/[gentoo]/xml/htdocs/doc/en/handbook/hb-working-use.xml
Gentoo

Diff of /xml/htdocs/doc/en/handbook/hb-working-use.xml

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

Revision 1.21 Revision 1.46
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 1.21 2004/10/21 10:31:20 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:
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 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>
147To 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
148<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
149in <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
150require, 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
151prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
152</p> 163</p>
153 164
154<p> 165<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>
192</pre> 203</pre>
193 204
194</body> 205</body>
195</subsection> 206</subsection>
196<subsection> 207<subsection>
197<title>Declare temporary USE-flags</title> 208<title>Declare temporary USE flags</title>
198<body> 209<body>
199 210
200<p> 211<p>
201Sometimes 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
202<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
203declare the USE-variable as environment variable. Remember that, when you 214declare the USE variable as environment variable. Remember that, when you
204re-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
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>
212 223
213<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
214# <i>USE="-java" emerge mozilla</i> 225# <i>USE="-java" emerge seamonkey</i>
215</pre>
216
217</body>
218</subsection>
219<subsection>
220<title>Inheriting USE-flags</title>
221<body>
222
223<p>
224Some packages don't only listen to USE-flags, but also provide USE-flags. When
225you install such a package, the USE-flag they provide is added to your USE
226setting. To view the list of packages that provide a USE-flag, check
227<path>/etc/make.profile/use.defaults</path>:
228</p>
229
230<pre caption="A snippet from /etc/make.profile/use.defaults">
231gnome gnome-base/gnome
232gtk x11-libs/gtk+
233qt x11-libs/qt
234kde kde-base/kdebase
235motif x11-libs/openmotif
236</pre> 226</pre>
237 227
238</body> 228</body>
239</subsection> 229</subsection>
240<subsection> 230<subsection>
241<title>Precedence</title> 231<title>Precedence</title>
242<body> 232<body>
243 233
244<p> 234<p>
245Of 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
246USE 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
247<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
248by priority (first has lowest priority): 239by priority (first has lowest priority):
249</p> 240</p>
250 241
251<ol> 242<ol>
252 <li> 243 <li>
253 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
254 </li> 245 your profile
255 <li>
256 Inherited USE setting if a package from
257 <path>/etc/make.profile/use.defaults</path> is installed
258 </li> 246 </li>
259 <li> 247 <li>
260 User-defined USE setting in <path>/etc/make.conf</path> 248 User-defined USE setting in <path>/etc/make.conf</path>
261 </li> 249 </li>
262 <li> 250 <li>
266 User-defined USE setting as environment variable 254 User-defined USE setting as environment variable
267 </li> 255 </li>
268</ol> 256</ol>
269 257
270<p> 258<p>
271To 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
272This 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>
273the content used by Portage. 261variable) with the content used by Portage.
274</p> 262</p>
275 263
276<pre caption="Running emerge info"> 264<pre caption="Running emerge --info">
277# <i>emerge info</i> 265# <i>emerge --info</i>
278</pre> 266</pre>
279 267
280</body> 268</body>
281</subsection> 269</subsection>
282<subsection> 270<subsection>
297were 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
298flags. 286flags.
299</p> 287</p>
300 288
301<warn> 289<warn>
302Running <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
303with 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
304it 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
305<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.
306</warn> 294</warn>
307 295
308<pre caption="Removing obsoleted packages"> 296<pre caption="Removing obsoleted packages">
309# <i>emerge -p depclean</i> 297# <i>emerge -p --depclean</i>
310</pre> 298</pre>
311 299
312<p> 300<p>
313When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 301When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
314applications that are dynamically linked against shared objects provided by 302applications that are dynamically linked against shared objects provided by
326 314
327</body> 315</body>
328</subsection> 316</subsection>
329</section> 317</section>
330<section> 318<section>
331<title>Package specific USE-flags</title> 319<title>Package specific USE flags</title>
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>
337Let 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
338find 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>
339options: 327options:
340</p> 328</p>
341 329
342<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE flags">
343# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
344These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
345 333
346Calculating dependencies ...done! 334Calculating dependencies ...done!
347[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
348+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
349-moznocompose -moznoxft 337-moznoroaming -postgres -xinerama -xprint" 0 kB
350</pre> 338</pre>
351 339
352<p> 340<p>
353<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
354dedicated to package information called <c>etcat</c> which resides in the 342dedicated to package information called <c>equery</c> which resides in the
355<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 343<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
356</p> 344</p>
357 345
358<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
359# <i>emerge gentoolkit</i> 347# <i>emerge gentoolkit</i>
360</pre> 348</pre>
361 349
362<p> 350<p>
363Now 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
364certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
365</p> 353</p>
366 354
367<pre caption="Using etcat to view used USE-flags"> 355<pre caption="Using equery to view used USE flags">
368# <i>etcat uses gnumeric</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ]
369[ Colour Code : <i>set</i> <comment>unset</comment> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
370[ Legend : (U) Col 1 - Current USE flags ] 359[ Legend : Left column (U) - USE flags from make.conf ]
371[ : (I) Col 2 - Installed With USE flags ] 360[ : Right column (I) - USE flags packages was installed with ]
372
373 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 ]
374 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 362 U I
375 - - <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
376 + + <i>python</i> : Adds support/bindings for the Python language 367+ + <comment>python</comment> : Adds support/bindings for the Python language
377 + + <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
378</pre> 370</pre>
379 371
380</body> 372</body>
381</subsection> 373</subsection>
382</section> 374</section>

Legend:
Removed from v.1.21  
changed lines
  Added in v.1.46

  ViewVC Help
Powered by ViewVC 1.1.20