> 300<p>
319When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 301When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
320applications that are dynamically linked against shared objects provided by 302applications that are dynamically linked against shared objects provided by
332 314
333</body> 315</body>
334</subsection> 316</subsection>
335</section> 317</section>
336<section> 318<section>
337<title>Package specific USE-flags</title> 319<title>Package specific USE flags</title>
338<subsection> 320<subsection>
339<title>Viewing available USE-flags</title> 321<title>Viewing available USE flags</title>
340<body> 322<body>
341 323
342<p> 324<p>
343Let 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
344find 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>
345options: 327options:
346</p> 328</p>
347 329
348<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE flags">
349# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
350These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
351 333
352Calculating dependencies ...done! 334Calculating dependencies ...done!
353[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
354+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
355-moznocompose -moznoxft 337-moznoroaming -postgres -xinerama -xprint" 0 kB
356</pre> 338</pre>
357 339
358<p> 340<p>
359<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
360dedicated to package information called <c>etcat</c> which resides in the 342dedicated to package information called <c>equery</c> which resides in the
361<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 343<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
362</p> 344</p>
363 345
364<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
365# <i>emerge gentoolkit</i> 347# <i>emerge gentoolkit</i>
366</pre> 348</pre>
367 349
368<p> 350<p>
369Now 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
370certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
371</p> 353</p>
372 354
373<pre caption="Using etcat to view used USE-flags"> 355<pre caption="Using equery to view used USE flags">
374# <i>etcat uses gnumeric</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ]
375[ Colour Code : <i>set</i> <comment>unset</comment> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
376[ Legend : (U) Col 1 - Current USE flags ] 359[ Legend : Left column (U) - USE flags from make.conf ]
377[ : (I) Col 2 - Installed With USE flags ] 360[ : Right column (I) - USE flags packages was installed with ]
378
379 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 ]
380 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 362 U I
381 - - <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
382 + + <i>python</i> : Adds support/bindings for the Python language 367+ + <comment>python</comment> : Adds support/bindings for the Python language
383 + + <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
384</pre> 370</pre>
385 371
386</body> 372</body>
387</subsection> 373</subsection>
388</section> 374</section>

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